Apple (Malus domestica Borkh.)

M.K. Verma, Ph.D.Sr. Scientist (Hort)

Division of Fruits and Horticultural TechnologyIndian Agricultural Research Institute

New Delhi, Indiamahenicar10@gmail.com

Family: RosaceaeSubfamily: Maloideae (with pears)Genus: Malus (40 sp.)Section: MalusSeries: MalusSpecies: domestica

Taxonomy

•B.E. Juniper refers to both the domestic apple and the wild Central Asian apple as Malus pumila.

• The USDA has also adopted this convention.

•For clarity, and as Coart et al. 2006 use the older names: Malus sieversii for the wild Central Asian apple and Malus domestica for the orchard apple.

www.billnymanart.comBasic chromosome No. – x=17

2n= 34, 51, 68

OriginApple is known to have originated in south western Asia Caucasus region near Gilan in Turkestan and domesticated by Greeks and Romans a few centuries B. C.

It seems that M. sieversii played a seminal role in the origin of the cultivated apples. Other species that have probably contributed genes include

M. orientalis (Caucasian apple)

M. sylvastris (Crab apple)M. baccata (crab apple)M. mandshurica M. prunifoliaM. PumilaM. spectabilisM. prattiiM. astracania

The origin of the cultivated apple

Ancient Malus species ofChina: bird disseminated to Central Asia

M. Sieversii of CentralAsia

North Americabecame asecondary center of origin: ‘RedDelicious’,‘Golden Delicious’, etc.

Johnny Appleseed

Mammal disseminated

Diversity in Malus

Bloom

BloomM. baccata

Dormant“Kansas 14”

Early leaf fall

Late leaf fall

Fruit

‘Compilospecies’ hypothesis

Hypothesis: Malus domestica arose from some combination of crabapples in Eurasia, with possible recent introgression in North America (Watkins 1995)

Geography of M. sieversii

Harris et al. 2002 Note: What’s up with this map?

• Floral morphology• Fruit morphology

Morphological evidence for M. sieversii

Juniper and Mabberley 2006

Molecular evidence

Harris et al 2002

Wild apple: Malus sieversiiDomesticated apple: Malus domestica

cDNA gene matK• Only 16 of 1341 characters informative• 18-bp duplication in M. domestica and 1 M. sieversii accession Other M. sieversii accessions tested only for duplication, did not have it

Other genetic support for M. sieversii

• Morphological + RAPD + sequence data (ITS1, 5.8S rRNA, ITS2, matK) – Forte et al. 2002

• Isozymes DIA-2, AAT-2, PGM-1 and PGM-5 – Wagner and Weeden 1999

• Sampling? Strength of support? I don’t know…

Forte, A.V. et al. 2002. Phylogeny of the Malus (apple tree) species, inferred from the morphological traits and molecular DNA analysis. Russian Journal of Genetics 38: 1150-1160.

Wagner, I. and Weeden, N.F. 2000. ISOZYMES IN MALUS SYLVESTRIS, MALUS DOMESTICA AND IN RELATED MALUS SPECIES. Acta Hort. (ISHS) 538:51-56

M. sieversii hypothesis

• As the Tien Shan Mountains rose and the Gobi and Taklamakan Deserts grew, ancestral Malus populations were isolated

• Among a very diverse population making up as much as 80% of the forest,

• Some wild fruits are indistinguishable from cultivars • Selection by bears? • Human-mediated dispersal along Silk Road trade routes (but

not by current residents)(Juniper and Mabberley 2006)

Hypothesis: Malus sieversii of Central Asia is the wild ancestor of domesticated apples. Other species contributed little or nothing. (Vavilov 1930)

Malus domestica - the specifics

• Woody, long-lived tree• Unlike congeners, extreme heterozygosity, does not

breed true. Single parental event yields massive variation in fruit color, size, taste, flower color, thorns, tree habit, so…

• Cultivars must be vegetatively propagated – “instant domestication”

• Perfect, self-incompatible flowers. n = 17. Most congeners and cultivars 2n, some 3n, 4n.

NomenclatureIn 1753, Linneaus in his ‘Species plantarum’ used the name

Pyrus malus for the common cultivated apple.

