STUDIES ON POWDERY MILDEW OF CUCURBITS

DISSERTATION S U B M I T T B S ,

TO THE AL IGARFI MUSLIM UNIVERSIl^i^, ALIGARH

IN PARTIA4-»€GUlLNfeNt*0F ..THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF PHILOSOPHY IN

BOTANY

GIRISH KUMAR SHARMA

DEPARTMENT OF BOTANY ALIGARH MUSLIM UNi\/ERSITY

ALIGARH (INDIA)

1987

DS1324

STUDIES ON POWDERY MILDEW OF CUCURBITS

M. Phil. DISSERTATION

GIRISH KUMAR SHARMA

DEPARTMENT OF BOTANY ALIGARH MUSLIM UNIVERSITY

ALiGARH (INDIA)

1987

Dr. M. WAJID KHAIS M Sc (Ban ) Ph D (A l ig ), F L S F P S I

READER

Principal Investigator CSIR Project—Airpollution-animate

plant pathogen interaction^

ICAR Project —Root-knot nematodes

UCC Project -Cucurbit powdery mildews

Plant Pathologv and Plant Noniato1np\

Laboratories

DEPARTMENT OF BOTANY

Al IC.ARH MUSI IM l ' \ l \ 1 R S n \ ALlGARH-^.i: (»ii2 INDIA

Datetl...)..} ' . ' . .

CERTIFICATE

This is to certify that Mr. Girish Kumar Snarma

has prepared this dissertation as required for M.Phil.

(Botany) degree of the Aligarh Muslim University,Aligarh,

under my supervision and guidance. He is allowed to

submit this dissertation for evaluation in partial fulfil­

ment of the requirements for the degree of Master of

Philosophy in Botany.

( M.Wajid Khan )

Research Supervisor

ACKNOWLEDGEMENTS

I would l i k e to express my g r e a t g r a t i t u d e to

Dr. M.Wajid Khan, P r i n c i p a l I n v e s t i g a t o r of U.G.C., I .C.A.R.

and C .S . I .R . P r o j e c t s and Reader, Department of Botany,

Al igarh Muslim U n i v e r s i t y , A l iga rh , my superv i so r for

sugges t ing the problem, encouragement, a c t i v e guidance and

keen i n t e r e s t i n p lanning my s t u d i e s for Ph.D. and p r epa ra ­

t i o n of M.Phi l , d i s s e r t a t i o n .

A g r a t e f u l acknowledgement i s made to Prof. Khalid

Mahmood, Chairman, Department of Botany, Al igarh Muslim

U n i v e r s i t y , A l iga rh , for p rov id ing the f a c i l i t i e s .

F inanc i a l a s s i s t a n c e by the Un ive r s i t y Grants Commission

(UGC), New De lh i , through Jun io r Research Fellowship sanct ioned

i n the UGC P r o j e c t (No.3-3 /86(SR-I I ) under the superv i s ion

of Dr.M.Wajid Khan i s a l s o g r a t e f u l l y acknowledged.

1 am g r e a t l y thankful to Dr .S .S .Ashraf (R .A . ) , Dr.

Salahuddin ( S . R . F . ) , Dr. Nisar A.Ansar i , Mr. A.A.Khan ( S . R . F . ) ,

Mr. S.R.Haider ( S . R . F . ) , Mr. M.R.Khan, Mr. S.K.Singh,

Mr. Shahid Perwez and Mr.Mohd.Imran Khan, Research Scholars in

Botany for t h e i r kind help and coope ra t ion dur ing the review

of l i t e r a t u r e and p r e p a r a t i o n of the d i s s e r t a t i o n .

I wish to extend my a p p r e c i a t i o n to my f r i ends

Mr.Raj Kumar Sharma, Mr.Mohd.Nafees, Narendra Kumar Sharma,

Rajeev Kumar Tyagi and Mohd.Rashid Siddiqui for t h e i r coopera t ion

and unde r s t and ing . I am indebted to my p a r e n t s and o ther

i i

family members for their encouragements, support and care

throughout my educational growth and preparation of M.Phil.

dissertation.

Finally, I beg to express my gratitude, thanks, appre­

ciation and indebtness to the "ALMIGHTY GOD" for providing

and guiding all the channels to work in cohesion and coordi­

nation to make this study possible.

lii

LIST OF CONTENTS

Page

INTRODUCTION

LITERATURE REVIEW

Powdery Mildew of Cucurbits

a. Geographical distribution of the disease .

b. Economic significance and loss estimates «

c. Affected crops

do Symptoms

e. Causal organisms

Identity of the Causal Organisms

a. Values of different structures of conidial stage (anamorph) in the taxonomy of powdery mildews of cucurbits

b. Identification of the pathogen in absence of teleomorph

Host Flange and Host Specificity

Host Races

Varietal Resistance

Environmental Relationships

Perithecial Rjrmation in Powdery Mildews ol Cucurbits

Survival and Perpetuation

MATERIALS AND METHODS

1. Survey and Collections

2, Identity of Causal Organisms

a. Fibrosin bodies test

b. Germination test

c. Host differential test

1

9

11

12

14

16

18

19

27

50

53

57

65

68

71

80

87

90

90

93

93

9A

94

iv

Page

3. Culturing and Maintenance of the Pathogen

4. Host Range Studies

5o Screening of Cultivars

60 Consistency in Conidial Characters

601 Effect of culturing

a. Continuous culturing with same host

b, Culturing on different cucurbits

6.2 Effect of certain ecological factors

603 Effect of nutritional status

7. Effect of nutritional status and Age on the consistency of the differential Host

8. Race Differentiation

1, Cross inoculation

2, Response of host differentials

95

96

96

98

98

98

99

99

100

100

101

102

103

LITERATURE CITES 105

LIST OF TABLES

Page

1. Occurrence of powdery mildew on cucurbits in

different countries of the world ... 13

2. Records of Leveillula taurica on cucurbits in

different countries of the world. ... 21

3. Records of Eryslphe cichoracearum as the

causal organisift of the pOM*dery mildevj of

cucurbits in different countries of the world. ... 22

4. Records of Sphaerotheca fuliginea as the

causal organism of the powdery mildew of

cucurbits in different countries of the world ... 23

5. Records of both Erysiphe cichoracearum and

Sphaerotheca fuliginea as causal organisms

of the powdery mildew of cucurbits in

different countries of the world ... 24

6. Records of Oidium species on cucurbitaceae

from different countries of world ... 25

7. Identity situations of powdery mildew in

different countries of the world ... 28

8. Identity situation of powdery mildew in India ... 47

9. Records of perithecia of Erysiphe cichoracearum on cucurbits ... 74

10. Records of perithecia of Sphaerotheca fuliginea

on cucurbits ... 77

11. Records of perithecia of Erysiphe cichoracearum

on cucurbits from India ... 82

12. Records of perithecia of Sphaerotheca fuliginea

on cucurbits from India ... 83

vi

INTRODUCTION

Powdery mildews are one of the most conspicuous

parasitic fungi on plants of economic importance. Several

crop plants including a number of cucurbits suffer greatly

due to powdery mildews. Cucurbits are widely cultivated

throughout India to be used as vegetables, ripe or raw fruits,

ingradients of salad, in confectionary and for oil extraction.

Powdery mildew of cucurbits is a serious disease and

causes considerable loss to the crops of a number of cucurbi-

taceous crops grown in India. Three powdery mildews species,

Sphaerotheca fullginea (Schlecht. ex Fr.) Poll., Erysiphe

cichoracearum DC, ex Merat and Leveillula taurica (Lev.)

Arnaud, are well established causal organisms of the disease

on cucurbits on world-wide basis. Of these S, fuliginea and

E. cichoracearum are more commonly encountered on cucurbits

in different parts of the world; . fuliginea is apparently

more prevalent (Khan, 1983). All the three species are reported

to exist on cucurbits in India as well (Khan,1983). S.fuliginea

and E. cichoracearum are known to occur on cucurbits in certain

States of India like Uttar Pradesh, Madhya Pradesh, Bihar and

Rajasthan (Khan et al., 1971; Khan, 1976,1977; Dave £t al.,1971;

Khosla et aJ., 1974; Siradhana and Chaudhari, 1972). In some

States like Kashmir and Punjab only . fuliginea is reported

to cause the disease on cucurbits (Khan et al., 1974;

Jhooty, 1967). L. taurica has been reported to infect cucur­

bits' in Rajasthan and Karnataka (Mahrshi and Siradhana, 1980;

Ullasa and Amin, 1981).

Anaraorphs of S. fuliglnea and E. clchoracearum have

great similarities and teleomorphs are not common. Symptoms

of the disease caused by them are identical. Therefore,

there has been a great deal of confusion throughout the world

with regard to the identity of the causal organism of the

disease. In recent past, some efforts have been made in

different countries of the world including India to establish

the correct identity of the species involved in the disease.

Jhooty (1967) identified the cause of powdery mildew of

cucurbits in Punjab on the basis of anamorph as S^, fuliginea.

Khan and Khan (1970) while studying perithecial production in

cucurbit powdery mildews on cucumber and bottle-gourd culti-

vars in the glasshouse identified the causal organism in

Uttar Pradesh as S, fuliginea. However, in a later study.

Khan et al_. (1971) observed that S. fuliginea was responsible

mainly for the disease in nature and E. clchoracearum was

confined to Coccinia cordifolla, a wild cucurbit. Siradhana

and Chaudhari (1972) recorded occurrence of both the species

on cucurbits in Rajasthan.

Dave al., (1971) recorded existence of both species

on cucurbits in Madhya Pradesh and found teleomorphs of

^. fuliginea on L. sicerarla (= L. leucantha) and Luffa

cylindrica and those of E. clchoracearum on T. dioica. From

a survey conducted by Khan et al. (1974) in Kashmir, it

emerged that Ss fuliginea is most prevalent species in the

State and attacks a number of cucurbits like Cucurblta maxima.

C. pepo, Cucumis sativus, Citrullus vulgaris and Luffa

acutangula. They observed perithecia of S, fuliginea on

L, leucantha at Wadura and on C, maxima in Dal Lake area.

Khan (1976) after a survey in Bihar found that both species

were present on cucurbits in the State. They were observed

both in conidial as well as in perithecial stages. Perithecia

of E. cichoracearum were found on . cordifolia at Sheikhpura

in Patna and of S.fuliginea on L. leucantha at Sheikhpura

(Patna) and Patna city area. He further noticed that most

severely affected cucurbit was L. leucantha followed by

Cucurbita moschata, Cucumis melo, C. melo var. utilissimus

and C, cordifolia. Sohi and Nayar (1969) reported the

occurrence of . fuliginea in Himachal Pradesh and observed

its peritheceal stage on C. moschata.

In recent past, in the States where pre-dominance of

^. fuliginea has now been recognised, E. cichoracearum was

considered as casual organism of the disease since long,

without proper verification. In several States of India,

this verification is yet to be done. This situation demands

a clear understanding regarding the number of powdery mildew

species on cucurbits, their distribution pattern in different

States and their relative dominance in the area. Identifica­

tion of the pathogen responsible for cucurbit powdery mildew

disease in different agro-climatic zones of the country is a

matter of fundamental importance and of economic consequence.

This information is essential and useful in breeding programmes

for resistant cultivars and for adopting other control measures

for the management of the disease.

When perithecia are present, identification of the

powdery mildew species infecting cucurbits becomes very easy

but as they are rarely produced by the species on cucurbits

and develop usually in their conidial stage, a great deal

of confusion surrounds their identity. L. taurica is easily

distinguishable from the other two species even if only

conidial stage is present. But conidial stages of S. fuliginea

and E. cichoracearum have great similarities. However, some

of the features of conidia have been utilised to differentiate

E. cichoracearum from S. fuliginea. Such prominent features

are presence or absence of well-developed fibrosin bodies also

known as 'Corpusules de Zoff, mode of germination of conidia,

morphology of germ tube and development of appressoria. The

conidia of _S-. fuliginea ordinarily possess a number of well-

developed fibrosin bodies. Fibrosin bodies are lacking or

not well-developed in the conidia of E. cichoracearum. This

feature is claimed as more or less consistent but there are

records of conidia of S. fuliginea without fibrosin bodies

(Yarwood, 1978). Conidia of S. fuliginea when germinate, a

number of them form forked germ tubes and do not produce

appressoria. In contrast, conidia of E. cichoracearum form

simple germ tubes with thick walled club-shaped appressoria.

These conidial characters have been recognised valuable in

distinguishing the anamorphs of E. cichoracearum from those

of S. fuliginea. Shape and size of conidia and rate of

germination have also been advocated for use in identification

of their species (Sitterly, 1978; Khan, 1983).

Some of the conidial characters have been reliably used

in establishing the identity of powd&ry mildews of cucurbits

in several countries in the absence of perithecia. Fibrosin

bodies and germination characters are apparently stable

characters for differentiating these two species but some

doubts have been expressed about their reliability. Whether

these features of conidia are consitent characters, whether they

are influenced by ecological factors, host or cultivar involved

or nutritional status of the host are intriguing questions

which need to be answered. For answering such questions,

comprehensive studies are needed which can examine the consis­

tency and reliability of these features before they can be used

as universal characters.

Host specificity and host range are also used as an

aid for identification of plant pathogens. As . fuliginea

and E, cichoracearum have wide and overlapping host ranges.

It seemed difficult that host specificity may be of some help

for establishing their identity. Khan (1978), however,

proposed C. cordifolia and L, leucantha as prospective host

differentials for distinguishing between these two species.

It was observed that C, cordifolia was invariably attacked by

E. cichoracearum which was unable to infect L. leucantha. On

the other hand, S, fuliginea invariably infected L. leucantha

and not Cs cordifolia. He proposed the two cucurbits can be

reliably used for differentiating these two species. However,

he suggested to observe their consistency by testing different

cultivars of L» leucantha and C, cordifolia against the races

of E. cichoracearum and S. fuliginea.

A number of varieties (cultivars) of different cucurbits

are grovm in different parts of the world including India. New

varieties are regularly bred and introduced for commercial

cultivations. It is expected that their responses to powdery

mildews are tested under varied conditions before their intro­

duction. The presence of races in powdery mildews of cucurbits

poses a difficult problem in breeding cucurbit varieties

resistant to the disease. A slight slip on the part of the

breeder regarding the race flora of a region for which the

variety is being evolved may results in complete failure of

the variety. Some high yielding varieties of cucurbits have

been evolved and found resistant to one or more of the powdery

mildews in a particular locality. The same varieties when

grown under similar climatic conditions in a different locality

are found susceptible to the same powdery mildews. Apparently,

this happens because the races in this new locality are missed

while the variety is tested against known races of the powdery

mildews. Thus, a large race flora complicates the problem of

developing varieties resistant to one or more of the powdery

mildews. The breeding and introduction of new varieties of

cucurbits with different attributes is a regular process and

therefore, it is imperative to test response of different

varieties of cucurbits, to different species of powdery mildews

and their races. The multiplicity of the pathogens involved

in this disease has special significance in this respect. It

is advisable that all the commercially grown cultivars

(varieties) of different species of cucurbits are screened

for their resistance against all the three species or at

least against S. fuliginea and E. cichoracearum.

The three species causing the disease may have different

ecological requirements. There are such indications for

E. cichoracearum and S. fuliginea (Nagy, 1970). L. taurica

is considered as a pathogen of the Mediterranean belt of the

world, perhaps due to its specific ecological preferences.

Effects of different environmental factors specially tempera-

ture and relative humidity on spore germination and disease

development have not been fully studied for all the three

pathogens in relation to cucurbits. A persual of literature

shown their varied distributions in different areas of the

world. The variations may be due to differences in climatic

conditions of various countries.

There are some records of races of powdery mildews

causing disease on cucurbits in different parts of the world.

Alcorn (1959) reported four'pathogenically distinct races of

_S. fuliginea on cucurbits in Queensland. Abiko (1978) found

five distinct specialized forms of . fuliginea on cucurbi-

taceous and non-cucurbitaceous plants. In India, powdery

mildew on cucurbits appears every year. It is of common

observance that some of the cucurbits in a area of region

are heavily infected while some remain free from the disease.

8

which are attacked in another area or region. This diffe­

rential appearance of the disease indicates the possibility

of existence of races with in species causing the disease.

Kaur and Jhooty (1985) in Punjab have noted the occurrence

of three different pathological forms on the basis of diffe­

rential reaction. However, in the rest part of India no

attempts has been made to detect the existence of races in

powdery mildews of cucurbits especially in S. fuliginea which

is considered as most dominant species in the country.

In the proposed programme of research for Ph.D., it

is planned to study the following espects of the powdery mildew

disease of cucurbits;

1, Survey of different cucurbits to assess the incidence and

intensity of the powdery mildew disease in the cucurbit

growing areas of some States of India,

2, Identification of the causal organism(s) in order to

establish the identity of powdery mildew(s) of cucurbit

in India,

3, Host range studies of S. fuliginea and E. cichoracearum.

4, Screening of cultivars of some commonly grown cucurbits

against . fuliginea and E. cichoracearum.

5, Studies on consistency in conidial characters for their

use in identification of . fuliginea and E. cichoracearum,

6, Differentiation of races in S. fuliginea.

LITERATURE REVIEW

The family Cucurbitaceae contains about 90 genera and

750 species, almost equally divided between the new and old

world tropics. According to Chakravarty (1959), out of the

108 species occuring in India, 38 are apparently endemic.

Of these, some are confined to Peninsular India and Ceylon

and others to the Eastern Himalaya and Burma. Rheede (1805)

and Roxburg (1932) reported that Lagenaria vulgaris had been

found to be wild in India. De Candolle (1882) reported that

Citrullus vulgaris was indigenous to tropical Africa, while

Pangalo (1930, 1944, 1955) on the basis of extensive studies on

Asiatic watermelons concluded that C, vulgaris was indigenous

to India. Naudin (1859) pointed out that species of Cucumis

were African in origin except C. anguria and suggested that

it could had been introduced into the America through slave

trade. Hooker (1879) expressed the same view. According to

Meeuse (1958) Cucumis anguria was a cuttigen descended from a

non-bitter variant (mutant) of an African wild species,

described as Cucumis longipes Hook., which normally had bitter

fruits. There are undoubtedly well-developed secondary centres

of origin of Cucumis melo in India, Persia, Southern Russia

and China (Hill, 1979).

According to Naudin (1859) Luffa cylindrica was probably

a native of Southern Asia and perhaps also of Africa, Australia

and Polynesia. Rheede (1805) observed L, cylindrica growing

in sandy places, in woods and other localities in Malabar,

10

while Roxburg (1832) claimed that it was wild in undivided

India subcontinent. Clarke (1879) claimed that Luffa

acutan^ula was indigenous to British India. Bailey (1929)t

while discussing the origin of the domesticated species of

Cucurbita presented convincing evidences that it had Mexican

or Texan origin. Erwin (1931) stated that there was a good

evidence that Cucurbita moschata and Cs pepo were indigenous

to South America. According to Clarke (1879) India is the

original home of Trichosanthes angulna.

A number of species of family Cucurbitaceae and

varieties of the some of the taxonomic species are cultivated

in different parts of the world. Citrullus lanatus Mansf.

or Cs vulgaris Schard., _C. vulgaris var. fistulosus Stewart,

Cucumis melo L, C^, melo var, momordlca Roxb., Cucumis sativus L.

Cucumis anguria L., C, melo var. utilissimus Roxb. Luffa

cylindrica (L.) Roem., Luffa acutangula (L.) Roxb., Lagenaria

leucantha (Duch.) Rusby, Cucurbita pepo (L.), Cucurbita mixta

Pong. Cucurbita maxima Duch., Cucurbita moschata Poiret,

Cucurbita ficifolla Bouche, Sechium edule Swartz, Trichosanthes

anguina L., Trichosanthes dioica Roxb,, Momordica charantia L.,

Momordica dioica Roxb,, Benincasa hispida (Thunb,) Cong, and

Cyclanthera pedata Schrad are cultivated in many different

areas in the world (Chakravarty, 1959; Khan, 1972 and

Sitterly, 1978).

Cucurbits constitute an important group of vegetables

and raw and ripe fruits and are grown almost all over the

world. They serve as a good source of carbohydrates, vitamins

11

and minerals. They are used as dessert and salad ingradients,

and pickles. Some cucurbits are used as babkets, as insulation,

as soil filters and as alternatives of pottery and utensils.

From seeds of certain cucurbits, oil is extracted. From the

hollow dried fruit of bottlegourd, L. leucantha some musical

instruments are made. Ashgourd, B. hispida is primarily used

in confectionary industry. A few species of Citrullus and

of Cucumis are of medicinal importance (Hill, 1979). Specially

in India their significance as food crops is more because bulk

of the population in the country happens to be vegetarian.

Cucumber, melons, pumpkins, squashes and gourds are

hot weather crops and are mostly trailers with the exception

of bushy varieties of squash. They trive best in light loamy

soils and are grown all over India. Pointed gourd (parwal) is

seldom grown in North-west India and the watermelon and

muskmelon in the hills. All of them are propagated from the

seeds. However, pointed gourd can also be propagated by

cuttings.

In the hilly regions, the seed is sown from April to

July while in the plains from January to March. Late rainy

season crop of bitter gourd is also raised during May to July.

Powdery Mildew of Cucurbits

Cucurbits are attacked by large number of plant

pathogens (Whitaker and Davis, 1962). In amongst them the

most serious is the powdery mildew fungus. Powdery mildew

disease of cucurbits is world-wide in distribution and is

12

found wherever cucurbits are grown (Hirata, 1968) (Table 1).

Both indoor and outdoor cultivations of cucurbits suffer

variously due to this disease.

The importance and severity of the disease is more in

glasshouses than in the field because of favourable environ­

mental conditions such as moderate to high temperature, high

soil moisture, reduced air circulation, reduced light intensity

and continuous cropping (Ballantyne, 1975; Sitterly, 1978).

a* Geographical distribution of the disease;

Hirata (1968) analysed the geographical distribution

of powdery mildews in the world including powdery mildew of

cucurbits. He listed its presence in all continents of the

world. In Europe, it was listed to occur in Finland, Sweden,

Norway, U.S.S.R. (European region), Poland, Czeckoslovakia,

Rumania, Bulgaria, Hungary, Denmark, Holland (The Netherlands),

United Kingdom, Germany, Switzerland, Greece, Yugoslavia,

Italy, France, Portugal and Malta. In Pacific, it was reported

in Japan, Formosa (Taiwan), Hawaiian Is., Philippines,

Indonesia, New Guinea, Fiji, Tonga, New Caledonia, Norfold,

Australia and Newzealand. In Asia continent, it was listed

in Korea, China, Combodia, Thailand, Burma, Nepal, Ceylon,

U.S.S.R. (Asian Region), Afghanistan, India, Pakistan, Iran,

Iraq, Turkey, Lebanon, Palestine, Jordan, Cyprus, Malaysia and

Singapore.

In North America, it was reported to occur in Canada,

U.S.A., Mexico, Gautemala, El-Salvador, Hondura, Nicaragua,

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N to •H c • CO C bO CD

< t-H

CO

ft CO CO E H

CO 36

C 2 -H •H - O ft • -H ft CO IJL, •H - H rH CO •

CU to C o • d a

•H

x: c to M M O

(H CD U, +J CO

3

H

bO cu 1 3 C rH T O to S H O g

CO - H c o

CD • H c cu B

< :

I

cu

CO

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C CO e rH to to CO cu

B U 0)

i x: 3 O

CO u,

• H <U

CD CO to

X >

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• H > CO rH

CO - d • CO

j a CO

6

CO O

o

to

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N

U <H <

CO bO

» CO • T )

CO CD

• CO N CO CU b O

CO

c

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3

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to

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rH

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14

Panama, Bermuda, Jamaica and Trinidad; and in South America

in Venezuela, Brazil, Peru, Bolivia, Uraguary and Argentina.

In Africa, the reports were for Ethiopia, Kenya, Senegal,

Sierraleone, Ghana, Uganda, Tanzania, Mozambique,Zambia,

Zimbabwe, South Africa, Madagascar, Mauritius, Sudan, Egypt,

Libya, Tunisia and Morocco (Hirata, 1968) (Table 1). Since

then, some new countries were added to the list of countries

known to have powdery mildew of cucurbits e.g. Austria as

reported by Glaeser (1970) and Saudi Arabia (Abul-Hayja and

Trabulusi, 1981).

b. Economic significance and loss estimates:

Although world-wide occurrence of the disease on a

variety of cucurbits is well established but the estimates of

losses due to the disease are very few. The extent of damage

to different crops in various parts of the world are also

not well demonstrated. Neverthless, there have been few

attempts to assess the intensity of the disease and extent of

damage on certain cucurbit crops. Milbrath (1927) reported

that powdery mildew of cantaloupe in California was highly

destructive in which 35,000 acres of this crop had been

attacked. The disease was reported from most of the States

of U.S.A. in some instances causing appreciable losses in the

greenhouse and field (Miller and Barrett, 1931). In 1950,

greenhouse cucumbers were severely attacked by the powdery

mildew in Alaska (Anon., 1950). Fikry (1936) mentioned that

all the cucurbits that were cultivated in Egypt are attacked by

powdery mildews.

