WELCOME

PERSENTATION ON DISEASES OF GUAVA

PRESENTED BYSUSHEEL KUMAR

Id. No. 48008M.Sc. 3rd YEAR

VEG. SCIENCE

GUAVA WILT

OCCURRENCE AND IMPORTANCE

Wilt is a pernicious disease of guava in India. In India the disease was first recorded near Allahabad in

1935 . The infection was reported 15 -30 %. The disease is a serious threat to guava cultivation in U.P.

In West Bengal it reduces the yield in affected orchard by 80% .

The disease is also prevalent in Haryana Rajasthan , A.P , Punjab and M.P.

It has forced uprooting of about 150 acre of guava orchard in Panjab and 300 acres in Haryana during 1971-81.

CAUSAL ORGANISM

The exact cause of the disease is still not fully understood but the pathogens viz. Fusarium oxysporum f. sp. psidii (Prasad, Mehta & Lal), Rhizoctonia spp. (Taub.) and various pathogens are reported by different workers may be the incitant of the disease.

Survival and spread: Through movement of plants containing sick soil in virgin

areas. Short distance spread is by water. Root injury predisposes wilt disease.

CONTI…..

Favourable conditions: High rainfall during August/ September. Stagnation of water in guava field for long duration. Maximum and minimum temperature ranges 23-32 °C with

76% RH are conducive. Lack of timely application of suitable control measures. There is severe incidence of wilt in alkaline soils at pH

ranging from 7.5 to 9.0 or in lateritic soils at pH 6.5 . Guava seedlings are more susceptible to F. solani as well as F.

oxysporum f.sp. psidii than older plants of 3 years age. On the other hand researchers reported that F. solani could

infect guava plants from 1-month-old to more than 4 years old.

SYMPTOMS

The leaves shed of premature , fruit size remain smaller, bare twig fail to develop new leaves and flower dry up. Browning and wilting of leaves from tip.

Discolouration of stem and death of branches and then the whole tree dry up.

The inner part of stem and root upto cambium and vascular tissues show a distinct discolouration.

DISEASE CYCLE

MANAGEMENT

Proper sanitation. Soil solarization. Uprooted and burnt wilted plants. Severe pruning followed by a drench with .2 % Benlate

or Bavistine 4 times in a year. Injection guava plant with 0.1 % water soluble 8-

quinolinol sulphate may provide protection against wilt for at least 1 year.

Use of resistant and tolerant varieties like , Allahabad Safeda , Dholka , Sindh etc.

ANTHRACNOSE

OCCURRENCE AND IMPORTANCE

Anthracnose is most common and important disease of guava in India, patricularly in U.P. ,Punjab and Karnataka.

It first reported from Saharanpur(U.P).

The disease also occur in Thailand , Philippines ,Bangladesh and Pakistan.

It also cause serious postharvest rotting of guava fruits.

CAUSAL ORGANISM Anthracnose is caused by Gloeosporium psidii,or colletotrichum psidii.

Survival and spread: Infection spreads by wind borne spores develop on dead leaves, twigs and

mummified fruits in the orchard. Dense canopy is congenial for germination of spores due to high moisture

condition. Movement of planting material through infected foliage. Transportation of fruits from high disease prone area.

Favourable conditions: Closer planting without canopy management The acervuli with pink spore masses are produced in moist weather on dead

twig and mumified fruits. Dew or rains encourages spore production and its dispersal around canopy. Temperature between 10 to 35oC with best 24 to 28oC.

SYMPTOMS

Fruit and leaf infection is generally seen during rainy season crop. Pin-head spots are first seen on unripe fruits, which gradually enlarge.

Spots are dark brown in colour, sunken, circular and have minute black stromata in the center of the lesion, which produce creamy spore masses in moist weather.

Several spots coalesce to form bigger lesions .

The infected area on unripe fruits become corky and hardy, and often develops cracks in case of severe infection.

Unopened buds and flowers are also affected which cause their shedding.

On leaves, the fungus causes necrotic lesions usually ashy grey and bear fruiting bodies at the tip or on the margin .

DISEASE CYCLE

MANAGEMENT

Three applications of Bordeaux mixture and Perenox (0.22 and 0.33%) after removal of dead twigs.

Spray of copper oxychloride and cuperous oxide (.3%) at weekly intervals effectively reduce the infection.

Apply Carbendazim 1gm/litre during June-September.

FRUIT ROT

OCCURRENCE AND IMPORTANCE

Phytophthora fruit rot cause extensive damage to rainy season crop of guava in Maharastra , Karnataka, Rajasthan ,Panjab and Haryana.

Sohni and Shridahar (1971) recorded 16.3 % loss to the crop before harvest in Mysore.

The post harvest loss are much higher.

CAUSAL ORGANISM Phytophthora nicotiana var. parasitica cause fruit rot of guava.Survival and spread: Rain and the wind are conducive for spread. The pathogen produces a great number of sporangia and spores on the

surface of diseased tissues principally when the temperature is near 25°C and this is an important sources of inoculum in the development of epidemics.

Spores spread from the infected plant material or soil by rain splashes. Favourable conditions: Cool, wet environmental conditions with high soil moisture favour

disease development. High humidity, temperature from 28-32oC (25 oC), poorly drained soils

and injuries are favourable for initiation of disease. Close plantation.

SYMPTOMS

The disease starts at blossom and stem end or even anywhere on the surface of well developed fruits.

The skin of the fruit below the whitish cottony growth becomes a little soft, turns light brown to dark .

Young, small and unripe fruits are more prone to infection. They become hard and woody.

On leaves the disease starts as small brown spots at margin or tip, spread fast and affected the entire lamina.

DISEASE CYCLE

MANAGEMENT Soil solarisation .

Destroy plant debris.

Sprays of Bordeaux mixture , copper oxychloride (.2%) and Dithane- Z- 78 (.2%) for control of guava fruit rot.

Six spray of Dithane- Z- 78 (.2%) at one month interval from June to November.

THANK YOU