Miller in 1768 proposed Malus as generic name for the apples including three species.M. sylvestrisM. PumilaM. coronaria

Poiret, 1804 given the name M. communis

Borkhausen, 1803 proposed the name M. domestica

M. x domestica Borkh is the proper technical name for the cultivated apples, owing to its interspecific origin.

History of Indian apple cultivationIn J. & K. apples have been grown as early as 2000 B. C., during the regime of Nara. Early cultivation was of indigenous varieties for local consumption. The earliest exotic apple plantation in Kashmir were established by the turn of the 16th Century.

Ancient records of Rajatarangi and Alberuni mention the existance of numerous varieties of apple in Kashmir.

Dried apples were called ‘Tsunt Hef’ and formed an important item of food in Kashmir during the winters. As it was considered a heat producing diet.

History of Introductions

Perhaps the first ever exotic introduction of apple were made 1820 at the Botanical Garden, Ooty (Tamilnadu) and later planted at Kodaikanal.

In H. P., the first apple orchard was established at Bandrole in Kullu Valley by Capt. A. A. Lee around 1860. Thereafter, many orchards were developed at Manali, Raison and Ngara by the Englishmen.

A number of varieties were introduced by Alexander Coutts in his orchard at Mashobra in 1887.

Popular Delicious varieties were introduced by S. N. Stoke, a resident of Philadelphia, USA in 1918 at Kotgarh in Shimla Hills

Home of Delicious apple

HistoryIn Uttarakhand

Apples were introduced in Kumaon and Garhwal region by Britishers in the later half of 19th Century after accession of this area in 1815 by defeating the Gorkha ruler of Nepal.

Apples were introduced by Mr. Allen and Mr. Smith into Kumaon Hills at Chaubatia around 1872. The first apple orchard was established in Ramgarh area of Nainital District.

Later many orchards were planted in Ramgarh, Bhoiali and Hartola areas.

The clonal rootstocks, propagated asexually, provide options in meeting the demands of modern orcharding such as uniformity, size control, precocity, cropping efficiency and resistance against certain adverse biotic and abiotic factors. The cultivation of apple has been shifted almost entirely to one or other of these clonal rootstocks all over Europe, USA, Canada and other apple-growing countries of the world.

Clonal RootstocksIt was early as 3oo years before Christ that the Alexander The Great sent dwarf apple trees back to Greece from his conquests of Asia.The ‘ Paradise’ which was named to a group of dwarfing rootstocks of apple perhaps selected from Persia, Paradise and Golden of Eden.Thereafter, due to large number of clonal rootstocks were grouped in to two categoriesParadise stocks:- hairy rooted having severe dwarfing effect.Doucin Stocks:- semi-dwarfing rootstocks.

Example:- Holly Leaf, Holstein, Doucin, English Broad Leaf, June-de-Mtz etc.

Malling and Malling Merton rootstocks

• The first successful effort to test and evaluate rootstocks was initiated at East Mailing Research Station, Kent, England, in 1912, which resulted in the development of Malling series of clonal rootstocks. The first series consisting of 16 stocks was given Roman numerals as “Malling I” and later on abbreviated to M I, M II and so on. Subsequently been raised to 27.

• First 25 were numbers in Roman numerals and all others beyond 25 are given Arabic numerals M 26.

• They were: M25 in 1956, M26 in 1965 and M27 in 1976, raising the total number to 27.

• During period of their popularization, Australia and New Zealand facing the serious problem of woolly aphid on the roots of apple trees. Mallling series were not found of any help.

• East Malling (HM Tydeman) and John Inns Research Institute (Merton) in England a total of 15 roostocks were numbered from MM 105 to MM115 in 1928.

Original botanical description of these rootstocks have been described by Tydeman (1953) and behaviour summarized by Perston (1953). Gammer(1953) reported propagation qualities of these crops

S. No. Resultant Progeny

Parents

1 MM. 101 Northern Spy x Malling I

2 MM. 102 Northern Spy x Malling I

3 MM. 103 Northern Spy x Bendavis

4 MM. 104 Malling II Northern Spy

5 MM. 105 Malling II X Northern Spy

6 MM. 106 Northern Spy x Malling I

7 MM. 107 Northern Spy x Malling XV

8 MM. 108 Northern Spy x Malling XV

9 MM. 109 Malling II X Northern Spy

10 MM. 110 Northern Spy x Malling I

11 MM. 111 Northern Spy x Merton 793 / Northern Spy x Malling II

12 MM. 112 Northern Spy x Winter Majestin

13 MM. 113 Northern Spy x Malling XII

14 MM. 114 Northern Spy x Malling XII

15 MM. 115 Northern Spy x Bendavis

• During the recent years, EMLA series of rootstocks, EM from East Malling and LA from Long Ashton, have been introduced. The EMLA rootstocks, which are designated as EMLA9 or M9 EMLA and EMLA106 or MM106.