15

Reichart et al_. (1943) recognised powdery mildew as one

of the major diseases affecting vegetable marrows in Palestine.

Allison (1952) considered that disease as one of the most common

and the economically most important vegetable crop in Iraq.

In Mozambique the disease was mentioned as of great economic

importance (De Carvalho, 1948). Blackford (1943) reported

that powdery mildew was one of the most destructive disease

affecting cucumbers in Queensland (Australia). Glaeser (1970)

stated that among the important diseases causing injury to

cultivated plants was powdery mildew of cucumbers in Austria,

In Moldavia (U.S.S.R,), all cultivated cucurbits were observed

to be affected with powdery mildews (Nikiforova,1962). Masurat

and Stephan (1965) reported that disease was of wide-spread

with intensity varying from moderate to severe, affecting

18-50% of the area in the German Democratic Republic (East

Germany). In Britain, Stone (1962) mentioned that the disease

was common on cucurbit crops appearing every year under glass­

house as well as on outdoor cultivations. Jhooty (1971)

considered the disease as one of the most serious diseases of

cucurbits in Northern India. Studies of Khan and his associates

supported this view that the disease was prevalent in the

different states of North India like Kashmir (Khan _et al. ,1974);

Uttar Pradesh (Khan, 1972) and Bihar (Khan, 1977). Siradhana

and Chaudhari (1972) found this disease as important one on

cucurbits in Rajasthan.

Boyd (1928) estimated that the economic losses in the

cantaloupe crops in Georgia (U.S.A.) in 1928 was 12%. In

Astrakhan region of U.S.S.R., Szembel (1930) reported 75%

16

reduction in the yield of cucumbers due to the infection of

powdery mildews, McKeen (195 ) reported 50% reduction in tne

yield of muskmelon in Ontario, Canada. Tafradzhiiski (1959)

reported that powdery mildew of cucumber caused more than

50% loss in the yield in Bulgaria in 1958.

c. Affected crops;

All the cultivated species are infected with powdery

mildew in different parts of the world (Hirata, 1966). However,

records of field infection and host range studies in outdoor

field plots and indoor cultivation units, indicate variance in

the degree of susceptibility of different cultivated cucurbits.

Further, intensity and incidence of the disease on the same

cucurbit varies in different areas (Khan, 1972). Fikry (1936)

reported that powdery mildew attacked all the cultivated species

of Cucurbitaceae in Egypt except the watermelon which was

affected in damp localities. In New South Wales (Australia)

in 1950, it was reported that the disease severity was less

on watermelon, than on rock melons, cucumber, marrows, squashes

and pumpkins (Anon., 1950). Teterevenikova-Babayan and

Simonyan (1956) claimed in their detailed study on powdery

mildews of cucurbits in Armenia (U.S.S.R.) that the disease was

very severe on cucumbers and melons and less on watermelons,

pumpkins and marrows. Stone (1962) found that in Britain among

all the Cucurbitaceae only the genus Luffa was immune to

infection of powdery mildews.

Ballantyne (1975) stated that powdery mildew was very

serious disease of susceptible muskmelon cultivars in many

17

countries. Pumkin, marrows, squashes and cucumbers were less

affected while watermelon was not often affected but sometimes

with an occasional out break. On the other hand, there are

some records indicating that powdery mildew is a comiron disease

on watermelon. Ragimov (1961) and Sokolov (1978) claimed

that the watermelon was commonly infected with powdery mildew

in U.S.S.R, In Hungary, along with cucumber, melons and

marrows, watermelon were attacked with powdery mildew (Ubrizsy,

19A6). In other areas, the disease on watermelon is not common.

McLean (1970) mentioned that watermelon was not considered as

susceptible to powdery mildew in U.S.A., but he recognized

infection on two breeding lines of watermelon which were

generally considered resistant to the disease.

Khan £t al. (1974) in their study of on incidence and

intensity of cucurbit powdery mildew in Kashmir (India) found

that the most severely affected cucurbits were squashes, marrows,

bottle gourd and cucumbers. Watermelon was found rarely

infected, while spongegourd was free from the disease. Khan

(1977) in his study on incidence and intensity of powdery

mildews on fourteen cucurbits in Bihar (India) found that

Legenaria leucantha and Cucurbita moschata were most severely

affected cucurbits. Cucumis melo, £. melo var. utilissimus

and Coccinia cordifolia were less infected. C. melo var.

momordica, Cucumis sativus, Citrullus vulgaris, Trichosanthes

anguina, _T. dioica, Momordica charantia, M. dioica. Luff a

cylindrica and Benincasa hispida were usually free from the

disease. Wide-spread occurrence of the disease on C. melo.

18

C. melo var. utlllssimus, C. maxima, C. moschata, _C. pepo,

L. leucantha and C. cordifolia has been recorded in a

number of districts in Uttar Pradesh. L. cylindrica, C.sativus

and B« hlspidca were also Infected in a number of localities

in the State (Khan, 1972).

d. Symptoms;

Symptoms of powdery mildew are quite conspicuous. In

early infection, tiny, white round, superficial spots appear on

leaves becoming powdery due to the production of enormous

conidia. These white spots increase in number, coalesce and

eventually may cover the leaves. The both surfaces of the

leaf lamina are primarily infected but petioles and tendrils

and stems are also involved in infection when the disease

assumes severity. Fruits usually remain free from infection

even if the plant is heavily infected. But fruits of severely

infected plants ripe prematurely and lack desired texture,

flavour and sugar content. Late-set fruits are often small

and irregular (John and Guy, 1953). Nevertheless, there are

a few reports regarding the infection of fruits. In U.S.A.,

the powdery mildew fungus was found infecting young fruits of

watermelon in a form of powdery mildew pimples (Ivanoff,1957).

Mclean (1970) reported that immature fruits of two lines of

watermelon were infected with powdery mildew. In the Imperial

valley of California, Kontaxis (1977) found powdery mildew

infection on fruits rather than foliage on watermelon, but

vice versa on muskmelon.

19

e. Causal organisms?

Six species of powdery mildew fungi viz,, Erysiphe

cichoracearum DC. ex Merat; Erysiphe communis (Wallr.) Link.;

Erysiphe polygoni (DC.) St. Am.; Erysiphe polyphaga Hammarlund.;

Leveillula taurica (Lev.) Arnaud. and Sphaerotheca fuliginea

(Schlecht. ex Fr.) Poll, are claimed to be recorded in

perithecial stage on cucurbits (Ballantyne, 1975; Khan, 1983).

There are also records of conidial stage (anamorph) of powdery

mildew fungi as Oidium sp. which indicates that the species

involved could not be determined.

Although E. communis and E. polyphaga have been claimed

to occur on cucurbits, their taxonomy and nomenclature on

cucurbits are doubtful and not recognised (Junell, 1965,1957;

Nagy, 1975). E. polyphaga was described in Germany (Hammarlund,

19A5) and was claimed as a causal organism of cucurbit powdery

mildew (Nagy, 1975). Nagy (1975), however, claimed that the

denomination E. polyphaga is not valid and reported that powdery

mildew belonging to E, polyphaga. developing their conidia in

chains, not containing fibrosin bodies, having simple germ

tubes forming longish, club-shaped appressoria may be recognised

as E. cichoracearum. E. polygoni was claimed to occur on

cucurbits in Poland (Schroeter, 1893) and in Japan (Homma,1937).

Since then, these records were not substantiated by any other

reports. Khan (1983) opined that these may be the cases of

mistaken identity.

20

The occurrence of L, taurica on cucurbits is reported

only in a few countries (Table 2). Tarr (1955) recognized

L. taurica causing powdery mildew on Cucurbita maxima in Sudan.

Golovin (1956) recorded Leveillula on vegetable marrow, cucumber

and Cucurbita sp. in U.S.S.R., and proposed a new species,

L, cucurbltacearum for the L. taurica on cucurbits while spliting

''^ L' taurica into species for each host family. The spliting

of L. taurica into different species according to host families

was, however, not recognized (Ballantyne, 1975). Nasyrov (1962)

observed the fungus on vegetable marrow in U.S^S.R. In Kenya,

L* taurica was listed on cucumber (Anon., 1961). Recently

L. taurica was recorded on cucumber in Rumania (Docea and

Fratila, 1980). In other records, I., taurica was reported in

association with other cucurbit powdery mildew fungi. In

U.S.S.R., Gordeeva (1961) and in Bulgaria, Elenkov £t al.(1975)

found L, taurica together with E^ cichoracearum and S.fuliginea

on greenhouse cucumbers. El-Ammari and Khan (1983) reported

occurrence of L. taurica in conidial stage was first reported

from Durgapura, Jaipur (Rajasthan) (Mahrshi and Siradhana,1980).

Ullasa and Amin (1981) also recognised its occurrence on

squash along with _S. fullginea« ^'

The most commonly recorded causal organisms of powdery

mildew of cucurbits in different parts of the world are E.

cichoracearum and S, fuliginea (Hirata, 1968; Ballantyne,1975;

Sitterley, 1978 and Khan, 1983) (Tables 3,^,5,6). Morphological

descriptions of the three species well-recognised to occur on

cucurbits and identified in the presence of their perithecial

stages are as follows:

21

< o M

W

<

O CO

T3 r—I

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(D <H <H •H T)

C •H

to -P •H Xi u O

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c o cd o •H ( «J

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cc;

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c CO

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<:

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to

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CD • H

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r-{ (T3 W D 05 O

0) x: -p

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24

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cu o a> a> JH C5

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03 O to 03 bO 03 T> 03 S

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<t

to

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25

• r-l

o ?

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a> <H <H •H x( a o u <H

0) CC 0) o iS •H X) ^ a o a o c o CO (U

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W a. o ce : 3 w

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» » CD t i to CO J-. -H > . C !-( Qi

X I to -H TZ! •rH X ! QJ CO J O CO S

• i •• " C O

> . - fH -H 5-1 CU CO C CO O bO CO bO C D 3 C CO +^ -C :3 5-, t. +^ S Ci4 O -H

a. .J > ) • • • • CO >> C CO ? H -H -P t^ CO CO rH O +^ D- CO S M CO S

•« * c

CO O • •-H H CO

O <i) U XJ O 3 g CQ CO *

O T ! •> •> C CO

r^ to -H <U rH t i (0 -H CU t< CO X i m x: -H M E-f CO

^ CO •. 0) • CO C to CU

•H -H C P, to -H O. 0) 3 •

•H C C3 to H O bO •H -d S c x: c 0) o a. t-i S: EH

• w M

>, t, CO C CO CJ

• to M

O •H JH CO d)

i H CO m

• k

CO •H c o X) OI

r-( CO

O CO

5 ? tu <o s: 'Ti

26

Erys iphe cichoraicearum DC. ex Merat, in Nouv. f l . env.

P e r l s 1 ed . 2 : p).132, 1981.

ANAMORPH ; Euojidium type

Colonies lamphlgenous , mycelium well developed, evanescent ,

sometimes p e r s i s t e n t and ef fused . Conidia i n c h a i n s , subglobose

or e l l i p s o i d a l , jvacuola te , g r a n u l a t e , 20-40 x 15-21 jim.

TELEOMORPH : C l 4 i s t o t h e c i a dark brown, g rega r ious or s c a t t e r e d ,

subglobose to g l o b o s e , depressed,75-246 jam i n d i ame te r ,

c l e i s t o t h e c i a l i wall c e l l s v a r i a b l e i n s i z e , u s u a l l y 12-39 Jim

in width . Appendages mycel io id , l i g h t brown, sometimes hyal ine

nemerous, den£^>ely interwoven with mycelium, r a r e l y branched,

90-275 Jjm in . 'length. Asci 6-25 in each c l e i s t o t h e c i u m , u sua l l y

18-20; hyal iq 'e , narrowly ovate to broadly o v a t e , r a r e l y sub-

g lobose , morp or l e s s s taoked , 42-90x24-54 jam. Ascospores

h y a l i n e , ovfal to e l l i p s o i d a l , two i n each ascus r a r e l y t h r e e ,

15-42x12-24 jufli in s i z e .

Sphaerotheca f u l i g i n e a (Sch lech t . ex F r . ) P o l l , i n A t t i r .

1 s t . Bot . Univ. Pavia 2 ( 9 ) : 8 , 1905.

ANAMORPH : Euoidium type .

Colonies amphigenous, mycelium hya l i ne , o c c a s i o n a l l y

brown when o l d , u s u a l l y evanascent but sometimes p e r s i s t e n t

forming white c i r c u l a r to i r r e g u l a r pa t ches on the host s u r f a c e .

Conidia i n long cha ins , o f ten with d i s t i n c t f i b r o s i n bod ies ,

e l l i p s o i d a l to b a r r e l shaped, 25-37x14-25 jam,

TELEOMORPH: C l e i s t a t h e c i a s c a t t e r e d to dense ly g r e g a r i o u s ,

66-98 jam in d iameter u s u a l l y under 85 jam; wall c e l l s u s u a l l y

27

over 25 m wide. Appendages variable in number, usually as

long the diameter of the ascocarp, mycelioid, brown, tortuous,

interwoven with mycelium, but sometimes long, nearly straight

and dark brown. Single ascus in each cleistothecium, broadly

elliptic to subglobose, 50-80x30-60 jjm, ascospores 8, ellipsoid

to nearly spherical, 17-22x12-20 jam.

Leveillula taurica (Lev.) Arnaud in Annls. Epiphyt., 7:

92, 1919.

ANAMORPH : Oidiopsis type

Mycelium permeating the host tissue, persistent effused,

densely compact; condiophores emerging through stomata, simple

or branched. Conidia born singly on conidiophores, large predo­

minantly of two distinct shapes-cylindrical and navicular,

varying in size on different hosts, 25-95xlA-20 jjm.

TELEOMORPH j Cleistothecia generally scattered, rarely grega­

rious, often some what embedded in a dense superficial mycelium,

135-250 jam in diameter, globose or becoming concave at maturity,

wall cells polygonal, ^0 jam in diameter. Appendages numerous

hypha-like simple, densely interwoven, short, indistinctly

branched, colourless to olivaceous brown. Asci 20-34 sometimes

less than 20, broadly ovate, stakled, 70-110x25-50 jum. Ascospores

usually 2, large, cylindrical to pyriform sometimes slightly

curved,variable in size 25-40x12-22 jjm.

Identity of the Casual Organisms

A consolidated list of identity situations in different

countries is given in Table 7. Early Europeans mycologists such

-o

(0 •H W CO

XI

c o +J CO

o •H M •H c

28

CU TJ f-. O O

^ CO OJ

• H O

a> CO

o C! OJ 5H OJ tH

ct:

4-> E :3 o u

CO

u 0}

• p

o CO

u CO

x: o

i H CO

• H T J • H

c o o

CO U QV

+ J O CO 5- CO sz o

r-i CO

• H Td • H C O

o

CO i-, 0)

- p

o CO

u CO

x: o

- H CO

• H

r) • H C

o o

CO

u, (b

4-> O CO

u CO x: o

r H CD

• H T; • H C O

o

to tn QJ

- P O CO S-, CO

x: o

H CO

• H T l • H C

o u

!0 I H

Q; - p

o CO

u CO x: o

r H CO

• H

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35

as Leveille (1851), Passerini (1867), Fuckel (1869) and

Jackzewski (I896) diagnosed the causal organism of powdery

mildew of cucurbits as Sphaerotheca castegnei. Later

Humphrey (1392) and Schroeter (1893) in Europe identified it

as Eryslphe cichoracearum and E. polygoni respectively.

Salmon (1898) observed the presence of perithecia on Cucurbita

pepo plants infected with powdery mildew fungus in which each

ascus had two ascospores. This led Salmon to conclude that

the causal organism of powdery mildew was E. cichoracearum rather

than _S. castegnei. Later on, Salmon (1900) examined herbarium

and exsiccati specimens, which had earlier been described as

S, castegnei and observed that specimens lacked perfect stage

and in each case the description was based on imperfect stage.

This finding convinced him the correctness of his earlier

identification and led him to remark, "It is ofcourse possible

that more than one species of Erysiphe occur on these host

plants, and it would be very interesting to note if any example

that perithecia of Sphaerotheca really exists". This emphatic

statement perhaps led to the belief that the powdery mildew

disease on cucurbits is caused by E. cichoracearum. Consequently,

E. cichoracearum came to be known as the causal organism of the

disease for longtime almost throughout the world.

In The Netherlands prior to 1964, E. cichoracearum was

believed to be the only causal organism of the disease.

Dekkar (196I, 1965) reported that E. cichoracearum causes

powdery mildew on cucumbers in the country. Boerema and Van

Kesteren (1964) Identified powdery mildew of cucumber, melon

36

and gherkins as S. fullginea, on the basis of conidial characters,

They also remarked that there appears to be no reliable record

of E. cichoracearum on cucurbits in The Netherlands. Kooistra

(1968) has also observed conidial 'stage of S. fuliginea on

cucumber. Perithecia of S, fuliginea have now been recorded

from Wageningen in the country (Anon., 1965). In Spain, both

species were found where as in Portugal, it was recognised

as Oidium sp. and in Cyprus as E. cichoracearum (Hirata, 1968).

In Malta, E. cichoracearum was reported to occur on cucumbers

(Peralta, 1946-47),

Both _S. fuliginea and E, cichoracearum have been reported

from Bulgaria (Tafradzhiiski, 1959,1961,1963) where the latter

predominates. Recent reports from Bulgaria (Tafradzhiiski,1972;

Lozanov and Vitanov, I960) also confirm this situation. In a

recent reports from Bulgaria, Elenkov et al. (1975) indicated

the existence of Leveillula cucurbitacearum ( = L. taurica) on

cucumber in Plovadic district. E. cichoracearum was earlier

recognised as powdery mildew of cucurbits in Hungary (Ubrizsy,

1946). Studies of Nagy (1970,1972) have undoubtedly established

the existence of both E. cichoracearum and S. fuliginea in

Hungary. Docea and Fratila (1980) observed L. taurica on

cucumbers in Rumania. Earlier, S, fuliginea had been recorded

in perithecial stage in Rumania (Savulescu, 1929). Reports

from Austria by Glaeser (1970,1973,1974) have claimed the

widespread occurrence of E, cichoracearum on cucumber. Studies

of Zacha (1968) and Benada (1974) have established S, fuliginea

as the only organism on cucumber in Czeckoslovakia although

37

E, clchoracearum was ealier claimed to exist. Recently Lebeda

(1983) collected 102 samples from 37 localities on Czeckoslovakia

mainly from cucumber and a few from squash leaves. He identi­

fied E. clchoracearum and S, fuliginea from their anamorphs.

In U.S.S.R. occurrence of both organisms (S.fuliginea

and E. clchoracearum) in perithecial stages on cucurbits was

reported by Deckenback and Koreneff (1927) from Crimea. Since

then a number of reports have indicated the existence of both

the pathogens in U.S.S.R. In some regions of the country

S. fuliginea have,been found to be confined whereas only E.

clchoracearum in other parts. In Moldavia, Armenia, Volga

Basin, Crimea, Azerbaijan, Astrakhan and Bylorussia regions,

existence of both the species has been recorded (Rodi.gin,1936;

Deckenback and Koreneff,1927; Ragimov,195l; Nikiforova,1962;

Teterevnikova-Babayan and Simonyan,1956; Dorozhkin and Kapelyan,

1975). Simonyan (1959), however, reported occurrence of E.

clchoracearum f. cucurbitacearum on cucurbit crops in Armenia.

Rudenko (1968) recognised that in Moldavian conditions

E. clchoracearum f. sp. cucurbitacearum attacks all cucurbits

and _S. fuliginea f, sp. cucurbitacearum cucumber, marrow, pumkin

and muskmelon and both organisms overwintered as cleistocarps

and produced perithecia annually on a number of cucurbits.

Bychenko (1971) and Medvendev (1974) have also confirmed the

existence of both organisms on cucurbits in U.S.S.R. from

Krasnodar region.

Baimuratora (196I) identified the powdery mildew of

cucurbits from Golodnaya steppe as . fuliginea. Osnitskaya (1959)

38

also determined _S, fullglnea as causal agent of cucurbit powdery-

mildew near Moscow, Misiga (1966) identified powdery mildew

on cucumber from Brastilava as E. polyphaga. Golovin (1956)

established a new species of Leveillula viz., L, cucurbitacearum

on cucurbits in U.S.S.R. Gordeeva (1961) observed L. taurica

along with S» fuliginea and E. cichoracearum on cucurbit in

U.S.S.R, L. taurica was also reported to occur on cucurbits in

U.S.S.R. by Nasyrov (1962).

In Germany, Roder (1937) reported occurrence of E.

cichoracearum on outdoor cucumber near Berlin. Bremer (19^0)

observed E. cichoracearum as the agent of cucumber mildew in

central Germany. Hjttenbach (1951) for the first time indicated

the existence of both S» fuliginea and E. cichoracearum in West

Germany. He, however, emphasized the predominance of E.

cichoracearum. The recent observation of E. cichoracearum in

perithecial stage and _S. fuliginea in conidial stage concomi­

tantly on cucumbers by Schlosser (1972) near Bonn is noteworthy.

This confirms the existence of both organisms in West Germany.

Schlosser (1976,a,b) based on a survey of the distribution of

^. fuliginea and E, cichoracearum in the Federal Republic of

Germany (West Germany) reported that _S. fuliginea prevailed in

glasshouse conditions on cucumber, and E. cichoracearum under

field conditions. Cruger and Meyer (1976) observed the both

powdeiymildew agents, E. cichoracearum and _S. fuliginea on

cucurbits. They also noted that E. cichoracearum was found

only in outdoor conditions while _S. fuliginea on both outdoor

and glasshouse.

39

After Salmon's observation of perithecia of E.cichora-

cearum in 1898, Reed (1936) and Williams '(19 1) confirmed it

as the causal organism of cucumber mildew in England. Keyworth

(1959) also recorded its occurrence on cucumber and vegetable

marrow; and Stone (1959) on cucumber. Zaracovitis (1965),

however, in his studies on conidial characters, identified

powdery mildew on cucumber collected from Berkshire as

S. fuliginea. A recent report has also indicated its existence

on cucumber in U.K.(Spencer al., 1975). E. cichoracearum

is reported to infect cucurbits particularly vegetable marrow

in Switzerland (Mayor, 19A7). Besides, S. fuliginea is also

known to exist in Switzerland (Hirata, 1968). Blumer (1951,1960),

however, claimed that E. polyphaga also infects cucumber in

Switzerland. In France, Viennot-Bourgin (1958) recorded E.

cichoracearum on Cucumis melo and C. sativus in perithecial

stage. Lafon jet al, (1966) identified E. cichoracearum f.

cucurbitae as the organism responsible for the disease in

France. Landel (1961) had also described it as E. cichoracearum

but an earlier report by Lafon (1966) has indicated the

occurence of both, E. cichoracearum and 5. fuliginea on

cucumber in France. Marcelli (19^9) observed both E.

cichoracearum and S. fuliginea on cucurbits in Italy, S.fuliginea

being widespread and E. cichoracearum only on Cucurbita maxima.

Locci and Bisiach (1972) also observed _S. fuliginea on cucumber

in Italy. Perithecial stage of . fuliginea from Turin, Italy

is also on record (Blumer, 1933).

AO

Gjaerum (1956) referred E. clchoracearum on greenhouse

cucumber in Norway. Banga (1955) identified cucumber mildew

as E. cichoracearum in Sweden. Junell (1967) obtained peithe-

cial stage of E, cichoracearum in Sweden. E. cichoracearum

and S, fuliginea are listed on cucurbits in Finland. However,

in Denmark, only E. cichoracearum is reported. Ristic (1985)

observed that both the upper and lower surface of leaves of

cucumber were attacked. The pathogen often appeared on leaves

or the stem. Fruit infection was rare. Perithecia rarely formed,

usually had 2-3 asci each generally with 2 ascospores indicating

involvement of E. cichoracearum.

In U.S.A. upto 1963 in all reports, the disease has been

assigned to only E, cichoracearum on cucurbits although its

perfect stage was seldom found. Perithecia of E. cichoracearum

were recorded on cucurbits from Massachusetts and Wisconsin by

Humphries (1893) and Reed (1908) respectively. Jagger (1926)

identified the powdery mildew of muskmelon in the Imperial

Valley of California as E. cichoracearum. Middleton and

Yarwood (19^6) observed the appearance of E. cichoracearum on

melons in California, Barrat (19A2) at the New Hampshire

Horticulture farm; Pryor and Whittaker (19^2) at the U.S.

Horticulture Field Station, Lajolla, California; Walker and

Weber (1949) and Conover (1957) in Florida; and Ivonoff (1957)

in Mississippi. Randall and Menzies (1956) recorded perithecia

of E. cichoracearum for the first time in recent years, on

cucumbers in the Yakima Valley, Washington in 195^. Blasquez

(1970) and Jones (1974) recorded E, cichoracearum on cucurbits

in Florida.

41

Kable and Ballantyne (1963) for the first time in U.S.A.

identified the powdery mildew of cucurbits in Ithaca district,

New York state on the basis of conidial characters as S.fuliginea

and claimed that this may be prevalent in other areas of the

country. Yarwood and Gardner (1964) suggested that in California

the powdery mildew on cucurbits was . fuliglnea. Since then

a number of reports indicated the existence of . fuliginea on

cucurbits in conidial stage in different part of U.S.A.

Ellert (1966) obtained Oidium sp, resembling _S. fuliginea.

Schroeder and Prowidenti (1968) observed S» fuliginea on

squash and cucumber at the New York State Agriculture Experiment

Station. Paulus et al. (1969, 1972) also observed _S. fuliginea

on contaloupe at the University of California, Riverside and

Lajolla, California. ^, fuliginea has been found on cucurbits

in Georgia (Sowell and Clark 1971), Iowa (Clark, 1975); and

•Wisconsin (Shanmugasundarum et al., 1971)o All these records

are based on conidial characters. Kontaxis (1979) recently

found the perithecial stage of _S. fuliginea on Cucurbita pepo

in the Imperial Valley, California. This emphatically substan­

tiated the earlier reports of occurrence of S. fuliginea in

U.S.A. and fully established existence of . fuliginea on

cucurbits in the country. He remarked that the causal agent

for the powdery mildew of squash, probably all cucurbits in

California and possibly in the United States is _S. fuliginea

and not E. cichoracearum.

In Canada, McKeen (1954) mentioned E. cichoracearum on

cucurbits in Ontario region. Fisher (1959) also referred to

powdery mildew of greenhouse cucumbers as E, cichoracearum.

42

A ministry of Agriculture report for the year 1953 mentioned

E, cichoracearum responsible for powdery mildew of autumn

cucumbers in Essex County, Ontario. Similar report was made

by Bradbury and Fisher (1963) from Ontario, There appears to

be no published record of S.fuliginea in Canada as no such

information is apparently available in literature.

In South America, a Bolivian list of diseases of

temperate crops, included E. cichoracearum on cucurbits

(Bell and Alandia,1957). Revilla (1955) had also mentioned

the powdery mildew of melon, pumpkin and cucumbers as E,

cichoracearum. Rochelle (1972) reported the occurrence of

E. cichoracearum on squash and marrow in Brazil. E.cichoracearum

is also recognised as causal organism in Venezuela and Uruguayo

However, it is mentioned only as Oidium sp. in Argentina (Hirata,

1968). Powdery mildew of £. melo in Peru was recognised by

Mont and Villon (1975) as E. cichoracearum. There appears to

be no record of _S. fuliginea from South America. Similarly

there is no report of perithecia of cucurbit powdery mildew

from any country in South America. Possibly no attempt has

been made to identify the causal organism taking into considera­

tion the divergence of S»^uliginea as dominant species in many

different parts of the world and E. cichoracearum is traditio- '

nally believed as the causal species,

De Carvalho (1948) included E. cichoracearum as causal %

organism of powdery mildew of cucumber and other cucurbits while

listing the plant pathogens of economic importance in Mozambique.

In Transvaal province of South Africa, Gorter (1966) on the basis

43

of conidial characters concluded that powdery mildew on cucurbits

Is caused by S. fuliginea and claimed that _S. fuliginea is the

only or most prevalent cucurbit powdery mildew in South Africa.

Although Du Toit (19^8) had earlier reported that cucurbits

in the Western and South Western Cape Province of South Africa

suffer from powdery mildew caused by E. cichoracearum. A

recent report from South Africa by Gorter (1974) further

established the existence of S, fuliginea in the country. The

powdery mildew of cucurbits in Egypt attacking all species

caused by E. cichoracearum (Fikry, 1936). Moursi and Sirry

(1956) claimed the attack of E. cichoracearum on squash through­

out the year in Egypt. Elarosi and Wasfly (1971) also found

E. cichoracearum on vegetable marrow in Alaxandria. Similar

observations were made by Khadr and Abdu (1972) in Giza.

Recently El-Kazaz (1983) surveyed various parts of Egypt and

noted the presence of _S. fuliginea on the basis of presence

of fibrosin bodies in conidia. In Sudan, Tarr (1952,1955)

reported the widespread occurrence of _S. fuliginea and L.taurica

on cucurbits and other vegetables. Later, Nour (1957, 1959)

also recorded the presence of _S. fuliginea on vegetable marrow,

pumpkin, cucumber and melon. He further pointed out the pre­

valence of this fungus in the fields during winter in Sudan.

Omer (1972) has also obtained conidial stage of S, fuliginea

on cucumiDers in Sudan.

In Libya, Pucci (1965) regarded powdery mildew on

watermelon as E. cichoracearum. Kranz (1962) also recognised'

powdery mildew on certain cucurbits in the Eastern region of

the country as E. cichoracearum. Khan (1981), for the first

44

time, recognised the occurrence of conidial stage of S.fuliginea

on cucumbers in the country. Later, its perfect stage was

found on C. pepo (El-Ammari and Khan, 1985). However,

E. cichoracearum was found in cucumber in greenhouses near

Benghazi. Further, L. taurica was recorded on cucumber in

areas both in Western and Eastern parts of the country. It

was recognized that the symptoms of powdery mildew on cucumbers

caused by L, taurica were very specific and markedly different

from those caused by S, fuliginea and E. cichoracearum (El-Aramari,

1983; El-Ammari and Khan, 1983). Perithecial stage of

E. cichoracearum or of L. taurica were, however,not found.

Identifications were based on conidial stages. A Kenya Annual

Report, Department of Agriculture 1958 enlisted E. cichoracearum

as an agent continuously hampering the cultivation of cucurbits.

L. taurica is also reported from cucurbits (Hirata, 1968).

S. fuliginea has been recognised to cause problems to vegetable

crops in Malawi (Spurling 1973). Morocco, Ethiopia, Senegal,

Uganda, Tanzania, Zambia, Zimbabwe, Medagascar and Mauritius

are enlisted to have E. cichoracearum on cucurbits, whereas

Ghana, Tunisia, Sierra, Leone and Canary Island are known to

have Oidium sp. (Hirata, 1968). Khan (1983) remarked that

perhaps recognition of E. cicoracearum in these countries is

based on tradition rather than proper investigations. *

In Australia, Blackford (1943) reported the occurrence

of E. cichoracearum on cucumbers in Queensland. Agriculture

Gazette of the New South Wales (1948) also recognised

E. cichoracearum as cucurbit powdery mildew. However, after the

45

reports of Clare (1958) who identified the powdery mildew of a

number of cucurbits in South Eastern Queensland as _S- fuliginea

investigations were made to determine whether powdery mildew

in the New South Wales is caused by _S. fuliginea or E.

cichoracearum, Ballantyne (1963) successfully employed the

conidial characters in identifications, and established

^, fuliginea as the only causal organism of cucurbit powdery

mildew in New South Wales. McNish (1967) also recorded the

widespread occurrence of , fuliginea on cucurbits in Western

Australia. More recently, Ballantyne (1975) after an extensive

study of 150 collections of powdery mildew made in New South

Wales on numerous cucurbits established the existence and

predominance of _s. fuliginea in Australia. The existence of

_S. fuliginea in New Zealand has been established by the occurrence

of its perithecia on £, pepo (Dingley, 1959; Boeswinkel,1976).

In Asia also, it was believed that E. cichoracearum is

responsible for the disease in most of the countries, apparently

without proper verification. However, there are reports of

^. fuliginea from several Asian countries. In Turkey, Bremer

et al. (1947) reported _S. fuliginea in perithecial stage on

three cucurbits. In Iran, _S. fuliginea has been claimed to

exist on all cucurbits in subtropical regions of the northern

part of the country (Esfandiari, 1947). Allison (1952)

identified E. cichoracearum as powdery mildew of cucurbits in

Iraq. E. cichoracearum was claimed to exist on cucurbits in

Saudi Arabia (Anon., 1976). But recently, Abul-Hayja and

Trabulusi (1981) obsei-ved perithecia at S. fuliginea on squash

46

and cucumber and claimed that probably all cucurbits in Saudi

Arabia are infected by _S. fuliginea and not by E.cichoracearum.

In Israel, Rayss (1947), Palti (1962) and Rudich et al.(1969)

recognised S. fullglnea on cucurbits although earlier reports

of powdery mildew on cucumber and vegetable marrow by Reichert

et al. (1943) from Palestine and of cucumbers and melons by

Peleg (1953) had recognised it as E, cichoracearum. Thompson

(1933) recorded _E, cichoracearum in Malaysia and Singapore,

Chin e_t £l_. (1959) from China diagnosed powdery mildew of

cucumbers as S, fuliginea. Ifeshioka (1937) and Sawada (1959)

also recognised ^, fuliginea as the agent of the disease in

Formosa (Taiwan), In Japan, Uozumi and Yoshi (1952) emphatically

recognised _S. fuliginea as the only pathogen causing powdery

mildew of Cucurbits in Fukuoka region of Japan. They also

observed occasional production of perithecia. Katusuki (1955)

also identified _S. fuliginea on cucumbers in Yaku Island,

Kysushu, Japan. Recent report from Japan, however, indicated

the existence of both _S. fuliginea and E. cichoracearum

(Nomura, 1974).

E, cichoracearum is mentioned to occur in Nepal,

Afghanistan, Lebanon and Jordan whereas _S. fuliginea is

recognised in Pakistan. Both species are, however, known to

occur in Korea (Hirata, 1968). Powdery mildew of cucurbits

in Philippines, Indonesia, Thailand, Cambodia, Burma, and Ceylon

is referred to as Oidium sp. (Hirata, 1968), perhaps due to the

lack of proper investigations in this region of Asia.

47

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49

Three causal organisms viz., _S. luliginea, E.ciohoracearum

and L, taurica reported onto cucurbits from dilferent States of

India (Table 8), Butler (1918) reported E. cichoracearum on

_C. cordifolia, Trichosanthes dioica and Momordlca balsamina from

Bihar, He found pei jthecia of E. cichoracearum. In a later

study in Bihar, Khan (1977) found _S. fuli^inea on a number of

cucurbits and E» cichoracearum on C.cordifolia. He identified

the causal organisms on the basis of conidial as well as

perithecial characters. Jhooty (1967) identified the occurrence

of _S. fulipjinea on cucurbits in Punjab, based on conidial

characters. Sohi and Nayar (1969) reported _S, fuliginea on

C. moschata in Hlmachal Pradesh on the basis of perithecial

• characters. Khan £t al . (1974) recognized _S« fuli .inea occurring

on a number of cucurbits in Jammu and Kashmirc They identified

the causal organism on the basis of conidial as well as perithe­

cial characters. Dave e_t al. (1971) and Khosla £t al, (1974)

recorded E, cichoracearum and _S. fulifilnea occurring on

cucurbits in Madhya Pradesh. They identified the causal

organisms on the basis of perithecial characters. Siradhana

and Chaudhari (1972) reported the occurrence of _S. fuliginea and

E. cichoracearum on cucurbits in Rajasthan. They identified

the causal organisms on the basis of perithecial characters,

Malik _et al, (1973) obtained E. cichoracearum on B, hispida

from Udaipur (Rajasthan). Maharshi and Siradhana (1980)

recorded the occurrence of L, taurica (= Oidiopsis taurica)

on cucurbits from Rajasthan on the basis of conidial characters.

Butler (1918), Khan and Khan (1970), Khan _et a]^. (1971),

Sharma (1973) and Malik £t al.. (1973) reported S. fuliginea

50

and E, clchoracearum infecting a number of cucurbits in Uttar

Pradesh. They identified the causal organisms on the basis of

conidial as well as perithecial characters. Ullasa and Amin

(1981) reported occurrence of L. taurica and _S. fuliginea on

squash in Karnataka based on conidial characters (Table 12),

Values of different structures of conidial stage (anamorph)

on the taxonomy of powdery mildews of cucurbits;

Morphological characters and dimensions of different

structures consistuting the anamorph (conidial stage) is con­

sidered valuable in the taxonomy of powdery mildew of cucurbits

(Yarwood, 1978; Sitterly, 1978; Khan, 1983). Some such

structures and their features are summarized belowj

1. Mycelium : The mycelium of E. clchoracearum and S.fuliginea

is superficial (external) except for that of L. taurica. In

the former case, mycelium consists of a net work of colourless

hyphae abundantly present on the surface of the infected parts

of the host. In L. taurica, mycelium is endophytic (internal),

spreading between the mesophyll cells of the leaf. This is

very important distinguishing character for Leveillula.

2, Conidiophores : The types of conidiophores observed in

powdery mildews of cucurbits are either branched or unbranched;

those with conidia borne singly or those borne in chains; those

with fibrosin or without fibrosin bodies; and those with conidia

of one shape or those with various shapes (Yarwood, 1978;

Khan, 1983). The conidiophores of E. clchoracearum and

51

S. fullginea are unbranched, bearing a chain of conidia

(Euoidium type) while those of L. taurica the conidiophore

is often branched (Oidiopsis type) with two types of conidia

(navicular and cylindrical). They emerge through stomata.

These features of conidiophores are helpful in differentiating

L. taurica from S. fuliginea or E. cichoracearum.

3. Conidia : Shape and size of conidia are sometime advocated

to be used in taxonomy of the species.

a. Shape :- There are suggestions to use the shape of conidia

to distinguish the different genera of powdery mildews involved

in the development of disease on cucurbits. The shape of

conidia of _S. fuliginea is ellipsoidal or at least with a

tendency towards this shape where as those of E, cichoracearum

are barrel-shaped with a tendency towards cylindrical forms

(Khan, 1983). L. taurica produces two distinct kinds of

conidia viz., cylindrical and navicular. This is a very pro­

minent feature of conidia of L. taurica and can be easily

distinguished from other species,

b. Size :- The size of conidia is often used in the taxonomy

of powdery mildews (Allison, 1931; Clare, 1958; Boerema and

Van Kesteran, 1964; Jhooty, 1967; Nagy, 1979). Size of conidia-

is fairly constant for a given host in a given environment

(Blumer, 1922). But,the utility of this character seems

doubtful as the dimensions of conidia are greatly influenced by

a number of factor including relative humidity, temperature;

host and its nutritional status (Yarwood, 1978; Khan, 1983).

S2

4. Flbrosln bodies : Well developed fibrosin bodies (2opf,1887)

occurs in the condia and conidiophores of S, fuliginea but

are absent from E. cichoracearum (Ballantyre, 1953; Clare,1964;

Nagy, 1970). This character is apparently useful and seems

to be highly reliable for distinguishing S. fuliginea from

E. cichoracearum. But there are records of S, fuliginea which

lack fibrosin bodies. Yarwood (1978) stated that he agreed

with the utility of this character but felt that this might

have been over emphasized. He remarked that he has observed

fibrosin bodies forming cultures of . fuliginea which do not

always have them in every conidium. He noticed in his culture

of S. fuliginea 4-8 fibrosin bodies in each conidium produced

on the upper surface of the cotyledons and true leaves in the

greenhouse at about 20*0. But on the lower surface fibrosin

bodies were sometimes absent. He noticed that percentage of

conidia with fibrosin bodies were as low as 20% on outdoor

squash in Berkley, U.S.A. He further noticed that temperature

was a factor in the incidence of fibrosin bodies in conidia.

He observed that incidence of fibrosin bodies on cucumber in

greenhouse was lower at 16«»C than at 20*0, 24«C or 28'C. In

other species of Sphaerotheca for example in . lanestris the

percentage of conidia with fibrosin bodies was as low as 30%

on Quercus velutina in 1975. These observations of Yarwood

indicate that the presence and absence of fibrosin bodies in

conidia, their incidence and number are influenced by environ­

mental factors, age of the host as well as the species of

Sphaerotheca involved. This creates doubt with regard to

53

utility of fibrosin bodies in identification of Sphaerotheca

species. This aspect needs further examination and thorough

investigations.

5. Germination : Clare (1964) and Zaracovitis (1965) distin­

guished the powdery mildews by the method of germination of the

conidia. S. fuliginea produces forked germ tube while those of

E. cichoracearum produces simple germ tube with well developed

distinct appressoria. They successfully used this clubshaped

appressoria as a taxonomic character,

b. Identification of the pathogens in absence of teleomorphs;

Identification based on perithecial characters is easy

but perithecia are rarely formed in nature. Then identifications

are based on conidial characters. But conidial stages of

S, fuliginea and E. cichoracearum exhibit great similarities.

Conidia in both are born in long chains on same kind of condi-

ophores. Apparently there is no distinction in symptoms of

the disease caused by them on cucurbits. This situation has

caused great deal of confusion regarding identity of the species

causing powdery mildew on cucurbits in different parts of the

world, or in different areas or within the same area in a given

country.

Sawada (191A) proposed a scheme for classification of

Erysiphaceae based on conidial stage. The characters recognised

as most useful in identification were formation of conidia

singly or in chains, shape and dimensions of conidia and

condiophores, presence of fibrosin bodies and the type of

54

vacuoles, Yarwood (1957) remarked that the method of germina­

tion of conidia is also distinguishing character, though it

perhaps may not be recommended for taxonomic purposes. He,

however, devised a key based on conidial stage characters for

identification of genera and species of powdery mildews in

the absence of perithecia (Yarwood, 1973).

. Khan (1983) concluded that there is a great degree of

agreement that the presence or absence of well developed fib-

rosin bodies and mode of germination of conidia are useful

criteria for distinction between E, cichoracearum and S.fuliginea.

The extensive study of Ballantyne (1975) in which she examined

a large number of samples collected from different parts in

Australia subtantiated this contention. Disagreement, however,

exists on the utility of conidial dimensions, rate of germi­

nation and germination in relation to moisture stress. Conidial

germination characters have been successfully adopted in diffe­

rentiating powdery mildews of cucurbits. Hashioka (1937) and

Hirata (1955) observed that _S. fuliginea was unique in producing

forked germ tube. Zaracovitls (1965) used conidial germination in

identifying imperfect state of powdery mildews. He observed

that conidia of E. cichoracearum on germination on glass produced

simple germ tubes with thick walled club-shaped appressoria

where as those of _S. fuliginea produced no well-differentiated

appressoria and a number of conidia formed forked germ tubes.

Ballantyne (1975) observed that all conidia of . fuliginea do

not produce forked germ tubes but percentage of forking ranges

from 3-60 percent with more specimens in the range of 3-5 per cent.

55

Fibrosin bodies, also designated as Corpuscles de Zopf

nemed after Zopf (1887) who first reported them from the

conidia and conidiophores of Podosphaera oxyacanthae, were

recognised valuable in taxonomy of powdery mildews by Foex

(1912,1925) and Bouwens (1927). Blumer (1933) and Homma (1937)

considered presence or absence of fibrosin bodies valuable in

distinguishing conidial stages of E. cichoracearum and

S. fuliginea on cucurbits. Hashioka (1937), Uozurai and Yoshi

(1952), Sawada (1959), Dingley (1959), Clare (1958, 1964),

Boerema and Van Kesteren (1964), Kable and Ballantyne (1963)

and Ballantyne (I963, 1975) have recognised the significance of

fibrosin bodies in differentiation of S. fuliginea and

E, cichoracearum, Fibrosin bodies were also reported in

E. cichoracearum by Klika (1922) without specifying the charac­

teristic form. But this has not been substantiated by later

reports. Bouwens (1924), Clare (1958) Boerema and Van Kesteren

(1964) Jhooty (1967) and Nagy (1979) considered that dimensions

of conidia are of taxonomic importance for these species.

Yarwood (1957, 1978), however, expressed doubts about the

utility of dimensions of conidia in their taxonomy as these

features are greatly influenced by a number of factors including

relative humidity, temperature, host and nutritional status.

Khan (1983) proposed, on the basis of his fifteen years experie­

nce of working with these pathogens, that in most of the

specimens the shape of conidia in . fuliginea is ellipsoidal

or at least with a tendency towards this shape where as those

of E. cichoracearum are barrel-shaped with a tendency towards

56

cylindrical form. Similar observations have been reported by

Nagy (1970). Jhooty (1967) concluded that in general conidia

of E. cichoracearum are much longer than those of _S. fuliginea.

Nagy (1970) used the conidial dimensions as a character of

differentiation and found that the length-width ratios of the

two species were significantly different. Schlosser (1976b)

recommended the determination of fibrosin bodies as standard

procedure of differentiation of the two species. Sitterly (1978)

suggested that conidial characters can be used for positive

identification of the causal organism for the purpose of

eliminating taxonomic confusion.

In addition to the conidial characters, Khan (1978)

proposed the use of Coccinia cordifolia and Lagenaria leucantha

as prospective differential hosts to aid in distinguishing

between _S. fuliginea and E, cichoracearum.

Identification of L. taurica in conidial stage is not

difficult because of characteristic symptoms on the host,

internal mycelium, conidiophores emerging through stomata,

bearing single conidia and formation of two kinds of conidia.

In the absence of perithecia, the identity of the powdery

mildew of cucurbits has been established in a number of coun­

tries based on conidial measurements, germination rates, germi­

nation in relation to moisture stress, absence and presence of

fibrosin bodies. Clare (1958), in Australia; Dingley (1959)

in New Zealand; Boerema and Van Kesteren (1964) and Kooistra

(1968) in The Netherlands; Nagy (1970) in Hungary; Kable and

Ballantyne (1963); Yarwood and Gardner (1964); Sowell and

57

Clark (1971); Clark (1975) and Shanmugasumdaran et al. (1971)

in U.S.A.; Schlosser (1972) and Cruger and Meyer (1976) in

West Germany; Gorter (1966) in South Africa; Viennot-Bourgin

(1971) in France and Janke £t a].. (1977) in East Germany and

Jhooty (1967) in Punjab (India) have established their identity

on the basis of conidial characters.

Host Range and Host Specificity

A large number of cultivated and wild plant species

have been recorded as hosts of the members of Erysiphaceae.

Salmon (1900) in his "Monograph of the Erysiphaceae" listed

about 1500 plant species, as hosts of powdery mildews.

Weiss (1950) found powdery mildews on 13^0 out of 3100 host

species given in U.S.D.A. index of plant diseases. Blumer

(1967) listed powdery mildews on 1928 plant species of angio-

sperms.

§.• fuliginea is considered as a serious pathogen of

cucurbits and certain non-cucurbits. Salmon (1900) mentioned

in his monograph that _S. fuliginea attacked 103 species

belonging to 55 genera in 18 different families. The list,

however, did not include any member of the family Cucurbitaceae.

Blumer (1967) listed 256 plant species belonging to 72 genera .

in 12 families as the hosts of E. cichoracearum and 110 species

belonging to 42 genera in 16 families as hosts of _S. fuliginea.

Of these, Cucumis melo, C. metuliferus, C. myriocarpus,

C. prophaterum. C. sativus, Cucurbita flcifolia, C. maxima,

C. pepo, Cs turbaniformis, C, verrucosa. Lagenaria vulgaris

58

and Thladiantha dubia of the family Cucurbitaceae were listed

as hosts of E. clchoracearum and £. melo, _C. sativus, C. maxima,

C. pepo, C. verrucosa and L. leucantha of the family Cucurbi­

taceae as hosts of _S. fulif;inea.

Foex (1924) recognised ^. fuliginea on Erodium malacoides

(Geraniaceae); Buchwald (1936) on Veronica andersonil and

V. myrtifolia (Scrophulariaceae); Rud (1938), Moore (1952),

Williamson (1953), Eliade (1960), Akhundev et al. (1963) and

Anonymous (1964) on Calendula officinalis (Compositae); Tai

(1936) on Phaseolus vulpiaris, P. mungo and cowpea (Leguminosae);

Ikata (1951) on P. angularis; Viennot-Bourgin (1969) on

Phaseolus species; Cheremisinov (1951) on Taraxacum sp.

(Compositae); Tarr (1954) on Sesamum indicum (Pedaliaceae);

Ifegen (1952) on Pedicularis labradorica (Scrophulariaceae);

Dingley and Brien (1956) on Coriaria angustissima and £,

thymifolia (Coriariaceae); Morochkovskii (1958) on Scabiasa

ochroleuca (Dipsacaceae); Vasudeva (1957-58) on Cosmos sp.

(Compositae); Devarennes £t al.(1964) and Jhooty (1965) on

Zinnia species; and Kowalski (1966) on Adonia vernalis

(Ranunculaceae), Movsesyan (1967) observed _S. fuliginea f.

dahliae on Dahlia variabilis (Compositae). Alcorn(l968) and

Munjal and Kapoor (1973) observed _S. fuliginea on Garica papaya

(Caricaceae). Hirata (1966) and Blumer (1967) listed

^. fuliginea on Helianthus annuus. Khan and Faraj (1982)

observed it on Calendula officinalis and _C. arvensis in Libya

besides on a number of cucurbits. It was also noticed on

Bideus bipinnata (Khan, 1982).

59

Kapoor (1967) listed _S. fuliginea on Bray a sp.,

Capsella sp., Parrya sp.. Glycine max, Plantago sp., Mimulus

sp., Hioscyamus ni^er, Physalis alkekengi and Solanum melongena.

Vasudeva (i960) included 7 plant species at hosts of

_S. fuliginea viz., Bidens pilosa, Siegesbeckia orientalis.