• EMLA, are nothing but M or MM series of rootstocks which are free from known virus diseases prevalent in apple plantations in the United Kingdom. The new EMLA9, however, is much more vigorous than M9 and appears to be a different strain or clone, rather than simply virus free M9.

• In India, elaborate rootstocks trials were initiated on M and MM series of apple rootstocks soon after their introduction during sixties at Mashobra and Kotkhai in Himachal Pradesh, at Shalimar in Jammu and Kashmir and Chaubattia in Uttarakhand.

• These rootstock trials generated useful information on the performance of different clonal rootstocks under varying agro-climatic conditions.

• Many promising rootstocks have been identified and recommended for commercial use in different states. These included M7, M9, M26, MM106, MM111 in Himachal Pradesh, M2, M4, M7 and M9 in Jammu and Kashmir and M13 and MM106 in Uttarakhand.

Classification according to vigour groups

Very Dwarf (Weak) : M.IXDwarf (Medium weak) : M 26Semi Dwarf (Medium) : M VIISemi Vig. (Medium vig.) : M IV, MM 106, MM 111Vigorous : M I, II, XIII, MM 104 Very Vigorous : M XII, XVI, XXV, MM 109, MM 779

Other clonal rootstocks

Polish apple rootstocks• The Polish apple rootstocks (P series) have been developed with the principal

objectives of vigour control and tolerance to winter cold.

• Among the first series (P1, P2, P16, P18 and P22) have been found promising. Of these, P22, P2 and P16 are the most important.

• These 3 clones have been raised from crosses of M9 with Antonovka. All are winter hardy and resistant to collar (crown) rot. These induce good yield precocity and efficiency in the scion. However, these are susceptible to fire blight and Wooly Aphids.

• The P22 and P2 are as promising as dwarfing rootstocks and interstocks. Trees on P22 are extremely dwarf, while those on P2 are slightly more vigorous than those on P22.

• A second series of Polish apple rootstocks, P59, P60 and P92, have been released more recently, but these have not been tested extensively so far.

Russian apple rootstocks• Two types of apple rootstocks have been developed in Russia. Budagovsky (Bud

or B) series from and the Krasnodar clones (KC).

• The Budagovsky (Bud or B) series of rootstocks are cold hardy, providing adaptability to severe climate of Central Russia and cover full range of size control. Of the series, B9, B146, B490 and B491 are most important. B9, B146 and B491 are dwarfing, while B490 is a semi-dwarfing rootstock. B146 is the most dwarfing. Being similar or slightly more dwarfing than M27. B491 is between M27 and M9 in vigour; while B9 controls the tree size to a level between M9 and M26. B9 is the most extensively tested rootstock and its principal benefits are its extreme cold hardiness and resistance to collar-rot.

• Among Krasnodar clonal rootstocks, KC-1 (formerly 1-48-46) and 1-48-41 clones are important. These rootstocks were developed from crosses of M9 and M4 rootstocks with local varieties. Both these rootstocks are drought resistant and semi-dwarfing. KC-1 increases yield over the Malling rootstocks.

American apple rootstocks• The American apple rootstocks constitute a varied group of rootstocks that were

introduced from the breeding and selection programmes from Michigan, New York, Missouri, Kansas and Oregon.

• The Michigan apple clone (MAC) series of apple rootstocks were originated from open-pollinated seedlings from planting of Mailing rootstocks, Alnarp 2 and Robusta 5.

• In this series, MAC1, MAC9 (Mark), MAC24 and MAC39 are more promising.

• MAC1 is semi-dwarf. The trees on this rootstock are similar in size to those on M7, while MAC24 is semi-vigorous in vigour class of MM111. Mark (formerly MAC9) and MAC39 are dwarf rootstocks.

• Mark is most popular, producing trees slightly larger to those on M9, but similar to M26. Trees on Mark rootstock show excellent precocity, yield efficiency and good anchorage.

• Mark is also easier in propagation than M9.