Taraxacum officinala (Compositae); Cucurbita maxima, G.moschata

and Lagenaria leucantha (Cucurbitaceae) and Phaseolus vulgaris

(Leguminosae). Tilak and Ramchandra Rao (1967) added 5 hosts

of this fungus namely, Parthenium hysterophorus, Helianthus

annuus and Seneclo grahmis (Compositae); Impatiens balsamina

(Balsaminaceae); Potentilla eriocarpa (Rosaceae). Sarbhoy et al.

(197A) added Striga densiflora, _S. lutea (Scrophulariaceae)

and Dimorphotheca senuali (Compositae) in this host listo

Ducomet (1921), Menzies (1950), Huttenbach (1951),

Thigin (1954), Venkatakrishniah (1954) and Dingley (1960)

reported E. cichoracearum on Solanum tuberosum and Penstemon

hart-wigii; Thigin (1954) on S. demissum; D' Angremond (1924)

on Heliotropium indicum; Schwarz (1926) on Physalis minime;

Zaprometoff (1925) Jackzewski (1927), Brundza (1933) and

Darpoux (1945) on Papaver somniferum; Dadayeva (1930) on

Linum usitatissimum and Howard (1934) on Felicia amelloides

(Aster rotundifolius). Milivtzova (1937), Darpoux (1945),

Zimmer (1961) and Mc Cain (1962) reported E. cichoracearum on

Carthamus tinctorius; MacDonald (1939) on Cineraria; Moore (1956)

on Capsicum; Corner (1956) on Begonia; Yarwood and Gardner (1964)

on Acaena fissistipula, Bacharis pipularis, Fraxinus americana

and Scrophularla californica; Eliade (1966) on petunia hybrida

60

and P. suffulta; Malay and Skotland (1969) on Mentha cordiaca.

Byzova (1961) reported E. cichoracearum f. sp. menthae on

Mentha austrica f. sp. trifolil, Trifolium pratense f. sp.

medicaginls and Medicago falcata. Khan (I960) found E.

cichoracearum on Hedypnois cretica. Zinnia elesans and Souchus

oleraceous in Libya. It was also observed on Amberboa lippii

(Khan and Mussa, 1979) and Chrysanthimum carina turn (Khan and

Paraj, 1982) in Libya.

E. cichoracearum was listed on Basella alba, Garthamus

tinctorius, Eritrichium rupestris, Galium verum, Helianthus

annuus, Mangifera indica, Nicotiana tabacum, Flantagd

braehyphylla, P. major, Papaver somniferum, Verbena sp.,

Veronica bilova and Zinnia elegans by Vasudeva (I960)* It was

observed on Mentha arvensis by Ganguly and Fandotra (1963-1964);

and on Phvochlaina praelta (Hyoscyamus praetens) by Lall and

Gupta (1965). In C.M.I, description of the species, it was

listed on Apocynum sp., Fraxinus excelcior; Mimulus sp.,

Digitalis, sp., Vinca sp. and Antirrhinum orontium by Kapoor

(1967). Jain (1969) found it on Centuria moschata and on

Helipterum (H. roseum and H. album). Prasada e_t aJ. (1968)

regarded Helianthus annuus as host of _S. fuliginea.

Kapoor (1967), in C.M.I, descriptions of the species,

regarded _S. fuliginea as the causal species attacking cucurbits

in general, while E. cichoracearum on composites. Khan and

Khan (1970) observed _S. fuliginea on Cucumis sativus,

Lagenaria leucantha. Luffa acutangula, Melothria maderaspatana

and Cucurbita moschata in India. Khan et al_. (1971, 1972)

61

later concluded that under Indian conditions _S. fulifilnea

attacked mostly cultivated curubits. Sivakami e_t al_. (1S72)

observed Gucumis spp. (cucumber, muskmelon and longmelon)

Cucurbita sp. (pumpkin) and Lagenaria sp. (bottle gourd) as

hosts of _S. fuliginea. A number of such reports from other

parts of India indicated that _S. fuliginea is present on a

large number of cultivated cucurbits in India (Mathur £t £l_.,

1971; Dave_et al., 1971; Siradhana and Chaudhari, 1972; Khan

£tal., 1972; Khosla et a]^., 1974; Khan, 1977).

Salmon (1900) in his monograph on Erysiphaceae listed

15 species of plants in 12 genera belonging to 5 different

families as common hosts for both E. cichoracearum and

_S. fuliginea. No member of the family Cucurbitaceae, however,

appeared in this host list. Huttenbach (1951) from Germany

claimed that E. cichoracearum and _S. fuliginea both occured

on cucurbits. Nikiforova (1962) from Bulgaria reported that

both these fungi existed together on cucurbits. Blumer (1967)

enlisted Cucurmls melo, C. sativus, Cucurbita maxima, £. pepo,

_C. verrucosa as common hosts of both the fungi. Rudenko (1968)

from Moldavia, U.S.S.R., claimed that E. cichoracearum f. sp.

cucurbitacearum attacked all the cucurbits and S. fuliginea

f. sp. cucurbitacearum cucumber, marrow, pumpkin, melon and but

not watermelon. Hirata (1966) and Blumer (1967) listed both

E. cichoracearum and S- fuliginea on Helianthus annuus.

Vasudeva (i960) included 24 plant species as the hosts of

E. cichoracearum and 7 of S^, fuliginea. Bryonopsis laciniosa,

Citrullus vulgaris. Coccinia indica, C. cordifolia, Cucumis melo.

62

C* sativus, Cucurblta sp., Momordica balsamlna, Trichosanthes

angulna and T. dloica were listed as congenial hosts of

E. cichoracearum and L. leucantha, Cucurbita maxima and

C. moschata congenial for _S. fuliginea. Rajendran (1965)

reported E. cichoracearum on bottle gourd (Lagenaria vulgaris)•

In an analysis of literature on host range studies, Khan

(1972) listed Cucumis melo, _C. sativus, Cucurbita maxima,

jC. pepo, and C, verrucosa amongst cucurbits and Abelmoschus

esculentus, Adenostyles glabra, Arctium ma .jus. Calendula

officianalis, Chrysanthemi^ carinaturn, Cichorium intybus,

Crepis paludosa, Gaillardia aristata, Helianthus annus,

_H. debiliSf Hieracium prenanthoides, Hydrophyllum virginicum

Lapsana communis, Leontodon autumnalis, L. hispidus, Prenathes

alba, P. purpurea, Phlox divaricata, Plantago lanceolata,

P, media. Taraxacum officinale. Prunella vulgaris, Vernonia

noveboracensis, Xanthium canadense, X, italicum, X. spinosum,

X. strumarium amongst non-cucurbits as common hosts for both

E. cichoracearum and S, fuliginea.

A number of studies have been carried out on host

specialization of E. cichoracearum and _S. fuliginea. Reed (1908)

provided evidence of cross infection between cucumber and

sunflower isolates of E. cichoracearum. Yarwood (1956) showed

that the isolates of E. cichoracearum from sunflower, squash,

hollyhock, dahlia, lippia, Picris echoldes and Nicotiana

affinis infected cucumbers, though not equally. Miller and

Barrett (1931), on the other hand, showed that forms on cucumber

and sunflov er did not cross infect. Schmitt (1955) confirmed

63

the latter findings and showed that Zinnia strain of E.

cichoracearum had a wider host range than the forms on Inula,

Helianthus, Cerianthe, Phlox or cucurbits. Zinnia isolate

attacked Z. elegans, Z. pauciflora, Z. verticillata, H.annuus,

Arctium minus, A. nemorasum, X, chinense, X« spinosum, X-

strumarium, Makania scandens, Hieracium alpinum, H.prenanthoides,

Inula:helenium, Carlina acoulis, Lactuca pernnis,Cosmos sp.,

Scorzonera hispenica and Felicia amelloides of the family

Compositae; Salpiglosis sinulata of Solanaceae and Cerianthe

major of Boraginaceae. Phlox isolate was restricted to

P. drummundi and cultivated perennial phlox. Cucurbit isolate

infected only members of Cucurbitaceae and failed to develop

on any non-cucurbit host included in the test. Schnathorst

et al. (1958) observed that Calendula isolate of E.cichoracearum

was pathogenic on Calendula officinalis and Silybum marianum,

while Lactuca sativa isolate was pathogenic on £, officinalis,

L. sativa, L, serriola, S. marianum and Z, elegans; L.serriola

isolate from Salinas and Z. elegans isolate caused infection

on L. serriola, _S. marrianum and Z, elegans, while L. serriola

isolate from Davis was pathogenic to L. serriola and

S, marianum. Therefore, the isolates of E. cichoracearum from

different localities from the same host different in their host

ranges.

Neger (1923) provided the evidence of cross infection

with conidia of _S. fuliginea from Epilobium montanum on

Taraxum officianle. Miller (1938) reported glasshouse infection

of Carica papaya seedlings with conidia of S, fuliginea in

64

California from cucurbits. Marcelli (1949) observed that in

cross-inoculations with conidia of S. fuliginea from Cucurbita

maxima onto squash, Cucumis anguria, C, melo, Citrullus vulgaris

and tobacco varieties resulted in the development of the mildew

except on tobacco varieties.

Huttenbach (1951) reported that inoculation with conidia

from potato on cucumber and vice versa resulted in infection.

According to Uozumi and Yoshii (1952) . fuliginea from Bidens

bipinnata was not pathogenic to cucumber but from Arctium lappa

was S. fuliginea, on the other hand, from cucumber was patho­

genic on A» lappa and Phaseolus radiatus but not on Solanum

melongena, Chrysanthemum coronarium, Helianthus tuberosus,

_H. annuus and Nicotiana tabacum. Nour (1959) observed that

conidia of _S. fuliginea obtained from the field samples of

Cucurbita pepo or Cucumis sativus were able to cause infection

on okra. Hibiscus esculentus. Similarly cross inoculations

from ti, esculentus onto £. pepo or _C. sativus were all success­

ful. Kowalski (1966) successfully inoculated _S. fuliginea from

Adonis vernalis to A, vernalis and Calendula officinalis but

not to Trollium europaeus. Alcorn (1968,1969) claimed that

cucumber isolates of _S. fuliginea was able to infect certain

plant species out side the family Cucurbitaceae. Cyamopsis

tetragonoloba, Dolichus unifloras, Phaseolus lathyroides,

P. vulgaris, Vigna vexiliata, H. esculentus, Verbena hybrida,

Carica papaya. Glycine javanica, _H. trionum, Physalis sp.,

Verbena bonariensis and Vigna lanceolata were infected with

conidia from cucumber and the above hosts were from the infected

65

cucumbers. Munjal and Kapoor (1973) also successfully inocu­

lated _S, fuliglnea from _C. pepo to Carica papaya and vice

vice versa,

Dorozkhin e_t al. (1978) observed that under Byelorussian

conditions Erysiphe cichoracearum f, sp. cucurbitacearum is

not narrowly specialized and can pass from wild plants to

cucurbits. Abiko (1983) studied the isolates of the pathogens

from tomato, which were pathogenic on tomato as i/vell as on

12 other species reported as hosts of E. cichoracearum.

Isolates from tobacco were pathogenic on tobacco, papaver

nudicaule and P. rhoes but not on 11 other species. Isolates

from 10 other species were host specific. He observed that the

curved conidiophores of E. cichoracearum on Plantago asiatica

and Galium spurlum var. echinospermum were easily distingui­

shable from the non-curved of E. cichoracearum on 10 other

species. The isolates were recognised as 12 specialised forms

on the basis of host range differences.

Host Races

Powdery mildews are highly specialized parasites of

plants. Existence of races with-incertain morphological

species of powdery mildews has been well established in some

species particularly in Erysiphe graminis (= Blumaria graminis).

Some attempts have been made to identify the races with in

powdery mildews of cucurbits specially in E. cichoracearum

and _S. fuliginea through their host specialization studies.

66

Alcorn (1969) reported the occurrence of four pathogenically

distinct races of _S. fuliginea on cucurbits in Queensland,

all of which infected Cucumis sativus, Cucurbita maxima and

_C, pepo, but not all infected the two cultivars of Cucumis

melo and the single cultivar of Citrullus lanatus var. caffer

onto which they were inoculated. Abiko (1978) reported five

distinct specialized forms of _S. fuliginea on cucubitaceous

and non-cucurbitaceous plants. He selected 5 isolates of

^» fuliginea from muskmelon, cucumber, winter squash and bottle

gourd and inoculated 19 host plants. He found that they were

all similar in their host ranges but different in virulence.

He noted that muskmelon, cucumber, winter squash, and bottle

gourd were easily infected but watermelon and white gourd

(Benincasa hispida) were not infected. These isolates also

infected sunflower, Cosmos bipinnatus. Zinnia sp. and Impatiens

balsamina. The fungus from watermelon had a similar host range

to that on muskmelon but was more virulent to watermelon than

the muskmelon isolate. Five distinct specialized forms of

^. fuliginea were recognized (1) on cucurbitaceae except

watermelon and white gourd (2) On watermelon (3) On eggplant,

(4) On arctium lappa (5) Pelasites japonicus. In India,

pathological specialization in Sj_ fuliginea was ruled out by

Akram and Khan (1977, 1978) while screening cultivated cucur­

bits to five isolates of _S. fuliginea collected from Jammu and

Kashmir and Uttar Pradesh.

Cross inoculation studies of I\lour (1959) between three

isolates of _S. fuliginea from various hosts were successful

67

which indicated the lack of pathological variability within

S, fuliginea. Kaur and Jhooty (1985) studied the pathological

specialization of six isolates of _S. fuliginea CHusing powdery

of cucurbits in Punjab. They noted three different patholo­

gical forms on the basis of^differential reaction of cucur-

bitaceous hosts. They surveyed the cucurbit growing areas of

Ropar, Hoshiarpur and Ludhiana in Punjab for the isolates of

_S. fuliginea. For testing the physiological forms, 3-4 leaf

stage seedlings of C. melo, jC. melo var, utilissimus, C. pepo,

Lagenaria siceraria, L. cylindrica and _C, lanatus were inoculated

by touch method (Jhooty and McKeen 1965) with different isolates

of _S. fuliginea. They noted that _C. pepo and L. siceraria were

infected by all the isolates, _C, melo was resistant to isolates

5 and 6 and moderately resistant to isolate 2. _C. melo var.

utilissimus, L. cylindrica and _C. lanatus were susceptible only

to their respective isolates i.e. isolate 5 and 6 and were

resistant to the isolates of 1,4. The above findings indicated

the presence of three distinct pathological forms of S.fuliginea

designated as form 1 on L. cylindrica, form 2 on C. lanatus and

form 3 C. melo, _C. melo var. utilissimus, _C. pepo and L.siceraria.

Thomas (1978) reported a new biological race of _S.

fuliginea in U.S.A. which was designated as race 3 while

studying the reaction of five cultivars of cantaloupe. His

study indicated that race 1, race 2 and race 3 are present in

U.S.A. There are also some records of occurrence of races of

E. cichoracearum on cucurbits. Two distinct races of

E. cichoracearum are known to exist in U.S.A. (Sitterly, 1978).

68

This differentiation was made while breeding powdery mildew

resistant cultivars of cucurbits by Jagger and Scott (1937)

and Jagger £t ^1^. (1938). At the time of these studies,

powdery mildew of cucurbits was recognized as E. cichoracearum.

But in view of recent report of widespread occurrence of

_S. fuliginea in U.S.A., the identity of the species selected

for race differentiation as E. cichoracearum seems to be

doubtful. It is possible that these differentiations were

done in _S. fullginea presuming it as E. cichoracearum.

Varietal Resistance

There are many reports in literature which indicate

that there are some varieties of cucurbits which are resistant

to powdery mildew (Jagger £t al., 1936; Tarr, 1952; Epps,1956;

Whitner, 1956; Tarnei £t al ., 1962; Smith, 1964; Rudich et al.,

1969). Some varieties have been reported resistant to

_S. fuliginea but susceptible to E, cichoracearum or vice-versa.

However, there are also some varieties which are resistant to

powdery mildew presumed as E. cichoracearum (Pryor _e_t al., 1946;

Bolm, 1958,1961; Bohn_et a],., 1965). Leppik (1966a) observed

that some lines with good resistance in the field showed less

resistance under glasshouse conditions.

Ballantyne (1975) prepared a list of cultivars and plant

introductions of C. melo, C. sativus, and Cucurbita species

which have shown resistance to powdery mildew in New South

Wales (Australia). In her screening of muskmelon cultivars,

Delta Gold, Edisto, PMR Nos. 6, 45 and 88, Rio Gold, Seminole

69

and U.S.P.I. Nos. 12411, 124112 and Subline L9p209 of 183310

showed no signs of mildew. Other cultivars (U.S.P.I. Nos.)

were affected severely at Rydalmere, New South Wales, in 1963.

In 1964 screening of cucumber cultivars, Pixie and Polaris were

resistant; Ashley, Polomar and Stono were moderately resistant;

U.S.P.I. 197087 gave a mixed reaction. Other cultivars and

U.S.P.I. Nos. were susceptible. The cultivars of _C. maxima,

_C. moschata, _C. pepo included in her screening at Rydalmere in

1964 were susceptible.

Akram and Khan (1978) made an attempt to search for

resistance to _S. fullginea in different cultivars of Benincasa

hispida, Citrullus vulgaris var. fistulosus, Cucumis melo,

£. melo var. momordica, C» melo var. utilissimus and Lagenaria

leucantha. They also tried to note whether _S. fuliginea

attacking different cultivated cucurbits in North India vary

in their pathogenecity. They found that all the varieties of

B.hispida viz. Khola petha^, Khola petha2 and Khola petha^

were moderately resistant to all the isolates in glasshouse

as well as in the field. Out of the five varieties of

C, vulgaris var. fistulosus viz. Dilpasand tinda.,, Dispasand

tinda2 and Lucknow special were susceptible the Tinda Delhi and

Gourd tinda were highly resistant in glasshouse against all

the isolates. All the varieties of C, melo became infected to

a varying degree with all the isolates. Delicious Faizabadi,

Kharra and Lucknow were highly susceptible; Jaunpuri, Lucknowp

Muskmelon2 Muskmelon^ and Muskmelon- were susceptible. Hearts

of gold was moderately resistant; Hales best improved and

70

Amritsari were resistant in glasshouse as well as in the

fields. Varieties of _C. melo var. momordica viz. Large,

Long and Phoot were highly susceptible; variety Small was

moderately resistant in glasshouse. However, in the field

all the varieties were highly susceptible. Varieties of

C. melo var, utilissimus, Hirvi., Hirvip. Jaunpuri , Jaunpuri„

were susceptible; Lucknow-, was resistant. Hot seasonp was

highly resistant. Varieties of L. leucantha viz. Lauki long^,

Lauki longp* Long white. Long thin, Lauki Singapuri and Lauki

round were highly susceptible; Doodhi long, White and Long

green were moderately resistant.

Angelov (1979) studied the susceptibility of 43 cucumber

cultivars to the _S, fuliginea. He noted that in some cases

fungal development and spore production were restricted; Line

22-a1, Aura, PI-22708-a and Cucumis anguria were highly

resistant while P.ointsett Summer prolific and PI-197088 and

197676 were resistant.

Angelov and Pethova (1979) noted that age of plants

plays a very important role in resistance of plants against

^. fuliRinea, They studied 25 specimens of cucumber and noted

that the degree of infection and the response at different

stages of plant growth varied. Plants at cotylednary stage

were highly susceptible to _S. fuliginea. Seedling and mature

plant were resistant.

Schlosser (1979) tested 75 cucumber cultivars against

E. cichoracearum and _S. fuliginea. He noted that 12 glasshouse

71

cultivars were highly susceptible to both pathogens. Of the

63 fields cultivars, 13 were resistant to E. cichoracearum but

susceptible to S, fuliginea and 8 were resistant to both.

Environmental Relationships

Infection in powdery mildews, by and large, is initiated

by conidia and rarely by ascorspores (Salmon, 1903; Steiner,

I9O8; Blodgett, 1913; Hammarlund, 1925; Cherewich, 1944;

Delmas, 1953; Power and Moseman, 1956; Schnathorst 1959) or

overwintering mycelium present in the dormant buds (Smith,

1894; Neger, 1915; Yossifovitch, 1923; 'ACoodward, 1927; Peterson

and Johnson, 1928,1944,1955; Yarwood, 1939; Dillon Weston

e_t al_., 1943; Yarwood, 1944,1957; Weinhold, I96I). Consequently

much of the work on biology of powdery mildews has been carried

out on the conidial stage.

Cucurbit powdery mildew is generally favoured by atmos­

pheric and soil moisture moderate temperature, reduced light

intensity, fertile soil and succulent plant growth (Yarwood,

1957). Out of the various environmental factors, temperature,

moisture (Delp, 1954; Yarwood, 1957; Schnathorst, 1965) and

soil fertility (Yarwood, 1949) appear to have a profound effect .

on the development of powdery mildews.

The relative importance of cucurbit powdery mildew in

different regions in U.S.A. is correlated with rainfall in

those areas. Powdery mildews, for example,may be very severe

72

in the summer in the arid portions of California, in Western

United States, but not very important in the eastern portion

of the United States where abundant rainfall normally occurs.

This may be true for other countries. Incidence of powdery

mildew thus increases as rainfall decreases. Spores may germi­

nate in the absence of water and in relative humidities below

20%, This fact implies that conidia have a high water content

and show an extremely efficient water conservation system.

Water is needed for germ.ination of conidia but it is internal

in vacuoles instead of requiring an external source (Yarwood,

1957). This process was confirmed by Duvdevani e_t al . (1946)

who prevented dew formation on cucurbits by covering certain

foliage areas with canvas, a procedure which did not reduce

powdery mildew infection.

ffeshioka (1937) studied the cardinal temperature for

the germinations of conidia of cucumber strain of _S. fuliginea

and observed that 15*, 23-31*C and 34"C were the minimal,

optimal and maximal temperature respectively. Tafradzhiiski

(1963), on the other hand, found 15-20°C as the optimal and

33-35®C as the maximal temperature ranges. Pfeshioka (1937)

observed that, the incubation period was 4, 3 and 7 days at

19.5 - 20.5 *C, 24« - 28"'C and 32*0 respectively. Optimum

temperature for infection of cucurbits was claimed at 28*C.

Moisture greatly influences the germination of conidia,

the infection and the development of powdery mildews. Hashioka

(1937) found that conidia of S. fuliginea germinated between

73

relative humidity 15-859 and that conidia survived for 14 days

at 76? to 80% relative humidity, 24 days at 93 to 98% and for

38 days in a saturated atmosphere, Tafradzhiiski (1963)

reported that conidia of _S. fulip:inea germinated best at

relative humidity 94% but they failed to germinate in drops

of water.

Reuveni and Rotem (1974) found that dry conditions

favoured fungal colonization, sporulation and dispersal while

high RH favoured fungal conidial survival. Chaudhari and

Siradhana (1975) observed the qualitative and quantitative

effect of light and temperature ranges on bottle gourd powdery

mildew. In their studies, they found that development of

^. fuliginea on L. ciceraria plants occurred maximumat 18-24°C

and 7 hours photoperiod.

Abiko and Kishi (1979) found the influence of tempera­

ture and humidity on the outbreak of cucumber powdery mildew.

Results indicated high humidity was most conducive to conidial

germination of _S. fuliginea.

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Peritheclal Formation In Powdery Mildews

of Cucurbits

Peritheclal of powdery mildews of cucurbits occur on

cucurbits frequently in some countries and rarely or not at

all in others (Ballantyne, 1975; Khan, 1977; Khan, 1983)

(Tables 9,10). The record of perithecia of E. cichoracearum

on Cucurbita pepo at Reigate in England by Salmon (1900) and

those by Humphries (1893) and Reed (1908) in U.S.A. were

earliest observations of peritheclal production by cucurbit

powdery mildew in nature. Since then, a number of reports

indicate the occurrence of perithecia either of E.cichoracearum

or _S. fuliginea or both on cucurbits in different countries«

Since the observations of E. cichoracearum perithecia

on cucurbits by Humphries (1893) and Reed (1908), the only

record of peritheclal observation of E. cichoracearum in U.S.A.

is that of Randal and Menzies (1956) who noticed them on

outdoor cucumbers. Recently, perithecia of . fuliginea

were observed by Kontaxis (1979) on squash. In U.3.S.R.,

there are several records of perithecia of both the species

on cucurbits (Deckenbach, 1924; Deckenbach and Koreneff,1927;

Rodigin, 1936; Teterevenikova-Babayan and Simonyan, 1956).

Deckenbach (1924) reported the perithecia of both the species

from Crimea. Deckenbach and Koreneff (1927) observed perithecia

oi" E« cichoracearum on upper surface and S. fuliginea on lower

surface of the leaves of C. melo in Crimea. Rodigin (1936)

observed the perithecia of both the species on cucurbits in

Volga basin. Teterevnikova-Babayan and Simonyan (1956) reported

81

perithecia of _S. fuliginea and E. cichoracearum in Armenia.

Rudenko (1968) found perjthecia of S. fulif inea and

E. cichoracearum on cucurbits in Moldavia. IDorozhkin and

Kapelyan (1975) found perithecia of _S. fuliginea and E.

cichoracearum on cucurbits in Bylorussia. Perithecia of

_S. fuliginea are reported from Astrakhan by Szembel (1926)

Poretzky (1923) reported perithecial production of cucurbit

powdery mildew in Caucasus.

Viennot-Bourgin (1956) recorded perithecia of E.

cichoracearuiTi in France; Roder (1937) and Schlosser (1972)

in Germany; and Marcelli (1949) in Italy. Nagy (1976) found

the perithecia of E. cichoracearum in Hungary. Junell (1967)

obtained the perithecia of E, cichoracearum in Sweden.

Perithecia of _S. fuliginea have been observed on several

cucurbits in different countries of Europe. Perithecia of

_S. fulipjinea were reported from Rumania as early as in 1929

(Savulescu, 1929). Nagy (1970) found perithecial production

of _S. fuliginea in Hungary; Fontidou (1971) in Greece; and

Blumer (1933) in Italy. Perithecia of _S. fuliginea have now

been recorded in The Netherland (Anon. 1965). Bremer et al.

(19^7) obtained perithecia of S. fuliginea in Turkey.

Perithecia of E. cichoracearum on cucurbits have not

been recorded in any country of Africa and South America and

Australia as it appears from different reports (Khan, 1983).

The perithecia of _S. fuliginea on cucurbit have been reported

from Sudan and Libya only in Africa (Tarr, 1955; Nour, 1959;

8 2

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84

El-Ammari and Khan, 1985) and from New Zealand (Dingley,1959;

Boesewinkel, 1976). There is no record of perithecia of S.

fullM.inea from North American and South American countries

except a solitary report by Kontaxis (1981) from U.S.A.

In Asian countries, Thompson (1933) has observed the

perithecia of E. cichoracearum on pumpkin in Malaysia and

Singapore. Rayss (19A7) and Palti (1962) recorded the

perithecia of S. fuliginea on cucurbits in Israel. Homma (1937)

and Sawada (1959) from Taiwan. Recently, Abul-Hayja and

Trabulsi (1981) reported the perithecia of _S. fuliginea from

Saudi Arabia.

In India, perithecial production in powdery mildews on

cucurbits have been reported from the States of Uttar Pradesh,

Bihar, Kashmir, Rajasthan, Madhya Pradesh and Kimachal Pradesh

(Tables 11,12). Bulter (1918), Khan _et £l. (1972), Malik et ^ .

(1973) and Sharma (1973) observed perithecia of E. cichoracearum

in Uttar Pradesh. Siradhana and Chaudhari (1972) and Malik

et al. (1973) reported the occurrence of perithecia of

E. cichoracearum in Rajasthan. Khosla et al_.(1974) and Dave

et al. (1971) observed perithecia of E.cichoracearum on

B. hispida and Trichosar^thes dioica in Madhya Pradesh. Butler

(1918) reported the occurrence of per'ithecia of E. cichoracearum

on _C. cordifolia and T. dioica at Pusa (Samastipur district)

in Bihar. Recently, Khan (1977) observed perithecia of

E, cichoracearum on _C. cordifolia at Sheikhpura (Fatna)

in Bihar.

85

Ferithecia of 3. fuliglnea have been reported from

Uttar Pradesh on L. leucan-cha, C. sativus and C. pepo (Butler

1918; Khan and Khan, 1970 and Sharna, 1973). Siradhana and

Chaudhari (1972) reported the occurrence of perithecia of _3.

fuliginea on L. leucantha from Rajasthan. Dave.et al. (1971)

recorded perithecia of . fuli^inea on L. leucantha and

Cucurbita maxima in Madhya Pradesh. Khan (1977) observed

perithecia of _S. fuliginea on L. leucantha at Sheikhpura (Fatna)

and Patna city area in Bihar. Butler (1918) and Khan et al.(l972)

observed perithecia of _S. fuliginea on _L, leucantha and

Cucurbita maxima in Kashmir and Sohi and Nayar (1969) on

_C. moschata in Himachal Pradesh.

There are also reports of perithecial production of

S, fuliginea in glasshouse conditions. Khan and Khan (1970)

noticed profuse development of perithecia of _S. fuliginea on a

number of cultivars of L. leucantha and C, sativus at Aligarh

(Uttar Pradesh) in the glasshouse. Khan e_t al. (1974) later

observed perithecial development of _S. fuliginea on certain

varieties of Citrullus vulgaris, Cucumis melo, C. sativus,

Cucurbita moschata. L. leucantha and Luffa cylindrica and those

of E. cichoracearum on certain varieties of B. hispida,

C. cordlfolia and C. melo in the glasshouse. _C. melo was found

as a host common to both species for perithecial production.

Khan (1978) proposed that in nature the most common host for

development of perithecia of E. cichoracearum is C. cordifolia

and for those of _S. fuliginea is L. leucantha.

86

The perithecial production is Erysiphyceae depends upon

atmospheric factors, heterothallism and nutritional status of

the host as suggested by Yarwood (1957) and Khan (1983). Khan

(1983) remarked that the reports of perithecial production in

nature from different regions emphasize the importance of

atmospheric factors particularly of temperature and relative

humidity. Biolexti (1907) reported that low temperature

favoured the development of perithecia. The role of temperature

on perithecial development of E, graminis was studied by

Cherwick (19^^) and Arya and Ghemawat (1953). They observed

that alternate low and moderate temperatures during the growth

of the plant favoured the development and maturation of

perithecia of E. graminis.

Buchheim (1928) and Blumer (19^8) reported that the

formation of perithecial of _S. pannosa occured only under low

moisture conditions. Schnathorst (1959) reported the formation

of functional perithecia of E. cichoracearum at 13''C, 60%

relative humidity and 900 ft. candles illumination and in

saturated atmospheric conditions at 23°C with 300 ft. candles

illuminations. Salmon (1903), Yossifovitch (1923) and Moseman

et al. (1957) reported that free water was essential for the

maturation of ascospores.

Khan and Khan (1970) observed, under glasshouse conditions,

perithecial production in _S. fuliginea after several days when

the fungus had fully established on the host. It required more

time during September and November (60-65 days) and less during

December to February (20-25 days). Khan (1983) believed that a

87

comple:xity of factors are involved in perithecjal production

and the set of environmental factors including host physiology

ensuring their production may vary among po dery mildew species

and their hosts.

Homma (1935) tested sexuality as a factor in perithecial

formation of 3. fuliginea. Although she reported homothallism

in _S. fuliginea but later she believed heterothallism as common

phenomenon in their production. Homma (1937) and Schnathorst

(1965) proposed that most Erysiphaceae are heterothallic. Both

mating types must be present in close proximity on the host

and environmental conditions must ensure their rapid development

and their mating.

Survival and Perpetuation

The mode of overwintering or oversummering oi cucurbit

powdery mildews and the role of perithecia and ascospores in

their survival and perpetuation are not yet well known in many

parts of the world. Perithecia are produced by a number of

Erysiphaceae. Perithecial production occurs in Sphaerotheca

pannosa on rose, _S. morsuvae on gooseberry, Unlnula necator on

grapes and Microsphaera alni in liliac, but their functional

role in perpetuation is not established. There are circum­

stantial evidences that they overwinter as mycelium in buds.

There are, however, certain reports of functional perithecia

and ascospores (Moseman and Powers, 1957; Schnathorst, 1959;

Yarwood, 1957). Yarwood (1957) and Schnathorst (1965) pointed

out that the formation of perithecia is no guarantee that they

function in nature.

88

In temperatt- clir .-te, powdery mildews are inactive

during winter and overAiinterin f, i. believed to be by means of

perithecia (Dash 19.53; 'A-r.vood, 1957); mycelium in the dormant

buds or as ordinary m:,'celium (Treboux, 1914), as chlamydospores

(Appel, 1903; Petri, 1924) or as active mycelium in warmer

regions. Overwintering as miyceliumi in dormant bud has been

reported for U. necator on grapes (Yossifovitch, 1923)>

Podosphaera leucotricha on apples (Yarwood, 1949). S. pannosa

on roses (Peterson and Johnson, 1928). The possibility of

overwintering or oversumm.ering as mycelium in buds incase of

powdery mildews of cucurbits is excluded because most of the

cultivated cucurbits on -vhich the disease regularly appears are

annuals (Khan, 1983). Jagger (1926) speculated that in view

of the rare perithecial production by E. cichoracearum on

cucumber,the fungus may be able to persist in vegetative form.

Yarwood (1957) pointed out that most acceptable manner of

overwintering of pov;dery mildew of cucurbits in U.S.A. may be

that they overwinter in the conidial state in Southern region

which is warm and blow North to each season. Rudenko (1968)

believed that the pathogens overwinter as perithecia as they

appear annually. In Australia, Alcorn (1967, 1969) found

seven non-cucurbit genera as alternative hosts of the cucurbit

powdery mildew and considered them possibly playing some role •

in prepetuation. Ballantyne (1975), however, ruled out this

possibility as these alternative hosts are subtropical and do

not survive winter conditions. She considered that conidia

are short-lived in winter conditions in Queensland ana southern

coastal New South ^ales in Australia and overwintering on some

89

other host may be the possible means of survival. In Englarui,

Stone (1962) demostrated that E. cichoracearum from cucumber

was able to overwinter on Sonchus asper and reinfects cucumuer

in the spring.

In the tropics as well as in the areas where the winter

is not very cold the povvdery mildew can overwinter as active

mycelium in sheltered situations, on a variety of volunteer

and cultivated cucurbits (Bessey, 194:5; Ainsworth and Bisby,

1950; rfoursi and Sirry, 1956; Jhooty, 1971). In Egypt, Moursi

and Sirry (1956) mentioned that E. cichoracearum attacks squash

throughout the year. In India, Jhooty (1971) reported that

some cucurbits like Luffa aegyptica, Lagenaria siceraria and

Citrullus colycinthis in sheltered places were capable of

maintaining powdery mildews of cucurbits caused by S.fuliginea

in its normal mycelium and conidial stage during the winter

months. Khan (1983) speculated that in the absence of any

experimental evidence of functional perithecia or maintenance

of any alternative host in vegetative forms, the possibilities

of oversummering of these pathogens on summer cucurbits on

hills and blowing each year to plains when the intense heat

and heavy rains are over and again to the hills during summer

may be possible means of survival of powdery mildews of cucurbits

in India.

MATERIALS AND METHODS

To achieve the objectives targeted in the plan of work,

some details of the materials and methods to be used and

experiments to be conducted are given below:

1, Survey and Collection

In order to establish the identity of powdery mildews

infecting cucurbit in different States, surveys will be con­

ducted in different States of the country. Through the surveys,

incidence and intensity of the disease on different cucurbits

in an area, or a region or State will also be determined. It

is proposed to include Uttar Pradesh, Bihar, Rajasthan, Madhya

Pradesh, Gujarat, Maharastra, Andhra Pradesh, Karnataka,

Tamilnadu, Kerala, Orissa, West Bengal and Andaman and Nicobar.

From some of these States (e.g. Uttar Pradesh, Bihar, Rajasthan

Madhya Pradesh, and Karnataka) some information with regard to

identity of powdery mildew, is available. But no information

in this regard is available from Gujarat, Maharashtra, Andhra

Pradesh, Tamil Nadu, Kerala, Orrisa, West Bengal and Andaman

and Nicobar island. In surveys, which will be conducted in

cucurbit growing seasons, available cucurbits will be examined

for the presence of the disease and recording of the symptoms.

The types of observations to be made during the surveys in

fields and in laboratory studies of field samples and record­

ing of the observations are given in the proforma I, After

the surveys and study of the samples, incidence of the disease

91

will be calculated for each area or a region or State by

using following formula.

, .^ Number of infected cultivation units Disease incidence m an area, a region or a State (Percentage) - Total number of Cultivation units " °°

surveyed.

To compare the disease incidence on different cucurbits

within an area, a region or in a State, incidence will be

calculated as given below:

Number of infected units of a given Disease incidence cucurbit in an area, a region or a (Percentage) _ State ^ xlOO

Total number of units of the cucur-bit surveyed

Intensity (disease severity) of powdery mildews on

different cucurbits grown in the area under survey will be

determined on 0-3 scale as given below:

No infection (0) = No visible disease symptoms

Mild infection (1) = Pustules few, small in size and scattered

Moderate infection (2) = Pustules many, large in size and tending to coalesce

Severe infection (3) = Big pustules, covering almost the entire leaf area

During the surveys infected plants will be closely

examined to study the symptoms present on various parts of the

plants and characteristics will be recorded. The representa­

tive samples which will include different aerial parts of the

plant selected at random from fields or cultivated units

(kitchen garden, farm yard, orchards etc.) will be collected

in polythene bags and properly labelled to indicate cucurbit

92

Pro forma I

Identity of Powdery Mildews of Cucurbits

Date

Surrey

Collection

Locality

Place . Town/Village

District State

Crop Age of the crop

No. of sample collected

Disease intensity

Symptoms __,_._____________._________,.. _.__________

General crop condition

Mycelium Ectophytic/Endophytic

Conidial shape

Germ tube morphology

Appressoria

Perithecia Present/Absent

Shape Colour

Perithecial measurements __,__________.^_____

Appendages

Ascospores/ascus Measurements of asci

Measurements of ascospores

Powdery mildews Sphaerotheca fuliginea/Erysiphe cichoracearum/

Leveillula taurica

Remarks

93

crop, location, date of collection etc. and brought to the

laboratory. Field samples will be studied macroscopically

and microscopically in the laboratory study.

2. Identity of Causal Organisms

The samples brought to the laboratory will be thoroughly

examined for presence of infection. Infected samples will

be closely examined for perfect stage with the help of dissect­

ing microscope and magnifying glass. Morphological characteris­

tics of the different structures of anamorph and teleomorph,

if present, will be studied microscopically and their dimensions

will be measured, Conidia will then be subjected to fibrosin

bodies test and germination test in order to study the absence

or presence of fibrosin bodies and the morphology of germ tubes

and appressorial development,

a. Fibrosin bodies test:

To test the presence of fibrosin bodies in conidia,

conidia from all the field samples will be'treated on clean

glass slides with 3% KOH aqueous solution. Conidia will be

then be examined under microscope (Kable and Ballantyne,1963)

and presence or absence of well-developed fibrosin bodies

will be noted. Percentage of conidia with fibrosin bodies

will then be calculated for each sample by random sampling of

conidia in a number of microscopic fields. By random exami­

nation of conidia with fibrosin bodies and counting their

number in each conidium,range and mean of number of fibrosin

bodies per conidium will also be determined.

94

b. Germination test;

Conidia from each sample will be subjected to germination

test in order to study the mode of germination and morphology

of germ tubes and development of appressoria. For the test,

conidia will be gently dusted on clean glass slides. At least

3 such slides from each sample will be then placed on glass-rod

triangles, kept in petriplates containing moistened cotton at

the bottom. The petriplates will be incubated at 20*C (^2).

At the end of the incubation period (24 h), slides will be

examined for observing the germination of conidia. The morpho­

logy of germ tubes will be studied and percentage germination

of conidia will be determined by random counting of germinating

and non-germinating conidia in a number of microscopic fields

from each slide. In samples wherever forking of some germ

tubes will be observed, percentages of conidia producing forked

and simple germ tubes will also be determinated. A set of

slides from each sample incubated in the same way as described

above will be examined after 48 h for detecting the develop­

ment of appressoria. The morphology of the appressoria will

be studied in each slide,

c. Host differential test;

Response of Lagenaria leucantha and Coccinia cordifolia,

the differential hosts for Sphaerotheca fuliginea and Erysiphe

cichoracearum will be studied by using potted plants or leaf

discs (Khan, 1978). Potted plants of host differentials will

be inoculated by dry dusting of conidia obtained from each

95

field samples separately. Pots of inoculated plants will be

kept at the glasshouse benches. Leaf-discs will be cut from

the fresh leaves of host differentials with the help of cork-

borer and floated on sterilized water surface contained in

petriplates. The upper surface of the leaf-discs will be

inoculated by dry dusting of conidia from the each of the

samples separately. The petriplates will be kept at 20*C (+ 2)

in an incubator and regularly examined for the appearance of

symptoms. In both, wherever symptoms of the disease will

appear and growth of the pathogen will occur on inoculated

leaves or leaf discs, the conidial characters will be studied.

The characters of the pathogen will be then matched with those

observed in the original field sample. Variations in the

response of the host differentials to different collections,

if any, will be noted.

When assessment of the Incidence and intensity of the

disease, identification of the causal species are over, a

distribution map of different species of powdery mildews

encountered in each State depicting their incidence, intensity

and relative dominance will be prepared. Similarly, a map

to show the incidence and intensity of the disease on different

cucurbits caused by each species in each State will also be

prepared.

3. Culturlng and Maintenance of the Pathogen

For experimental studies in glasshouse conditions,

inocula from selected samples considered necessary, preferably

from areas of high disease intensities of different States,

96

will be maintained in glasshouse on young plants of cucumber

grown in pots containing autoclaved soil. Plants of L.leucantha

for S, fuliginea and C. cordifolia for E. cichoracearum will

also be used for maintenance whenever required. Inoculations

will be done by dry dusting of conidia or appressing infected

areas of the leaves on the surface of leaves of the seedlings.

Subsequent inoculations when found necessary will be done to

maintain the inocula for desired periods.

4, Host Range Studies

For host range studies, cultivated and some wild

cucurbits and non-cucurbits grown in 25 cm. five replicate

clay pots containing autoclaved soil (sand:field soil:farm

yard manure 1:2:1) will be inoculated with isolates of powdery

mildews obtained from different States and maintained in the

glasshouse. Inoculated plants will be kept at the glasshouse

benches. Plants will be regularly examined for the appearance

of the disease till 20th day after inoculations after which

plants will be classified as host and non-host accordingly.

5. Screening of Cultivars

Commercially grown popular as well as newly introduced

cultivars of more commonly grown cucurbits viz., bottle gourd,

pumpkin, sponge gourd, cucumber, longmelon, muskmelon and

watermelon will be screened in artificial inoculations in the

glasshouse using potted plants as well as on leaf discs in

the laboratory. For screening, isolates of S. fuliginea.

97

E. clchoracearum and L. taurlca (if available) will be used in

inoculations. 3-4-leaf-stage seedlings grovm from surface

sterilized seeds in autoclaved soil (sand:field soil:farm yard

manure 1:2:1) will be inoculated by dry dusting of conidia

onto leaves. The screening of cultivars in the pots will

also be supplemented with artificial inoculations of leaf

discs in petriplates (Morrison,1964). Leaf discs of each of

the cultivars of cucurbits included in the screening will be

inoculated by dry dusting of conidia onto the surface of float­

ing leaf discs in sterilized water contained in petriplates.

Inoculated seedlings as well leaf discs will be observed

regularly daily for two weeks. Whenever, the development of

the disease will be noticed, the following numerical rating

for disease intensity will be used.

Description

Plants completely free from

infection

Mycelium developing in small

patches disappearing later or

at best covering 1-2596 leaf

area

Mycelium developing both on

leaves and stem covering

26-5096 leaf area

Many small colonies appearing,

later coalescing and covering

51-7596 leaf and stem area

Entire plant covered uniformly

by mildew.

Infection rating

Grade

Highly resistant

Resistant

Moderately resistant

Susceptible

Highly susceptible

98

Throughout the screening of the cultivars petrithecial

production will be also examined. When produced, the time

for the appearance of perithecia will also be recorded. Later

the perithecia will be ruptured and examined for asci and

ascospores,

6. Consistency in Conidial Characters

To ascertain the consistency in conidial characters like

shape and dimensions, presence and absence of fibrosin bodies

and morphological characters of germ tubes particularly in

S. fuliginea and E, cichoracearum, following experiments will

be conducted:

6.1 Effect of culturing;

The effect of culturing on the conidial characters

(shape and dimensions, development of fibrosin bodies, mor­

phology of germ tube) of , fuliginea and E. cichoracearum

will be studies under glasshouse conditions in two ways.

a. Continuous culturing on the same host;

Prior to inoculations in the experiment, conidial

characters of the pathogens to be used in inoculation will

be studied and recorded. Then the pathogens will be inocula­

ted and cultured continuously on the same host under glass­

house conditions for a prolonged period of time (5-6 months)

on the same host with regular transfers on fresh plants at

monthly intervals. At the time of each transfer (inoculation)

the conidial characters (as enumerated above) will be examined

99

and observations will be recorded. In this experiment,

S, fuliginea and E. cichoracearum will be included and

variations, if any, will be noted. S, fuliginea will be

cultured on L. leucantha and Cucumis sativus and E.

cichoracearum on C. cordifolia and C, sativus.

b. Culturing on different cucurbits;

In order to ascertain the effect of host on conidial

characters of . fuliginea and E. cichoracearum, artificial

inoculations of different cucurbits (depending upon their

host range) will be made from the same inoculum source of

each species under glasshouse conditions. The cucurbits to

be inoculated within the host range of each species will

include most congenial, modertate and least preferred hosts.

When the conidial stage has developed on the cucurbits,

conidial characters as given above will be examined and obser­

vations will be recorded and variations, if any, due to host

effect will be noted.

6,2 Effect of certain ecological factors;

Effect of two atmospheric factors-temperature and

relative humidity-on conidial characters of S, fuliginea and

E, cichoracearum will be studied in artificial inoculations

employing leaf disc method. Circular leaf discs (1 cm diam.)

of different cucurbits cut out by sharp cork borer will be

floated on sterilized distilled water contained in sterilized

petriplates. The leaf disc will be inoculated by dry trans­

ferring of conidia onto upper surface of the leaf discs. Each

100

treatment will be replicated five times. Petriplates contain­

ing inoculated leaf discs will be inocubated at varying

temperatures in incubators (5*C, 10'C, 15*C, 25*C, 30"C and

35*C). The effect of various levels of relative humidity

will also be studies by using leaf disc method as described

for temperature. The various levels of humidity will be

created artificially by using sulphuric acid solutions of

different gravity (Buxton and Mellenby, 1934). In both experi­

ments, when the conidial stage has developed on inoculated

leaf discs, observations on the-conidial characters will be

made and recorded and variations if observed, will be noted.

6.3 Effect of nutritional status;

Cucumber, a common host for both the pathogens, will be

grown in thoroughly washed and sterilized sand contained in

glazed ceramic or plastic pots. Different levels of NPK (i N-

i of the normal dose, N-normal dose, 2N-double of the normal

dose) will be added to the pots. Seedlings grown in different

treatments will be inoculated with S^, fuliglnea. After the

appearance of the disease and development of conidia on

inoculated seedlings, conidial characters will be examined and

observations will be record^d^ A similar experiment will be

conducted for E, cichoracearum.

7. Effect of Nutritional Status and Age on the Consistency of the Differential Hosts

C, cordifolia (the differential host infected by

E. cichoracearum) and L- leucantha (differential host infected

by S. fullginea) will be grown in sand culture in glazed

101

ceramic pots or plastic pots to be supplied with different

levels of NPK ( N, N, 2N). In one set, seedlings of both

C» cordifolia and L. leucantha will be inoculated with

^. fuliginea. In another set, seedlings of both the plants

will be inoculated with E. cichoracearum. The inoculated

seedlings of both the sets will be kept separately in the

glasshouse chambers. The seedlings will periodically examined

for the appearance of the disease. After fifteen days of

inoculations, observations will be recorded. Whenever symptoms

will be found, the pathogen will be identified on the basis of

conidial characters. Any variation in this response will be

recorded.

To test the effect of age on the consistency of

differential hosts, C. cordifolia and L, leucantha plants of

different ages (from seedling stage upto mature plants) will

be inoculated with both _S. fuliginea and E. cichoracearum in

separate sets and will be kept separately in the glasshouse

for observation of the development of symptoms. Plants

showing symptoms will be examined and the pathogen involved

in the disease will be identified as described earlier.

8. Race Differentiation

Since there are no standard host differentials for

differentiation of races in powdery mildew of cucurbits,

methods are to be devised and standardized in order to attempt

such differentiation. In the present study, differentiation

of races in S, fuliginea will be attempted through two

different ways-

102

1, Cross inoculation

2, Response of host differentials

1, Cross inoculation - From my preliminary observations as

well as from literature it is evident that some cucurbits

(e.g. L. leucantha, jC. sativus and C, melo var. utilissimus)

are heavily infected with S, fuliginea; some cucurbits

(e.g. L. cylindrica, B, hispida) are less commonly infected

while a few (e.g. C, vulgaris) usually reamin free from

, infection. Thus they can be differentiated into three arbi­

trary categories.

I- Commonly infected cucurbits.

II- Less commonly infected cucurbits.

III- Rarely infected cucurbits.

For inoculation experiments as attempted by Kaur and

Jhooty (1986), various cucurbits growing areas of the country

as given in survey programme will be surveyed and isolated

from three groups of cucurbits (I,II,III) as mentioned above

will be collected and maintained on respective hosts in the

glasshouse chambers separately. Cross inoculation will be

made from isolates of three different cucurbits and will be

inoculated according to following scheme-

Cross inoculation scheme

1. Isolates from I category of cucurbits

I category inoculation II category of cucurbits

of cucurbits III category of cucurbits

103

2, Isolates from

II category

of cucurbits

inoculation

I category of cucurbits

II category of cucurbits

III category of cucurbits

3. Isolates from

III category

of cucurbits

inoculation

I category of cucurbits

II category of cucurbits

III category of cucurbits

Infection, disease development and intensity will be observed

after 10 days of inoculations. Results of inoculations may

give an idea of pathogenic specialization. If indication for

pathogenic specialization will be found, it will be confirmed

by repeating the experiment. Variation in pathogenic specia­

lization may help in differentiation of races in . fuliginea.

2, Response of Host differentials - Khan (1978) proposed

L. leucantha and C. cordifolia as differential hosts for

differentiating _S. fuliginea from F, cichoracearum. It is

generally found that L, leucantha is infected by _S. fuliginea

but not by E. cichoracearum and C. cordifolia is infected by

E. cichoracearum and not by _S. fuliginea. For race differen­

tiation in S. fuliginea these two host differentials will be

used for inoculation with different collections of S, fuliginea

with a view of possibility that some of the isolate (s) of

S, fuliginea may infect C, cordifolia. This study will be

carried by using potted plants or leaf discs. Potted plants

of host differentials will be inoculated by dry dusting of

conidia obtained from each field samples separately. Pots of

inoculated plants will be kept in the glasshouse chambers.

104

In both, wherever symptoms of the disease will appear and

growth of the pathogen will occur on inoculated leaves or

leaf discs, the conidial characters will be studied. The

characters of the pathogen will be then matched with those

observed in the original field samples. Variations in the

response of the host differentials to different collections,

if any, will be noted. This may provide clue for existence

of races.

LITERATURE CITED

Abiko, K. 1978. Studies on the specialization of parasitism

of Sphaerotheca fuliginea (Schlect) Pollacci I. Powdery

mildew fungi parasitic on cucurbits, eggplant, edible

burdocle and Japanese butter bur. Annals of the

Phytopathological society of Japan. 44(5): 612-618.

Abiko, K, 1983. Studies on the specialization of parasitism

in Erysiphae cichoracearum. Bulletin of the vegetable

and ornamental crops. Research station No.11: 119-126.

Abiko, K, and K, Kishi. 1979. Influence of temperature and

humidity on the out break of cucumber powdery mildew.

Bulletin of the vegetable and ornamental crops research

station 5: 167-176.

Abul-Hayja, Z.M. and I.Y. Trabulsi. 1981. Sphaerotheca

fuliginea on cucurbits in Saudi Arabia. Trans. Br.

Mycol. Soc. 76: 506-507.

Ainsworth, G.C. and G.R. Bisby. 1950. A dictionary of the

fungi 477 pp. Commonwealth Mvcological Institute.

Kew, Surrey, England.

Akhundov, T.M. and U.L. Yanishchev, V.I. 1963. Disease of

ornamental plants in Aspheron (IZV. Akad. Nauk. Azerb

S.S.R.) Ser. biol. Smed. Sci., 1963(2): 13-19, 1963

(Azeri Summery)(Rev. Appl. Mycol. 43: 360, 1964.)

106

Akram, M,, A.M.Khan and A.Khan. 1975. Host-range studies

of Sphaerotheca fuliginea. Indian Phytopath. 28:

483-485.

Akram, M. and A.M.Khan. 1978. Studies on the cucurbit powdery

mildew.III. Varietal response of some cultivated cucur­

bits to Sphaerotheca fUliginea. Indian Phytopath.31;

93-94.

Alcorn, J.L. 1968. Cucurbit powdery mildew on pawpaw. Old.

J. Agric. and An. Sci. 25 (3): 161-164. (Rev. APPI.

Mycol. 48: 52, 1968).

Alcorn, J.L. 1969. Infection experiment with cucurbit powdery

mildew. Aust. J. Sci. 31(1): 296-297.

Alexandreff, L.A. 1927. Tobacco mildew Qidium tabacci (Thum).

on southern coast of Crimea in 1926. (Material for

Mycol and Phytopath.). Leningrad, 6: 58-66.

Allison, C.C. 1931. Powdery mildew of Flax in Minnesota.

Phytopathology 24: 305-307.

Allison, J.L. 1952. Diseases of economic plants in Iraq.

FAQ PI. Prot. Bull. 1: 9-11 (Rev. Appl. Mycol. 32:

473, 1953).

Angelov, D. 1979. Study of the susceptibility of cucuunber

cultivars to the pathogen of powdery mildew (Sphaerotheca

fuliginea. Poll.)- Gradinarska i Lozarska Nauka. 16:

98-108.

107

Angelov, D. and T. Pethcl'va. 1979. Age resistance of cucumber

to the pathogen oft powdery mildew (Sphaerotheca

fuliginea. Poll.) Glradinarska i Lozarska Nauka. 16:

93-97.

Anonymous 1950. Plant ditseases, Agric. Gaz. N.S.W. 61: 517-521.

(Rev. Appl. Mycol.f 30: 310).

Anonymous 1950. Report i of explanatory investigations of

agricultural probllems of Alaska. Misc. Pub. U.S. Pep.

Agric. 700, 185 ip. (Rev. Appl. Mycol. 29: 498, 1950)

Anonymous 1961. Annuall report. Department of Agriculture,

Kenya (Rev. Appll. Mycol. 42: 297, 1963).

Anonymous 1965. Institsute of Horticulture plant Breeding.

Annual report fori 1964. Wageningen. Medeling. 240,

60 pp.

Anonymous 1967. Report/s of the second seassion of the near

east plant protey^tion commission, Tripoli Libya.

(Rev. Appl. Mycpl. 48: 67, 1969). f •

Anonymous 1969. Hap.d Book of Agriculture, I.C.A.R.. New

Delhi.

Anonymous 1975. Taxon. 24: 553-554.

108

Appel, 0, 1903. Zur kenntnis-der uber winterung des (Oldium

tuckeri) Centralbl. Bakt. (2nd Abt) 11: 143-145.

Arya, H.C. and M.S. Ghemawat. 1953. Occurrence of powdery

mildew of wheat in the neighbourhood of Jodhpur. Indian

Phytopath. 6: 123-130.

Badayeva, P.K. 1930. Flax diseases in Siberia. Preliminary

data. Morbi Plantarum, Leningrad. 19(3-4): 192-199.

(Rev. Appl. Mycol. 10: 459, 1931).

Bailey, L.H. 1929. Domesticated cucurbits. Gentes Herbarum,

II, Fasc. II, 63-115, Ithaca, New York.

Baimuratora (Mme) G. 1961, Data on the parasitic fungus flora

of the Gblodnaya steppe. Uzbek Biol. 3: 8-15 (Rev. Appl.

Mycol. 41, 18, 1962).

Baker, K.F. 1943. Sphaerotheca humuli var. fuliginea on

Delphinium in California. Phytopathology 33: 832-834.

Ballant3nie, B.J. 1963. A preliminary note on the identity

of cucurbit powdery mildews. Aust. J. Sci. 25: 360-361.

Ballantyne, B.J. 1975. Powdery mildew of cucurbitaceae:

Identity, distribution, host range and sources of

resistance, Proc. Linn. Soc. New South Wales 99: 100-120,

Banga, 0. 1956. International conference on the improvement

of vegetable varieties at Wageningen Netherlands on

August 26 and 27, 1955. Euphytica 5: 18-32 (Rev. Appl.

Mycol. 35, 649, 1956).

109

Barratt, R.W. 1942, Occurrence of tomato leaf mold & of

muslmelon powdery mildew in the field in New Hampshere

PI. Dis. Reptr. 26: 49.

Beeley, F, 1932. Effect of meteorological factors on the

virulence of Oidium hevae in Malaya. Jour. Rubber Res.

Inst. Malaya. 4: 104-114.

Bell, E.H. and S. Alandia 1957. Diseases of temperatre climate

crops in Bolivia. PI. Dis. Reptr. 41: 646-649.

Bessey, E.A. 1943. Notes on Ifewaiiam fungi. Papers Mich.

Arts Letters. 28: 3-8,

Benada, J, 1974. The susceptibility and resistence of

cucumber and squash tissues to powdery mildew

Sphaerotheca fuliginea in relation to oxidation reduc­

tion potential and pH. Ceska Mycologie. 28: 44-53

(Rev. K-. Path. 53: 654, 1974),

Bioletti, F.T. 1907. Oidium or powdery mildew of the vine.

Calif. Agr. Exp. Sta. Bull. 186: 315-350.

Blackford, F.W. 1943. Downy mildew and powdery mildew of

cucumber. M.. Agric, J. 7: 164-165.

Blasquez, C.H. 1970, Varietal resistance to three cucumber.

At foliar diseases in South-west Florida, PI. Dis.

Reptr, 54: 52-55,

Blodgett, F.M, 1913, Hop mildew, Cornell Univ. Agr. Exp. Sta.

Bull. 328: 281-310.

110

Blodgett, F.M, 1915. Further studies on the spread and control

of the hop mildew. N.Y. (Geneva) Agr. C£. Sta. Bull.

395: 29-80.

Blumer, S. 1922. Das problem der "Bridging species" bei den

parasitic hen Pilze. Mitt.Naturf. Ges. Bern 1922.

XLV - XLVI

Blumer, S. 1933. Die Erysiphaceen Mitteleuropas mit besonder-

er Beruckichtigung der Schweiz. Beitr. Kryptogamenf1 ora

der Schweiz 7: 1-483.

Blumer, S. 1948. Beitrage Zur Kenntnis der Erysiphacean,

Ber schweiz, Bot. Gesellsch. 58: 61-68 (Rev. Appl.Mycol.

28, 360, 1949).

Blumer, S. 1951. Beitrage zur kenntris der Erysiphacean

Mitteilung (Contribution to the knowledge of Erysipha-

ceae) Note-2. Phytopathology 2: 101-110 (Rev. Appl.

Mycol. 31, 148, 1952).

Blumer, S. I960. Echter Medtau auf Susskirschan (Prunus avium

L.) und Zwetschgen (Prunus domestica L.) Phytopath. Z.

37: 317-320 (Rev. Appl. Mycol. 39: 476).

Blumer, S. 1967. Echte Mehltaupilze (Erysiphaceae) Veb.

Gustav. Fischer Verlag, Jena.

Boerema, G.H. and H.A. Van Kesteran. 1964, De identiteit von

de echte meeldauw bij cucurbitaceae. Neth. J. Plant

Pathol. 70: 33-34 (Rev. Appl. Mycol. 43: 449, 1964).

111

Boesewinkel, H.J. 1976. Cleistothecia of powdery mildews in

New Zealand. Trans. Br. My col. Soc 67: 143-146 (Rev.

PI. Path. 56: 303, 1977).

Bohn, G.W. 1958. Out look bright for control of crown blight

in muskmelon. Western Grower and Shipper, 29: 94-95.

Bohn, G.W. 1961. Inheritance and origin of nectarless musk­

melon - a yield reducing mutant character. J. Hered. ,

52: 233-237.

Bohn, G.W. 1964. Genetics of resistance to powdery mildew

race 2 in muskmelon. Phytopathology. 54: 587-591.

Bohn, G.W. and T.W. Whitaker. 196I. A new host for the

cucurbit powdery mildew fungus. £1. Pis. Reptr. 45:

232-234.

Bphn, G.W., G.N. Davis, R.E. Poster and T.W. Whi taker. 1965.

Campo and Jacumba, new cantaloupe varieties for the

South Wales. Calf. Agric. 19: 8-10.

Boughey, A.A. 1949. The ecology of fungi cause economic

plant diseases. Trans.Br. Mycol. Soc. 32: 179-189.

Bouwens, H. 1924. Untersuchungen uber Erysipheen. Meded.

Phytopath. Lab. Willie, Commelin Schotten. Baarn 8:

1-47.

Bouwens, H. 1927. Weitere untersuchungen uber Erysipheen.

Meded.Phytopath. Lab. Willie, Commelin Schoiten. Baarn

10: 3-31 (Rev. Appl. Mycol.. 6: 511-512).

112

Boyd, O.C. 1928. Powdery mildew caused by Eryslphe

clchoracearum DC. U.S. Dep. Agric. Bur. Plant Indus.

PI. Dis. Reptr., Sup. 68: 75, 1929 (Mimeographed)

Bradbury, J.F. and R.W. Fisher. 1963. Control of powdery

mildew of cucumbers with polybutene emulsions. PI.

Dis. Reptr. 47: 1062-1064.

Bremer, A. 1940. Beobachtungen quantitativer Art uber das

Auftreten von Schaden an auf dem versuch.sfelte der

Zweig stelle Ascherleben Gemusepflazen der Biologische

Reichsanstalt fur Landund Forstwirts Chaft Wahrend der

Jahre 1929 bis 1935, 3: Mitteil: Pflanzenkrankh. 50,

577-595.

Bremer, H., H. Isme, G. Karel and H. Ozkhan. 1947. Beitrage

zur kenntnis der parasitischen pilze der Turkei.I. Rev.

Fac. Sci. Univ. Istanbul Serie, B, 12: 122-127.

Brisley, H.R. 1926. Recent information concerning powdery

mildew in Northern Arizona. PI. Dis. Reptr. 10: 104.

Brundza, K. 1933. Beitrage Zur Kenntnis-der Erysiphaceen

Litauens. Jahrb. Land Wirts chaft. Akad. Litauen. 1933:

108-197.

Buchheim, A. 1928, Biologische morphologische unter such

urgen an Erysiphaceen. Ber. Dent. Bot. Gest. 46: 167-180,

Buchwald, N.F. 1936. Plante pathologiske Meddeteser.1-5.

(Phytopathological notes 1-5) K. Vet. Hojsk Aarsskr.

1936 pp. 132-140. 1936 (English summary)(Rev. Appl.

Mycol. 16: 63, 1937).

113

Butler, E.J, 1918. Fungi and disease in plants. Thacker and

Spink and Co. Calcutta.

Buxton, P.A. and K. Mellenby. 193^. The measurements of

humidity. Bull. Ent. Res. 25: 171-175.

Bychenko, N.I. 1971. Effectiveness of different fungicides

against powdery mildew of cucumber grown in glasshouses.

Khlmlya sel, Khoz 9: 29-31. (Rev. PI. Path. 51, 178,1972).

Cannon, O.S. 1962. Powdery mildew of potato in Utah. Proc.

Utah Acad. Sci. 39: 188. (Rev. Appl. Mycol. 42: 401,

1963).

Chakravarty, H.L. 1959. Monograph on Indian cucurbitaceae

Taxonomy and distribution. Records of the Botanical

survey of India 17(1): Vol. XVII.

Chaudhari, G.R^ and B.S. Siradhana. 1976. Qualitative and

quantitative effect of light and temperature reanges on

bottle-gourd powdery mildew. Indian J. Mycol. PI. Path.

6: 201-202.

Cherewick, W.J. 1944. Studies on the biology of Erysiphe

graminis DC. Canad. J. §ss, C. 22: 52-86.

Cheremisinov, N.A. 1951. Mildew of Kok-saghyz. J. Bot.

U.S.S.R. 36, I. pp. 72-77, 2 figs. (Rev. Appl. Mycol.

31: 31, 1952).

114

Chin, W.F., S.S. Liang and C.S. Hwag. 1959. Field trials of

controlling the cucumber mildews. Acta Phytopath. Sinica

5: 123-131 (Rev. Appl. Mycol. 528, 1960).

Clare, B.G. 1958. The identity of cucublt powdery mildew

of South-Eastern Queensland. Aust. J. Sci. 20: 273-274.

(Rev. Appl. Mycol. 38: 556, 1959).

Clare, B.G. 1964. Erysiphaceae of South Eastern Queensland.

University Queensland Papers IV (10): 111-114.

Clark, R.L. 1975. Powdery mildew resistence in plant intro­

ductions of cucumber in Iowa. PI. Pis. Reptr. 59:

1024-1028.

Clarke, C.B. 1879. Cucurbitaceae in Hooker's flora of

British India, 11: 604-635, London,

Conover, R.A. 1957. Phytotoxicity of fungicides to canta­

loupes.Pro£. Fla. HOrt. Soc. 69: 198-200 (Rev. Appl.

Mycol. 632, 1957).

Corner, E.J.H. 1935. Observations on resistance to powdery

mildew. New Phytol. 34: 180-200.

Corner, I.L. 1956. Thirty fifth annual report of the

Canadian. Plant disease survey, 1955. 21: 130.

Cruger, G. and E. Meyer. 1976. Possibilities to differentiate

the powdery mildew agents (Sphaerotheca fuliginea and

E. cichoracearum') on cucurbits; Nach. des Deutschen

Pflanzenschutzdienstes. 28: 49-55.

115

Dash, J.S. 1933« The powdery mildews. Ann. Rep. Quebec Soc.

Prot. PI. 5: 32-38.

Dave, G.S., H.K. Khosla and K,G. Nema. 1971. Identity of

powdery mildews of cucurbits-I. J.N.K.V.V. Res. J. 5:

133. (Rev. H,. Path. 5: ^32, 1972).

D'Angremond, A. 1924. De Veldschimmel (Oidium sp.) in de

vorstenlanden, Proefstat vorsten landensche Tabak,

Meded 52: 7-25 (Rev. Appl. Mycol. k: 130-131, 1925).

De Candolle, A.P. 1882. Origin of cultivated plants. Hafner

Putu Co. New York. 1950.

De Carvalho, T. 1948, Preliminary reports on the diseases

observed in plants and isencts with phytopathological

annotations. Colonia de Mecambique Reptricao de

Agricultura, Seccaco de Micologia,1948.64 pp (Rev..Appl.

Mycol. 29: 89, 1950).

Deckenbach, K.N, 1924. On mildew fungi parasitizing cucur-

bitaceae and tobacco on the south coast of crimea.

Morbi. Plantarum Leningrad. 8: 98-102 (Rev. Appl.

Mycol. 5: 70-71).

Deckenbach, K.N. and M.S, Koreneff. 1927. Contribution to

the study of the mildew fungi of plantation crops in

Crimea. Morbi. Plantarum Leningrad. 16(2): 155-160.

(Rev. Appl. Mycol. 7: 273).

Dekker, J. 1961. Systematic activity of Procaine hydrochloride

on powdery mildew. Tijdschr. Plziekt. 67; 25-27 (Rev.

Appl. Mycol, 40: 515, 1961).

116

Dekker, J. 1963. Effect of kinetin on powdery mildews.

Nature, Lond. 197, 1027-1028.

Delmas, H.G. 1953« L'Oidium' de L'Abrlcotier en Roussilon,

Ann. Int. Reoh. agron. Ser. (Ann. des. Epiphyt.) 4:

59-89.

Delp, G.J. 1954. Effect of temperature and humidity on

the goape powdery mildew fungus. Phytopathology 44: 615-D26,

Deslandes, J.A. 1954. Studies and observations on lettuce

powdery mildew. PI. Pis. Reptr. 38: 560-562.

Devarennes, E.M., A. Amarilis, De Marta Sequeira and P.Das.

1964. Estac. agron nac Sacarem. Erysiphaceae lusitaniae.

1- Agron lusit. 24(2): 87-131, 1962. (1964) (Rev. Appl.

Mycol. 43: 410, 1964).

Dillon Weston, W.A.R. and E. Taylor. 1943. Some observations

on powdery mildews. Trans. Br. Mycol. Soc. 27: 119-120.

Dingley, J.M. 1959. New records of fungus diseases in New

Zealand. N.Z,J.Agric. Res. 2: 380-386 (Rev. Appl. Mycol.38;

674, 1959).

Dingley, J.M. I960. New records of fungus diseases in New

Zealand. 1958-59. N.Z.J.Agric.Res. 3: 461-467. (Rev.

Appl. Mycol. 40: 88, 1961).

Dingley, J.M. and R.M. Brien. 1956, New records of fungus

diseases in New Zealand. 1955-56, W.Z.J.Scl. 38(4):

434-439. (Rev. Appl. Mycol. 36: 426, 1957).

117

Dixon, G.R. 1978. Powdery mildev* of Vegetable and allied

crops, pp. A95-524 in D«M. Spencer, ed. "The Powdery

Mildews". Academic Press, London, New York. San

Francisco.

Docea, E, and E. Fratila. 1980. A new pathogen causing

powdery mildew of cucumber in Romania. Lucrayi Stuntifice

22: 165-168 (Rev. PI. Path. 60: 563, 1981).

Document, V. 1921. Oidium de La Pomme derre et Oidium de la

Betterance Bull. Soc. de Path. Veg. de France. 8:

153-154. (Rev. Appl. Mycol. 1: 361, 1922).

Dorozhkin, N.A. and M.F. Kapel'yan. 1975. Specific composi­

tion and some questions of the biology of the pathogens

of powdery mildew of cucumber under conditions of

Byelorussia. Ovoshchevodstvo No.3: 60-63.(Rev. PI.Path.

4354, 1976).

Du Toit, J.J. 1948. Powdery mildew or white rust on cucurbits

Fmg. S. Afr. 23: 273, 815-816.

Duvdevani, S., S. Reichert and J, Palti. 1946. The development

of downy and powdery mildew of cucumbers to dew and

other environmental factors. Palestine J, Botany 5:

127-151.

Eastern, J.W. and M.H. Ruhman. 1924. Diseases and pests of

cultivated plants. Brit. Cal. Dept. Agric. Bull. 68 p.

112.

116

El-Amaiani, S.S. 1983« Studies on certain aspects of powdery

mildews of cucurbits in Libya. M.Sc. Thesis Faculty

of Agriculture Alfateh Univ., Tripoli.

El-Ammari, S.S. and M.W-Khan. 1983. Leveillula taurica

powdery mildew on greenhouse cucumbers in Libya.

Plant Disease 67: 553-555.

El-Ammari, S.S., M.W.Khan. 1985. Libyan Arab Jamahiriya:

Sphaerotheca fuliginea (perithecial stage) on cucurbits.

I M £i' Prot. Bull. 33: 42-43.

El-Kazzaz, M.K. 1983. Sphaertheca fuliginea (Schlet exFr.)

Poll, the causal agent of powdery mildew on many of

the cucurbits in Egypt. Etyptian J. Phytopathol. 13:

65-66.

Elenkov, E., I. Tafradzhiiski and G. Neshev. 1975. A new

pathogen of powdery mildew of cucumber in Bulgaria.

Rastit. Zasht. 23: 36-38 (Rev. PI. Path. 55: 88, 1976).

EHade,E. I960. Contributions to the knowledge of plant

diseases in the Botanical Garden Bucharest. Lucr. Grad.

bot. 1959. 115-129. (Rev. Appl. Mycol. 39: 710, I960).

£liade,E. 1966, Uber das vorkmmen einiger Erysiphaceen in

j Rumanien. Reprium nov. Spec. Regni Veg. 73: 43-46.

(Rev, Appl. Mycol. 45: 482, 1966).

Ellert, C.W. 1966. Host range of the Erysiphaceae of Ohio,

The Ohio, J._Sci. 66: 570-581.

119

Epps, W.M. 1956. Gummy stem blight and other diseases on

cucurbits in South Carolina in the 1955 fall season.

PI. Dis. Reptr. AO: 439-A40.

Erwin, A.T. 1931. Nativity of cucurbita. Bot. Gaz. 91:

105-108.

Esenara, E.V, 1975. Occurrence of cucurbits powdery mildew

(Erysiphe cichoracearum DC) on Acalypha ciliata Forsk.

Nigerian Agricultural Journal 10: 258-259.

Esfandiari, E. 1947. Les Maladies des plantes cutivees et

des arbres fruities des regions Subtropicales du nord

del' Iran. Emt Phytopath Appl. Tehran. 5: 21 (Rev. Appl.

Mycol. 28: 378-379, 1949).

Fikry, A. 1936. Powdery mildew of cucurbitaceae. Bull. Minist.

Agrlc. Egypt 175, III. P 25 PI 24 (Rev. Appl. Mycol.

16: 364, 1937).

Fisher, R.W. 1959. Polybutenues-a promizing control for

powdery mildew. PI. Dis. Reptr. 43: 878-879.

Foex, E. 1912. Les "fihrinocorper" de 2opf et leurs relations

avec les corpuscles metachromatiques. Compt. Rend. Hebd.

Sean. Acad. Sci. 155: 661-662.

Foex, E. 1924. Notes surles Erysiphaceae (Notes on the

Erysiphaceae) Bull. Soc. Myc. de France. 11: 236-243,

(Rev. Appl. Mvcol. 4: 316, 1925).

Foex, E. 1925. Note sur quelques Erysiphacees. Bulj. Soc.

Myc. France 41: 417-438.

120

Fuckel, L. 1869. Symbolae Mycologicae. Beitr, Zur. Kenntn.

de Rheinischen Pilze. Jahrb. des Nassaulach. ver fur.

Naturk. 23: 76-86.

Gjaerum, H.B. 1956. Et. nytt mjoldoggmiddel. A new remedy

for mildews. Reprinted from Gartneryrket. 1956 pp A

(Rev. Appl. Mycol. 36: 258, 1957).

Glaeser, G. 1970. The occurrence of important causes of

injury to cultivated plants in Austria in 1964.

Pflanzenschutzberichte 41: 49-62. (Rev. PI, Path. 50:

275, 1971).

Glaeser, G. 1973. The occurrence of important causes of injury

to cultivated plants in Australia in 1971. Pflenzenschut-

zberichte 44: 113-126 (Rev. PI. Path. 54: 670, 1975).

Golovin, P.N« 1956, Monographic survey of the genus Leveillula

Arnuad. (Parasitic fungi-fam. Erysiphaceae) Trans« V.L.

Komarov. Bot. Inst. USSR Acad. Sci. Ser. 2: 195-308.

(Rev. Appl. Mycol. 37: 400, 1958).

Gordeeva, N.G. 1961, The relationship of ecological groups

of melon to fungal diseases. Shorn. Trud. Aspir molod.

nauch. sotrud, Veses. Inst. Rastenievod. 2: 288-293.

(Rev. Appl. Mycol. 42: 356, 1961).

Gorter, G.J.M.A. 1966. Powdery mildew fungus on cucurbits in

the Transvaal Provinceot South Africa. Nature, Lond.

209: 938.

121

Gorter, G.J.M.A, 1974. Methods of assessing cucurbit powdery

mildew (Sphaerotheca fuliginea) in terms of fungicide

evaluation. South. African J. ,Sci. 70: 7-91 (Rev. PI.

Pathol. 58: 828, 1974).

Gorter, G.J.M.A. 1966, Powdery mildew fungus on cucurbits

in the Transvaal Province of South. Africa. Nature,

Lond. 209: 938.

Gunguly, D. and V.R, Pandotra, 1963-1964. Important diseases

of mints and their control. Bull. Reg. Res. Lab. Jammu.

1: 42-48c

Hagen, A. 1952. Neue Bitrage Zur arktischen Pilzflora (New

Contributions to the Arctic fungus flora) Ber. detsch.

bot. Ges. 65: 96-99. (Rev. Appl. Mycol. 33: 450, 1954).

Hammarlund, C, 1925. Zur Genetick Biologie und Physiologie

Cinigen Erysiphacean. Hereditas 6: 1-126.

Hammarlund, C. 1945. Beitrage zur revision einiger imper-

feketon Mehltau-Arten Erysiphe polyphaga, n.sp. Bot.

Not. 1: 101-108.

Ifeshioka, Y. 1937. Relation of temperature and humidity to

Sphaerotheca fuliginea (Schlecht) Poll, with special

reference to germination, viability and infection.

Trans. Nat. Hist. Soc. Formosa 27: 129-145.

Hill, A.F. 1979. Economic Botany. Tata McGraw Hill Publishing

Co. Ltd., New Delhi.

122

Hirata, K. 1955. On the shape of the germ tubes of Erysipha-

ceae II. Bull. Fac. Agr. Nllgata Unv. 7: 24-36.

Hirata, K, 1966. Host range and geographical distribution

of the powdery mildews. Faculty of Agriculture; Nii^ata

University, Nllgata. Japan. A74. (Rev. Appl. Mycol.

45: 535, 1966).

Hirata, K. 1968. Notes on hostrange and geographical distribu­

tion of the powdery mildew fungi. Trans. Mvcol. Sco.

Japan 9: 73-88.

Homma, Y, 1933. Homothallism in Sphaerotheca fuliginea

(Schlect.) Poll. Proc. Imp. Acad. Tokyo. 9: 186-187.

Homma, Y. 1937. Erysiphaceae of Japan. J, Fac. Agric. Hokkaido

Univ. 38: 183-461.

Hooker, J. 1879. Oliver Fl. of Trop. Afr., II, P. 546.

Howard, F.L. 1934. Felicia amelloides vors. an unreported

host of Erysiphe cichoracearum DC, Phytopathology 24:

1315.

Humphries, J.E. 1893. Department of vegetable physiology.

Ann. Reptr. tfassachusetts State Agric. Exp. Sta. 10:

211-245.

Huttenbach, H. 1951. Echter Mehltau auf Kartoffein und

Gurken. (True mildew potatoes and cucumbers). Nach. Bl,

dtsch Pflsch Dienst (Brauns;chew) 37: 98-100. (Rev.Appl.

Mycol. 139, 1952).

123

Ikata, S. 1951. The diseases of food crops No.1 Rice plants

and beans (Series of plant pathology No.6). 2+12+320

pp., 26 PI. 94 figs., 1 graph, Tokyo. Asakura shoten.

(1951 Japanese) (Rev. Appl. Mycol. 31: 458, 1952).

Ivanoff, S.S. 1957. Powdery mildew pimples on watermelon

fruits. Phytopathology 47: 599-602.

Jacklewski, A.de. 1896. Monographie de Erysiphees de La

Suisse. Bull, de 2' Herbier, Biessier 4: 721-750.

Jaczewski, A.A, 1904. Year book of information concerning

diseases and injuries of cultivated and wild economic

plants. Jour. Mycol. 11: 170-179.

Jaczewski, A.A. 1927. Pocket key for the determination of

fungi part II. (Powdery mildew fungi). Published by the

A,A. Jaczewski Mycological Laboratory State Institute

of Experimental Agriculture Leningrad. 628. (Rev. Appl.

Mycol. 7: 346-347, 1928).

Jagger, I,C. 1926, Powdery mildew of muskmelon in the Imperial

valley of California in 1925. Phytopathology 16:

1009-1010.

Jagger, I.C. and G.W. Scott. 1937. Development of powdery

mildew cantaloupe. No.45 Circ. U.S. Dept. Agric, 441,

5 pp.

Jagger, I.C., T.W. Whitaker and D.R. Porter. 1938. A new bio­

logical form of powdery mildew on muskmelon in the

Imperial valley of California. PI. Dis. Reptr.22:275-276.

124

Janke, C , C.peter and A.Hellwig. 1977. On the occurrence

of the mildew genera Erysiphe & Sphaerotheca on

cucumber in the GDR. Archiv fur Phytopath Pflanzensch

13: 263-269.

Jhooty, J.S. 1965. Zinnia elegans a new host of S. fuliftinea

PI. Dis. Reptr. 49(9): 756.

Jhooty, J.S. and W.E.McKeen. 1965. Studies on powdery mildew

of s- rawberry caused by Sphaerothecea macularis.

Phytopathology 55: 281-285.

Jhooty, J.S. 1967. Identity of powdery mildew of cucurbits

in India. PI. Dis. Reptr. 51: 263-269.

Jhooty, J.S. 1971. Over wintering of powdery mildew of

cucurbits in Punjab, Indian Phytopath. 24: 441-445.

Jones, J,P. 1974. Fungicides for the control of target leaf

spot soil rot & powdery mildew of cucurmber. PI. Dis.

Reptr. 58: 636-639.

Junell, L. 1965. Nomenclatural remarks on some species of

Erysiphaceae. Trans. Br. Mycol. Soc. 48: 539-548.

Junell, L. 1967. Erysiphaceae of Sweden. Symb. Bot. Upsal.

19: 1-117.

Kable, P.F. and B.J. Ballantyne. 1963. Observations on the

cucurbit powdery mildew in the Ithaca district. PI.

Dis. Reptr. 47: 482.

125

Kapoor, J.N. 1967. C.M.I, descriptions of pathogenic fungi

and bacteria. No. 125-159 Kew, Surrey, England.

Katusuki, S. 1955. Parasitic fungus flora of Yaku Island

Kyushu. 1, J. Ja£. Bot. 30: 282-288. (Rev. Appl. Mycol,

35: 72, 1956).

Kaur, J. and J.S. Jhooty. 1985. Pathological specialization

in Sphaerotheca fuliginea causing powdery mildew of

cucurbits, Indian Phytopath. 38: 302-305.

Keyworth, W.G. 1959. Plant Pathology Report. Re£. nat. Res.

Sta. Warwiak. 9: 36-39.

Khadr, A.S. and Y.S- Abdou. 1972. Comparison of systemic

and contact fungicides for control of powdery mildew

on squash and cucumber. PI. Pis. Reptr. 56: 878-881.

Khan, A., M. Akram and A.M. Khan. 1974. Studies on powdery

mildews of cucurbits. H . Host range of Erysiphe

cichoracearum DC. Proc. 1st. Ann. Meet, Soc. Adv. Bot.

Meerut, India on p, 18.

Khan, A., M. Akram and A.M. Khan. 1978. Perithecia of

Sphaerotheca fuliginea (Schlecht) Poll, from certain

cultivated cucurbits. Aj;ta Bot, Indica, 6: 103-105.

Khan, A.M. 1972. Studies on powdery mildew resistance in

cucurbits. Technical Report PL-480 scheme. Aligarh

Muslim University, Aligarh, India. 100 pp.

1 b

Khan, A.M., M.W.Khan and K. Akram. 1971. Status of cucurbit

powdery mildew in India. Abs. Sec. Int. Symp. New Delhi 144-145

Khan, A.M., M.W.Khan and A. Khan. 1976. Studies on cucurbit

powdery mildew.II, varietal response of some cucurbits

to Spfaaerotheca fuliglnea. Indian Phytopath. 4: 306-308.

Khan, M.W. 1976. Studies on the cucurbit powdery mildew.IV

Intensity and identity of cucurbit powdery mildew in

Bihar. Indian Phytopath. 29: 314-315.

Khan, M.W, 1977. Perithecial stage of cucurbit powdery mildew

in Bihar. Geobios. 4: 210-211.

Khan, M.W. 1978. Coccinia cordlfolia and Lagenaria leucantha

differential hosts for powdery mildews of cucurbits.

PI. Dis. Reptr. 62: 161-164.

Khan', M.W. 1980. Powdery mildew in the Libyan Jamahiriya.II.

Identity at certain powdery Mildews Fungi Libyan J.

Agr. 9: 137-143.

Khan, M.W, 1981. Sphaerotheca fuliginea causing powdery mildew

of cucumber- A new record for Libyan Jamahiriya. Libyan

J. Agr. 10: 145-150.

Khan, M.W. 1982, Powdery mildew in the Libyan Jamahiriya.IV.

Identity of certain Powdery Mildew Fungi, Libyan J.

Agr. 11: 127-132.

Khan, M.W. 1983. The identity of powdery mildew of cucurbits-

A critical appraisal. Acta Bot. Indica 11: 97-126.

127

Khan, M.W. and A.M. Khan. 1970. Studies on the cucurbit powdery

mildew. I. Perithecial production in cucurbit powdery

mildew in Northern India. Indian Phytopath. 23: 97-502.

Khan, M.W., M. Akram and A.M.Khan. 1972. Perithecial stage of

certain powdery mildews including some new records.

Indian Phytopath. 25: 220-224.

Khan, M.W., A.M. Khan and M. Akram. 1974. Studies on the

cucurbit powdery mildew III, Intensity and identity of

cucurbit powdery mildew in Kashmir, Indian Phytopath.

27: 93-96.

Khan, M.W, and E.A. Mussa. 1979. Powdery mildews in the Libyan

Jamahiriya.I, Identity of certain powdery mildew fungi

Libyan J. of Agr. 8: 161-167.

Khan, M.W, and I,S, Faraj. 1982. Powdery mildew in the Libyan

Jamahiriya.III. Identity of certain powdery mildew fungi.

Libyan J, Agr. 11: 121-126.

Khosla, H.K,, G.S. Dave, and K,G, Nema. 1974. Identity of

powdery mildew on white gourd (Boenincasa hispida cogn.)

in Madhya Pradesh (Erysiphe cichoracearum).JNKVV.

Research Journal 8: 161-162.

Klika, J. 1922. Einige bemar kungen uber die biologie des

mehltaus, Ann. Mycol. 20: 74-80.

128

Kobakhidze, D.M. and K.G. Serova. 1974. Biological charac­

teristics of the pathogens of powdery mildew of cucumber,

Byulleten Vsesoyuznogo Nauchnoissledovatel skogo

Instituta Zeschity Rastenli No.29, 55-58 (Rev. PI. Pathol,

55: 963, 1976).

Kontaxis, D.G. 1977. Powdery mildew on watermelon fruit in

Imparial valley, California. PI. Pis. Reptr. 61: 397-598.

Kontaxis, D.G, 1979. Cleistothecia of cucurbit powdery mildew

in California - A new record PI. Pis. Reptr. 63: 278.

Kooistra, E. 1968. Powdery mildew resistance in cucumber

Euphytica. 17: 236-244.

Kowalski, J. 1966. Milek wiosenny (Adonis vernalis L.)

Jakonowy Zywiciel maizniaka wlasciwege Sphaerotheca

fuliginea (Schlechtendal). Salmen. (A. vernalis as a

new host of powdery mildew of S» fuliginea. Acta.

agrobot. 19:.5-16. (Rev. Appl. Mycol. 46: 303, 1967).

Kranz, J. 1962. Plant disease in cyrenaica. FAQ PI. Prot.

Bull. 10: 121-125.

Kumar, A. and V.R. Kumar, 1974. Temperature effects on

cleistothecium formation of cucurbits powdery mildew

Indian J. Mycol. PI. Path. 4: 201-202. (Rev. PI. Pathol.

55: 735, 1976).

Laibach, F. 1930. Uber die Bedingungen der Perithecium-

bildung bei der Erysiphaceen. Jehrb. Wis. Bot.72; 106-136,

129

Lafon, R,, Y, Bngaret, A. Beyries and A. Savio, 1966. New

fungicides effective against mildew cucurbits. Phytiat.

Phvtopharm. 15: 135-142.

Lall, C. and J.N, Gupta. 1965. Notes on powdery mildew from

India. Indian Phytopath. 18: 210-213.

Landel, J.P, 1961. In Garnaud J.C. (ed.) "Advances in

Horticultural Science and Their Application", Proc.

XVth Internat. Hort. Cong. Nice 1958 vol.1. 1961.

Oxford London. (Rev. Appl. Mycol. 41: 76, 1962).

Lebeda, A, 1983. The genera and species spectrum of cucumber

powdery mildew in Czechoslovakia. Phytopath. Z. 108:

71-77.

Leppik, E,E. 1966. Relative resistance of Cucumis sp.to

diseases and insects. PI. Intr. Invest. Paper 4: 1-8.

Leveille, J.H. 1851. Organisation et desposition methodique

des especes qui composent le genre Erysiphe. Ann.Sci.

Nat. III. 15: 109-179, 381 pp. 7-11.

Levykh, P.M. 1940. The influence of temperature and air

humidity on the infection of tobacco by powdery mildew.

(Oidium tabaci, Thuem). The A-I Mikoyan Pan Soviet,

Sci. Res, Inst. Tabacco and Indian tabacco, Indi.

(VITIM), Rostoffon Don. pub. 141, 97-111. (Rev. Appl.

Mycol. 20: 90, 1941.)

130

Locci, R. and M. Bisiach. 1972. Studies on powdery mildews.

I. Scanning electron microscopy of Sphaerotheca fuliginea «.

Revista di Patologica vegetala IV. 239-2A9 (Rev. PI.

Pathol. 52: 750, 1973).

Lozanov, P. and M. Vitanov. 1970. Studies on the susceptibility

of different melon varieties to powdery mildew (S.

fuliginea). Grad. Loz. Mauka 7: 67-76 (Rev. PI. Pathol.

50: 3347, 1971).

MacDonald, J.A. 1939. Powdery mildew on Cineraria. Gdnrs.

Chron. cv. 2721: 111. (Rev. Appl. Mycol. 18: 459, 1939).

Mahrshi, R.P. and B.S. Siradhana. 1980. Some new hosts of

Oidiopsis taurica from Rajasthan. Indian Phytopath.

33: 513o

Malay, O.C. and C.B. Skoland. 1969. Diseases of Mint. Ext.

Cire. Wash. _St. Coll. Ext. Serv. 357: 5. (Rev. PI.

Pathol. 49: 446, 1969).

Malik, K.A., M.W.Khan, M.Akram and A.Khan. 1973. Perithecial

stage of certain powdery mildews including some new

records. III. Indian Phytopath. 26: 698.

Marcelli, E. 1949. Osserve Zioni Prelimanari Sulla, special

zzazione dell Oidio del Tabacco, Notiz Malatt. Piante.

6: 19-21 (Rev. Appl. Mycol. 29: 386, 1950).

Mathur, R.L,, B.L.Mathur and C.P.Bhargava. 1971. New records

of powdery mildew from Rajastha. Indian Phytopath. 24:

63-65.

131

Mayor, E. 1947. Notes Mycologiques XII MvCological notes-

XII. Bull. Soc. neuchatel Sci nat IXX: 33-60 (Rev. Appl.

Mycol. 27: 158, 1948).

McCain, A.H. 1962. Powdery mildew of safflower. PI. Pis.

Reptr. 46: 203-204.

McKeen, CD. 1^54. Observations on the occurrence and control

of powdery mildew on green house cucumber in Ontario.

PI. Dis. Reptr. 38: 960-863. >

McLean, D.M. 1970. Powdery mildew on watermelon fruits. PI.

Dis. Reptr. 54{ 372.

Mc Nish, G.C. 1967. Powde ry mildew of cucurbits. J. Agric.

West Aust. Ser. 8: 223-224.

Medvendev, A.V. 1974, Selection of cucumbers for resistence

to powdery mildew. Byulleten Vsesoyuznogo Instituta

Rastenievodstva Imeni Ni Vavilova 41: 677-710. (Rev.

PI. Pathol. 54, 41: 677-710).

Meeuse, A.D.J. 1958. The possible origin of Cucumis anguria

L. Blumea suppl. IV. (H.J. Lam. Jub. Vol.) 196-204.

Menzies, J.D. 1950. Erysiphe cichoracearum DC. as a parasite

of potatoes. PI. Dis. Reptr. 35: 140-141.

Middleton, J.T. and C.E.Yarwood. 1946. Fungicidal control of

cantoloupe powdery mildew. Bull. Calif. Agric. Expl,

697, 1946. (Rev. Appl. Mycol. 26: 477, 1947).

132

Miller, P.A. 1938. Cucurbit powdery mildew on Carica papaya.

Phytopathology 28: 672.

Miller, P,A. and J.T.Barrett. 1931. Cantaloupe powdery mildew

in the Imperial valley, pp 1-36, Univ. of Cal. College

of Agric. Agric. Exp. Sta. Berkeley. California 507, 30 p,

Milbrath, D.G. 1927. Plant Pathology (Seventh Rept.) California

Dept. of Agric. for the period ending 31 December 1926)

Calif. Dept. Agric. Bull. 15: 131-133.

Minev, K. 1957. Investigation of the biology of tobacco

powdery mildew. Eryslphe cichoracearum DC. Feculty of

Agr. and Forestry Univers. Scopje. 10: 5-72 (Rev. Appl.

Mycol. 38: 627, 1959).

Misiga, S. 1966, Investigations of fugicides used against

powdery mildew II. Results of comperative trials with

dinocap and dinapacryle. Palnohospodarztvo. 12:

32-340 (Rev. Appl. Mycol. 45: 569, 1966).

Moore, F.J. 1952. Some powdery mildews on ornamental plants.

Plant. Path. 2:^53-55. (Rev. Appl. Mycol. 33: 380, 1954).

Moore, W.D. 1956. Powdery mildew (Erysiphe polygjoni) on garden

snap beans. Phytopathology 26: 1135-1144.

Morochkovskli, S.F. 1958. (Materials for the fungus flora of

the strelet sky steppe). J, Bot. Akad. Sci. Ukn., 15,

2, pp. 88-95. Russian and English (Summary) (Rev. Appl.

Mycol. 48: 448, 1959).

133

Morrison, R.M. 1960. Studies of clonal isolates of Erysiphe

ciChoracearum DC ex. Merat on leaf disc culture.

Mvcologla. 52: 388-392.

Morrison, R.M. 1964. Germination of conidia of Erysiphe

cichoracearum. Mycologia 56: 232-236.

Mont, R. and A.Villon. 1975. Translocation of Benomyle in

cucumis sativa L. and its protective action against

Erysiphe cichoracearum DC. Fitopathologica 10: 96-100.

(Rev. PI. Path. 55, -863, 1976).

Moseman, J.G. and H.R,Jr.Powers. 1957. Function and longevity

of cleistothecia of Erysiphe ^raminis f. sp. hordei.

Phytopathology 47: 53-57.

Moursi, M.A. and A.R.Sirry, 1956. The relation of nitrogen

and dusting with sulphur to the spread of powdery mildew

and yield of summer squash. Ann. Agric. Sci. Cairo 1:

313-317 (Rev. Appl. Mycol. 37: 624, 1958).

Movsesyan, L.I. 1967. Novye muchnistoro syanyegriby iz

Rostovskdi Oblasti U.S.S.R. (New Erysiphaceae from the

Rostov region of the U.S.S.R.) Ho.W.Sist.niz. Rost.

1967: 173-174. (Rev. Appl. Mycol. 46: 642, 1967).

Munjal, R.L. and J.N-Kapoor. 1973. Carica papaya. A new host

of Sphaerotheca fuliginea. Indian Phytopath. 20: 366.

134

Musarat, G. and S.Stephan. 1965. The occurrence of most

important disease and pests of Agricultural and horti­

culture plants in 1964 in the G.D.R. Nach. Bl. dt. p.

Schutzdientst, Berl. N.F. 19: 154-177.

Nagy, G.S. 1970. The identification of powdery mildews on

cucurbitaceae on the basis of conidial characteristics.

Acta Phytopath. Acad. Sci. Hung. 5: 231-248 (Rev. PI.

Pathol. 5: 177, 1972).

Nagy, G.S. 1972. Studies on powdery mildew of cucurbits I.

Host range and maintenance of Sphaerotheca fuliginea

and Erysiphe sp. under laboratory and glasshouse

conditions. Acta Phytopath. Acad. Sci. Hung. 7: 415-420.

(Rev. PI. Pathol. 53: 59, 1974).

Nagy, G.S. 1975. Revision of the powdery mildew species

Erysiphe polyplaga Hamm. Acta. Phytopath. Acad. Sci.

Hung. 10: 377-388.

Nagy, G.S. 1976. Studies on powdery mildews of cucurbits.II.

Life cycle and epidemiology of Erysiphe clchoracearum

and Sphaerotheca fuliginea. Acta. Phytopath. Acad. Sci.

Hung. 11: 205-210.

Nasyrov, 0, 1962. Diseases of cultivated and some wild plants

in the districts of the middle reaches of the Amu-Darya.

Izu. Akad.Nauk. Turkman. S.S.R. Biol. Sci. 46-53.

(Rev. Appl. Mycol. 32: 372, 1963).

135

Naudln, C, 1859. Revue des cucurbitacees cultivees on Museum

on 1859. Ann. _Sci. No Id. Ser. Bot. 12: 79-164.

Neger, F.W, 1915. Nachtrage Zum Eichenmehltan. Naturw Zelt

Forst. U. Landw. 13: 544-550.

Neger, F.W. 1923. Beitrage ZUF. Biologie der Erysipheen III

Der. Parasitismus der Mehltaupilzeline Art von gedul

deter symbiose (contributions to the biology of the

Erysiphaceae III. The parasitism of the mildew fungi-

a kind of tolerated symbiosis). Flora, CXVI, 3: 331-335.

(Rev. Appl. Mycol. 3: 157, 1924).

Nikiforova, N.A. 1962. The problem of powdery mildew of

cucurbit crops in Moldavia. Tr. Moldovsk. Naucha.

led. Inst. Oroshae mogo Zemledeliviai Ove Shehevoddrea,

4: 233-238 (Rev. Appl. Mycol. 43: 344, 1964).

Noble, R.J., H.J.Hynes, F.C.McCleery and W.A.Birmingham. 1934.

Plant diseases recorded in New South Wales. Sci. Bull.

Dept. Agric N.S.W. 46: 1-48.

Nomura, Y, 1974. Notes on parasitism of some powdery mildews

J. Ja£. Bot. 49: 30-32 (Rev. PI. Pathol. 53: 892, 1974).

Nour, M.A. 1957. Control of powdery mildew diseases in

Sudan with special reference to Broad bean. Egyp. J,

Exp. Agric. 25: 119-131.

Nour, M.A. 1959. Studies on the specialization of Sphaerotheca

fuliginea (Schlecht) Poll, and other powdery mildews.

Trans. Br. Mycol. Soc. 42: 90-94.

136

Omer, M.E.H. 1972. Chemical control of powdery mildews of

cucumber & okra in Sudan. Expt. Agric. 8: 255-270.

(Rev. PI. Pathol. 515: 797, 1972).

Osnitskaya (Mme) E.A. 1959. The biological reasons for pre­

ventive measures against powdery mildew of cucumber

in hot houses and forcing beds. Erude ni Inst. Qvostch

Khoz 2: 121-137 (Rev. Appl. Mycol. Al: 118, 1962).

Palti, J. 1953. Field observations on the humidity relation­

ship of two powdery mildews. Palestine J. Botany.

Rechswet. Ser., 8: 205-215.

Palti, J. 1962. Prediction of powdery mildew out breaks on

cucurbits on the basis of seasonal factors and host

range. Bull. Res. Counc. Israel. Sect. D. 10: 236-249.

(Rev. Appl. Mycol. 62: 199, 1962).

Palti, J. 1971. Biological characteristics, distribution and

control of Leveillula taurica (Lev.) Ann. Phytopath.

Mediter. 10: 139-153 (Rev. PI. Pathol. 51: 42, 1972).

Pangalo, K.I. 1930. Watermelons of the Northern hemisphere in

Russian, (English Summary) Bull. Appl. Bot. Genet, and

PI. Breed., 24: 41-48.

Pangalo, K.I. 1944. A new genus of the cucurbitaceae, Prae

citrullus m., an ancestor of the contemporary water

melon (Citrullus Forsk.) in Russian, English Summary.

J. Bot. de L' U.S.S.R. 29: 200-204.

137

Pangalo, K.I. 1955. Origin and evolutionary trends in cucur-

bitaceous crops. Probleray Botaniki Acad. Nauk. U.S.S.R.

2: 329-338.

Pantidou, M.E. 1971. Fungi of Greece VI. Erysiphaceae. Annls.

Inst. Phytopath. Benaki, N.S. 10: 187-203.

Parris, G.K. 1949. Cucurbit powdery mildews in Florida.

Florida Agr. Exp. Sta. Circ. 51: 6.

Passerini, G. (1867). Primo elenco di Funghi Purmensi. Comment.

Soc. Crittog. Italy. 2: 472-475.

Patil, S.D. 1964. Genus Sphaerothea Lev. in Maharastra. J.

Univ. Poona. Sci. Abstr. 1: 8543.

Patwardhan, P.G, 1965. Factors affecting the development of

the perithecial stage of powdery mildew of Helianthus

annuus L. in India. Mycopath. Mycol. Appl. 27:

253-256 (Rev. Appl. Mycol. 45: 272, 1966).

Paulus, A.O. 1969. Powdery mildew of cucurbit with systemic

and non systemic fungicides. PI. Pis. Reptr. 53: 813-816,

(Rev. Appl. Mycol. 49: 118, 1970).

Paulus, A.O., J.Nelson, F.Shibuya, T.W.Whitaker, T.House,

H.Meister and G.W.Bohn. 1972. Fungicides and methods

of application for the control of cautaloupe powdery

mildew. PI. Dls. Reptr. 56: 935-938.

Peleg, J, 1953. Out breaks and new records. Israel FAQ Plant

Prot. Bull. 14: 6O-6I (Rev. Appl. Mycol. 32i 424, 1953).

158

P e r a l t a , G.J- 1946-19^7. Appendix 6 . Report by the P l an t

P a t h o l o g i s t for the year (1946-1947. Rep. Dep. Agr ic .

Malta Oct 1938 to Sept . 1946 and A g r i c u l t u r a l year

1946-1947 (Rev. Appl. Mycol. 29 : 424, 1953) .

Peries, O.S. 1966. Host induced change in the morphology

of a powdery mildew fungus. Nature, London, 212:

540-541.

Peterson, P.A.D« and H.W.Johnson, 1928. Powdery mildew of

raspberry. Phytopathology 18: 787-796.

Petri, L. 1924, Osservazioni ed. esperienze sull• oidio

della Querce. Ann, Res. 1st Sup. Forest. Naz 9: 1-26

(Rev, Appl, Mycol, 4: 381, 1925).

Poretzkey, V.S. 1923. A new record of ascus stage of _S.

fuliginea (Schlecht) Poll, on melon. Plant diseases «

Monitor Phytopath. Sect. Chief Bot. Gard. R.S.F.S.R. 12:

86-88 (Rev. Appl. Mycol. 3: 665, 1924).

Power, H.R, and J.G. Moseman. 1956. Heterothallism in

Erysiphe graminis tritici. Phytopathology 46: 23.

Prasad, R,, J.P.Singh and M.K.Bhatnagar. 1968. Sphaerotheca

fuliginea on sunflower (H. annuus) a new record for

Rajasthan India. Indian Phytopath. 21: 449-451.

Pryor, D.E. and T.W.Whittaker.1942. The reaction of cantaloupe

strains to powdery mildew. Phytopathology. 32: 995-1004.

139

Pryor, D.E., T.W.Whittaker and G.N.Davis. 1946. The develop­

ment of powdery mildew resistant. Cantaloupes. Proc.

Amer. Soc. Hort. Sci. 47: 347-356.

Pucci, E. 1963. Actual situation of major plant diseases in

Libya. Ministry of Agriculture and Animal Wealth. PI.

Prot. Dept. Memograph.

Pucci, E. 1965. Lista Preliminare della Malattie della piante

ossorvate in Tripolitania. Dal-1959. Al-1964: Sintomi

Danni Lo Ha. Rivista di Agricoltura Subtropical e

Tropicale Anno. LI X No.7-9.

Raabe, R.D. 1964. Cleistothecia of a powdery mildew of Coral

bells. PI. Dis. Reptr. 48: 416-417.

Ragimov, U.A. 1961. Powdery mildew of cucurbits and control

measures in conditions of Western districts of

Azerbaijan, S.S.R. Trud. Ob' edin nauchn sessii Garuz

Azerb i. Arm s-Kh In- Tov Erekan 196: 141-147 (Rev,

Appl. Mycol. 43: 395, 1964).

Rajendran, V, 1965. A note on the occurrence of perfect stage

of bottle gourd powdery mildew in Mysore. Indian Phytopath.

38: 389-390,

Randall, T.E. and J.D.Menzies, 1956. The perithecial stage of

the cucurbit powdery mildew. PI. Dis. Reptr. 40: 255.

Rayss, T. 1947. Nouvelle contributiona 1'etude de' la mycoflare

de Palestine (quatrieme partie). Palest, J. Bot. Jerusalum

4: 59-76.

140

Reed, G.M. 1908, Infection experiments with the mildew

Erysiphe cichoracearum DC. Trans. Wise. Acad. Sci. 15:

527-547.

Reese, E. 1939. Additions to the powdery mildew flora of

Pennsylvania. Proc. Pa. Acad. Sci. XIII, pp. 70-75

(Rev. Appl. Mycol. 19: 364, 1940).

Reeves, E.L. and C.E. Blodgett, 1949. Diseases and disease

control in orchards irrigated by sprinkling. Proc.

Amer. Pomel. Soc. 63: 183-188.

Reichart, I., J.Palti, and B.Kapuler. 1943. Trials for

control of diseases of vegetables marroas. Bull.

Rehovoth. Agric. Sta. 33: 30 (Rev. Appl. Mycol. 23:

284-285, 1944).

Reuveni, R., J.Rotem. 1974. Effect of humidity on epide-

milogical patterns of the powdery mildew (S.fuliginea)

on squash. Phytoparasitica. 2: 25-33.

Revilla, V.A.1955. Control del oidium del melon Zapallo, Y.

pepino Bot Estac Expt. agric La Moline Loopp (Rev. Appl.

Mycol. 36: 164, 1956).

Rheede 1805. Malabar, III. Pis. 1, 5; Royle III Himal.,

p. -218.

Ristic, S. 1985. Contribution to the study of cucumber powdery

mildew, Erysiphe cichoracearum DC, in the glasshouse

with special reference to morphological and biological

characters.-Parazita Zastita Bil.ja. 36: 303-316.

141

Rochelle, L.A. 1972c Susceptibility of small sugar vegetable

marrow to mildew. Revista de Agriculture 47: 155-158.

Roder, K. 1937. Perithecia von. Erysiphe cichoracearum DC

em Salra. au Freilandgurken (Cucumis satlvus L.)

Angew. Bot., 19: 161-153 (Rev. Appl. Mycol. 16: 653,

1937).

Rodigin, M.M. 1936. Note on the powdery mildews of cucurbits.

(Sphaerotheca fuliginea (Sch.) Poll, and Erysiphe

cichoracearum Fr.) Sovetsk, Bot., 5: 120-123. (Rev.

Appl. Mycol. 16: 364-365, 1937).

Roxburgh, W. 1832. Flora India, III, p. 714, as L. clavata;

kurz contrb., 11 p. 100, Thwaites, Enum.

Rud, P.I. 1938. The life history of Sphaerotheca fuliginea

(Poll, on Calundula officinalis L.) Trans. Inst. Bot.

Univ. Kharkoff, iii, p. 79-101 (Rev. Appl. Mycol. 18:

615, 1939).

Rudenko, N.M. 1968. Vidovoi Sostavi bioekologicheskie

Osobennosti vozbuditelei rosy Tykevennykh Kul' tur

V uslo-viyakh Moldavii Specific composition and biological

characteristics of the causal agents of powdery mildew

of cucurbitaceae under Moldavian conditions. Trudy

Mo IdaV. nauchno issled. Inst. Orosh. Zembled. Ovoshch.

8: 133-I45c (Rev. Appl. Mycol. 48: 179, 1969).

Rudich, J., Z.Karchi and N.Eshed. 1969. Evidence for two races

of the pathogen causing powdery mildew of muskmelon in

Israel. Israel Jnl. Agrlc. Res. 19: 41-46.

142

Salmon, E.S. 1900c A monograph of the Erysiphaceae. Mem.

Torrey. Bot. Club. 9: 1-292c

Salmon, E.S. 1903. On specialization of parasitism in the

Erysiphaceae. Bot. Centrbl. Beiheifte 14: 261-315.

Sarbhoy, A.K., Lai Girdhari and J.L.Varshney. 1974. Additions

to the second supplement of fungi of India, Navayug

Traders,New Delhi.

Savulescu, T. 1929. Considerations systematiques Suz les

Erysiphacees. Ann. Sci. Acad. Hautes Etudea Bukarest.

1: 175.

Sawada, K. 1914. The classification of the Erysiphaceae based

on the conidial stages. Formosa Agr. Expt. Sta. Spaec.

Rep. 9: 1-102.

Sawada, K. 1959. Descriptive catalogue of Taiwan (Formosa)

Fungi, part XI. Special publication Coll. Agric. Nat.

Taiwan Univ. Taipei, Taiwan 8: 1-268»

Schlosser, E. 1972, Cleistothecia of Erysiphe cichoracearum

DC ex. Merat and conidia of Sphaerotheca fuliginea

(Schl.) Poll, concomitantly on cucumber, Meded. Fakul

Landbou. Gent. 37: 553-558. (Rev. PI. Pathol. 53: 4,

1974).

143

Schlosser, E, 1976a. Vorkomraen und verbreintung der beiden

arendes gurkenmehltaus Sphaerotheca fuli^inea and

Erysiphe clchoracearum, in der Bundesrepublic Deutschland.

Fac. Land bouww Rijks Univer Gent, 41: 539-544.

Schlosser, E. 1976b. Differentiation between conidia of the

two species of cucurbit powdery mildews, Sphaerotheca

fuliginea and Erysiphe clchoracearum. Nachrichtenbfatt.

des Deut-schen Pflanzen (Braunschweig) 28: 65-67.

Schlosser, E. 1979. Susceptibility of cucumber varieties to

the 2 pathogens of cucumber mildew, Erysiphe

clchoracearum DC ex. Merat and Sphaerotheca fuliginea

Schl. ex Fr. Gartenbauwissenschaft. 44: 217-219,

Schmitt, J.A.J. 1955. The host specialization of Erysiphe

clchoracearum DC, ex, Merat from Zinnia, phlox and

cucurbits. Mycologia. 47: 688-701.

Schnathorst, W.C. 1959. Spread and life cycle of lettuce

powdery mildew fungus. Phytopathology 49: 464-468.

Schanthorst, W.C. I960. Effect of temperature and moisture

stress on the lettuce powdery mildew fungus. Phytopathology>

50: 304-308.

Schnathorst, W.C. 1965. Environmental relationship in the

powdery mildews. Ann. Rev, Phytopath. 50: 450-454.

Schroeder, W.T. and R.Provvidenti. 1968. Systemic control of

powdery mildew on cucurbits with fungi 1991 applied as

soil drenches and seed treamtnets. . Dis. Reptr. 52:

630-632.

144

Schroeter, J, 1893. In Cohn's krypt Flora von Schlesien 3

(1908) 229-247. (Original checked by Commonwealth

Mycological Institute).

Schnathorst, W.C., R,C.Grogen and R.Bardin. 1958. Distribution

host range and origin of dettuce powdery mildew.

Phytopathology. 48: 538-543.

Shanmugasundarum, S., P.H.Williams, and C.E.Peterson. 1971.

Inheritance of resistence to powdery mildews in cucumber

Phytopathology, 61: 1218-1221.

Sharma, P.D. 1973. Occurrence of perfect stage of two cucurbit

powdery mildews in Northern India. Curr. Sci. 42:

871-872.

Simonyan, S.A. 1959. Powdery mildew (Erysiphaceae) of the

Armenians SSR (Part I) Trud. Bot. Inst. Akad. Nauk.

Armyan SSR 12: 93.

Siradhana, B.S. and S.L.Chaudhari. 1972, Occurrence of

Erysiphe cichoracearum and Sphaerotheca fuliginea at

Udaipur, Rajasthan. Indian J. Mycol. PI. Path. 2; 76-79.

Sitterly, W.R. 1978.. Powdery mildews of cucurbits. Page 359-

379 in D.M. spencer ed. ••The Powdery Mildews" Academic

Press, London, New York, San Francisco.

Sivakami, N., B.Chaudhary and B.Sen. 1972. Studies on causal

organisms of powdery mildew of cucurbits in India.

Proc. 59th Session of Ind. Sci. Cong, p. 510.

1A5

Smit, C.J. 1964. Healthier cucurbits for the Upington area.

Fmg. S. _Afr. 40: 23.

Smith, E.F. 1894. Peach mildew. Jour. Mycol. 7; 90-91.

Sohi, H.S. and S.K.Nayar. 1969. Some new records of fungi

from India. Indian Phytopath. 22: 410-412.

Sokolov, Y.U.V. 1978. Identification of the pathogens of

powdery mildews on cucurbitaceae in Astrakhan region.

Mikologiya i_. Fitopathologiya 12: 264-266. (Rev. PI.

Pathol. 58: 119, 1979).

Sokolov, Y.U.V., K.E. Dyutin and B.V.Kvasnikov. 1977. The

pathogen of powdery mildew of watermelon in the Astrakhan

region. Mikologiya _i. Fitopathologiya. 11: 171-172.

Sowell, G.J. and W.L. Corley. 1974. Severity of race 2 of

Sphaerotheca fuliginea (Schlecht) Poll, on muskmelon

introductions reported resistant to powdery mildew. Hort.

Science 9: 398-399.

Spencer, D.M., M.H.Ebeens, and W.M.Morgan. 1956. Microbiology.

Annual Report Glasshouse Crop Research Institute

Sussex U.K.

Spraygu, R. 1955. A restudy of apple powdery mildews in

eastern Washington. Wash. Agr. Exp. Sta. Bui. 560,

22 pp.

Spurling, A.T. 1973. A review of mildew problems on cucurbit

vegetables crops in Malawi. PANS 19: 42-45 (Rev. PI.

Pathol. 53: 146, 1976).

146

Steiner, J.A. 1908. Die spezia lisation der Alchemiffen

bewohenden Sphaerotheca humuli DC Burr.Centralb. Fur.

Bakt. 21; 677-736.

Stone, O.M. 1959. Annual Report 1959. Glasshouse Crop Research

Institute U.K. I4l pp.

Stone, O.M. 1962, Alternate hosts of cucumber powdery mildew

Ann, of Applied Biology. 50: 203-210.

Szembel, S.J. 1926. A new record of Sphaerotheca fuliginea

(Schlect) Poll, on melon. Morbi Plantarura Leningrad. 15:

51-52 (Rev. Appl. Mycol. 7: 219, 1928).

Szembel, S.J. 1930. Control of powdery mildew of cucumbers

by means of di-sodium hydrogen orthoarsenate. Comment.

Inst. Astra Chanensisad defensionum Platarium 2: 21-31.

(Rev, Appl. Mycol, 10: 500-501, 1931).

Tai, F.L. 1936. Notes on Chinese fungi VI. Bull. Chin. Bot,

Soc, 11: 16-28, (Rev, Appl. Mycol. 15: 746, 1936).

Tafradzhiiski, I. 1959. Powdery mildew on cucumbers in the

greenhouse and hot house industry and its control.

Gradinastwo 1: 22-25.

Tafradzhiiski, I. 1961. Experiments in the control of powdery

mildew, (Sphaerotheca fuliginea and Erysiphe cichoracearum

DC) on cucurbits. Nauch. Trud. Vissh. Sel kostop Inst.

Vasil Kolarov Plovdiv 10: 239-255.

147

Tafradzhuski, I. 1963. Powdery mildew on cucurbitaceae and

their biology Sphaerotheca fuliginea and Erysiphe

cichoracearum. Nauch. Trad. Vissh, Seiko Stop-Inst.

Vasil Kolarov. Plovdiv. 12: 233-248.

Tafradzhiiski, I. 1972. On the development condition of

powdery mildew I. Sphaerotheca fuliginea and Erysiphe

cichoracearum. Nauch. Trad. Vlssh. Seikostop. Inst.

Vasil Kolarov Plovdiu. 21: 99-107.

Tarr, S.A.J- 1952. Diseases of fruit and vegetables in the

Anglo-Egyptian Sudan. Bull. Min. Agric. Sudan. 9:

1-111.

Tarr, S.A.J. 1954. Diseases of economic crops in the Sudan

ii, Fibres, oil seeds, coffee & Tabacco. F.A.O« PI.

Prot. Bull. 11: 161-I65 (Rev. Appl. Mycol. 34: 137, 1955)-

Tarr, S.A.J. 1955. The fungi a«d plant diseases of the Sudan.

Commonwealth Mycological Institute. Kew,197 pp.

Teterevenikova-Babayan, D.N. and S.A-Simonyan. 1956. Powdery

mildew on cucurbits. Nauch. Trud. Erevansk. Univ.,

Ser. Biol. Sci. 6: 53-78 (Rev. Appl. Mycol. 37: 567,

1958).

Tilak, S.T, and Ram Chandra Rao.1967. Second supplement to

the fungi of India. Aurangabad Printers, Aurangabad.

Thomas, C.E. 1978, A new biological race of powdery mildew

of cantaloupes. PI. Pis. Reptr. 62: 223. (Rev. PI. Pathol.

11: 467, 1978).

1A8

Thompson, A, 1933. Division of mycology. Annual Report for

1932. Dept. of Agric. Strait Settlements and Fed.

Malay States (Reports of the Res. Econ. and Agric.

Educ. Branches for the year 1932). Bull. 14 Gen. Ser.

53-52 (Rev. Appl. Mycol. 13: 216, 1934).

Treboux, 0. 1914. Uberwintering vermittlest Mycel bei

parasitischen Pilzen. Mycol. Centrallatt. 5: 120-126.

Ubrizsy, G. 1946. Contributions to the knowledge of

Erysiphaceae of Nyirsey. Acta. Mycol. Hung. 3: 28-33.

Ullasa, B.A. and K.S.Amin. 1981. Simultaneous occurrence of

powdery mildews on Cucurbita maxima Dush. and Abelmoschus

esculantus (L.) Moench. from Karnataka, India. Curr.

Sci. 50: 238. (Rev. PI. Pathol. 6O: 462, 1981).

Ullasa, B.A., H.S.Sohi and K.S.Amin. 1979. Occurrence of peri-

thecial stage of Sphaerotheca fuliginea on muskmelon.

(Cucumis melo L.) from Bangalore (Karnataka State)

Curr. Sci. 48: 696-697.

Uozumi, T. and H.Yoshi. 1952. Some observations on the mildew

fungus affecting the cucurbitaceous plants. Ann. Phytopath.

Soc. Japan. 16: 123-126 (Rev. Appl. Mycol. 32; 466, 1953).

Vasudeva, R.S. 1957-58. Report of the division of Mycology

and Plant Pathology. Sci. Rep. Agric. Inst. N. Delhi.

1957-58. pp. 111-130, i960. (Rev. Appl. Mycol. 40:

652, 1961).

149

Vasudeva, R.S, 1960. The Fungi of India. I.C.A.R. New Delhi.

50 & 52o

Venkatakrishniah, N.S. 1954. Major diseases of crops. Mysore.

Agriculture Calender and Yr. Book. 1954,

Viennot-Bourgin, G. 1956. Mildious, oidiums, caries, Charbons,

rouilles, de plantes de France.Texte. Encyl. mycol. 26:

1-317.

Viennot-Bourgin, G. 1958. Contribution a la connaissance des

champiguous parasites de 1• Iran. Ann. Epiphyt.

97-270. (Rev. Appl. Mycol. 38: 132, 1959).

Viennot-Bourgin, G. 1969. Un Erysiphe due Haricot on Serre

(An Erysiphe species on French bean in the glasshouse)

Annls. Phytopath. 1: 473-489. (Rev. Appl. Mycol. 49:

318, 1970).

Viennot-Bourgin, G. 1971. New rare Erysiphaceae in France.

Ann. Phytopath. 3: 337-352.

Walker, M.N. and G.F.Weber. 1949. Disease of watermelons in

Florida. Bull. Fla. Agric. Expt. Sta. 459: 46 pp.

Weinhold, A.R. 1961. The orchard development of peach powdery

mildew. Phytopathology 51: 478-481.

Weiss, F. 1950. Index of plant diseases in the United State.

U.S. Dept. Agr. Plant. Pis. Survey Spect. Publ. 1263 p.

Whitaker, T.W. and G.N.Davis. 1962. Cucurbits: (Botany,

cultivation and utilization) Deonard Hill Books

Ltd., London.- 250 pp.

150

Whitner, B.F.Jr. 1956. Progress report on cantaloupe varieties

Proc. Fla.State hort. Soc. 69: 195-198.

Williams, D.H. 1941. Important diseases of glasshouse plants.

Fruit Grower 6l: 465-467. (Rev. Appl. Mycol. 20: 437,

1941).

Williamson, C.E. 1953. Powdery mildew control on some ornamental

plants. N.Y- . Flow. Gr. Bull. 93 pp. 2, 4 (Rev. Appl.

Mycol. 44: 558, 1953).

Woodward, R.C. 1927. Studies on Podosphaera leucotricha

(Ell. and Ev.) Salm. 1. The mode of perennation. Trans.

Brit. Mycol. Soc. 12: 173-204.

Yarwood, C.E. 1939. Powdery mildew of peach and rose.

Phytopathology 29: 282-284.

Yarwood, C.E.1944, Observations on the over-wintering of

powdery mildews. Phytopathology 34: 937.

Yarwood, C.E.1949. Effect of soil moisture and nutrient

concentration on the development of bean powdery mildew.

Phytopathology 39: 235-300.

Yarwood, C.E. 1956. Humidity requirements of foliage pathogen.

PI. Dis. Reptr, 40: 318-321.

Yarwood, C.E. 1957. Powdery mildews. Bot. Rev. 23: 235-300.

Yarwood, C.E. 1965. Predisposition of (Phaseolus vulgaris)

to mildew (Sphaerotheca fuliginea) by rust (Uromyces

phaseoli)infection, heat abrassion and pressure.

Phytopathology. 55: 1372,

151

Yarwood, C.E. 1973. Erysiphales in "The Fungi,IV A"- G.C.

Ainsworth, F.K.Sparrow and A.S.Sussman, Eds), pp.71-86.

Academic Press, New York.

Yarwood, C.E. 1978. History and Taxonomy of Powdery Mildews.

page 1-32 in D.M, Spencer ed. "The Powdery Mildews"

Academic Press, London, New York, San Francisco.

Yarwood, C.E. and M.W.Gardner. 196A. Unreported powdery mildews,

III. PI. Dis. Reptr. 48: 310.

Yarwood, C.E., S.Sidky, M.Cohen and V.Santilli. 1954. Tempera­

ture relations of powdery mildews. Hilgardia 22: 603-622.

Yossifovitsch, M. 1923. Contributions aL' etude de L'Oidium

de La vigne es son traitment 176 p. Thesis, Univ.

Toulouse,

Zacha, V. 1968. Padli Sphaerotheca fu'lifiinea (Schlect Fr.)

Poll, on a Okurkach (_S. fuli^inea on cucumber). Ochr.

Rost. 4: 159. (Rev. Appl. Mycol. 47: 657, 1968).

Zaracovitis, C. 1965. Attempts to identify powdery mildew

fungi by conidial characters. Trans. Br. Mycol. Soc.

48: 553-558.

Zeprometoff, N.G. 1925. Diseases of cultivated plants in

middle Asia. 165 pp. Uzbekistan Plant Protection Sta.

Phytopath. Sect. Tashkant (Rev. Appl. Mycol. 5: 174-175,

1926).

152

Zeprometoff, N.G. 1925. Attempt to identify powdery mildew

fungi by conidial characters. Trans. Br. Mycol. See.

A8: 553-558c

Zimmer, D.E, I96I. Powdery mildew on safflower. PI, Pis.

Reptro A5: 944.

Zopf, W„ 1887. Uber einen neuen Inhaltikorper in Pflanzlichen

Zellen. Bar. Deutsch Bot. Gessel 5: 275-280.