Geneva (G) series formerly Cornell Geneva (CG) series• Developed at Geneva, New York, from McIntosh, Northern Spy and Malling clone

crosses. • G11, G13, G16, G30 and G65 are promising. • G11 is similar in size control to M26. • G16 is same as M9 in size control, but it is more precocious than M9. • G65 is half-way between M9 and M27 in size, but is precocious and productive. It has

good anchorage. • G13 is little more dwarfing than M7, while G30 is similar in size to M7, but is

precocious and has excellent anchorage.• These rootstocks are resistant to fire blight, G65 being almost immune to fire blight. • G65 and G30 are also resistant to collar-rot.

Besides G rootstocks, Geneva New York Station also introduced one clone, Novole (P1 286613) in 1982, as a rootstock. It is also resistant to fire blight, crown rot and tomato ring spot virus. It is easy to propagate by cuttings. Since it is a vigorous rootstock, it is recommended for use with dwarfing interstocks.

C series of apple rootstocks Developed by Stark Bros Nurseries in Missouri from the population of open

pollinated seedlings M8.

• Three selections, C6, C46 and C59 are promising. • C6 was introduced in 1974 for use as dwarfing interstem tolerant of

common latent viruses. Tree size control is similar to that of M9, when used as interstock or rootstock, and is similar in susceptibility to fire blight and Wooly Aphids, but is less brittle than M9. It is compatible with a wide range of cultivars, inducing very early and heavy production.

• K14 clone was selected at Kansas Agricultural Experiment Station in 1938 from a population of French crab that survived 2 intense summer droughts and a severe freeze. Since it is a very hardy rootstock, it is used as a hardy trunk stock or interstock.

• A dwarf clone, Oregon Apple Rootstock-1 (OAR-1), was selected for its growth control and outstanding anchorage.

Canadian apple rootstocks

• Ottawa series, Kentville stock clones and Vineland rootstocks. • 2 types, Ottawa Hybrid seedlings (OH) and Ottawa clonal (0) series.

• In OH series, 6 rootstocks (OH-1 to OH-6) were introduced in 1971. All these rootstocks are vigorous and tolerant to latent viruses commonly found in commercial apple cultivars.

• In Ottawa clonal (0) series, originally 10 clones (1 to 10) were selected of which Ottawa 3 and Ottawa 8 are promising. Ottawa 3 is between M9 and M26 in vigour. The principal benefits of Ottawa 3 are its better anchorage and much better hardiness than M9, but major constraint with it is extreme difficulty in propagation. The Ottawa 8 is a semi-dwarf rootstock, producing trees equivalent in vigour and productivity to those on MM106. It is the much hardier rootstock than MM106.

Robusta 5 is an important winter hardy rootstock. Originated by the Canadian Department of Agriculture in 1928 from the seed obtained from Siberia, it is a vigorous rootstock. It produces trees equal in size to apple seedlings. It is resistant to fire blight and easy to propagate.

Swedish apple rootstocksAlnarp2 (A2) and Bemali are important Swedish rootstocks. An introduction from Alnarp Fruit Tree Station, Sweden.

Alnarp 2 is a winter hardy and vigorous rootstock. It induces early bearing and productivity.

Bemali is an introduction from the apple breeding programme at Balsgard, Sweden, from a cross between Monk's Golden and M4. It is a dwarf rootstock with tree size in the range of M9 to M26. It is precocious and productive. Its anchorage is better than M9, but not as good as M26. Resistant to fire blight and Wooly Aphid, it is very easy to propagate.

Other new rootstocks

• Apple rootstock breeding programmes are underway in several other countries France, Germany, Belgium, Netherlands and Czechoslovakia.

• The principal objectives of these breeding programmes are: to develop apple rootstocks that are free from shortcomings of the important current commercial rootstocks, and also rootstocks which may be more vigorous than M27 and less vigorous than M26 and more suitable for high density planting.

• The Jork Research Station, West Germany, has released Jork 9 (J9) rootstock. It is a selection from population of open pollinated seedlings of M9. It is slightly more dwarfing than M26, inducing equal or slightly more production than M9 and M26. It is easily propagated in stool beds.

• The J.T.E. series of apple rootstocks from Czechoslovakia are under testing in many countries. Of which, three clones (F,G and H) are promising. Clone G has vigour similar to M27, clone F similar to M9 and clone H approximately 25 per cent greater than M9.

• French apple rootstocks, Pajam 1 (Lancep) and Pajam 2 (Capiland) are dwarfing and easier to propagate than M9. Trees on Pajam 1 are slightly smaller than M9 EMLA and Pajam 2, while Pajam 2 is similar to M9 EMLA in vigour.

5. Inter-specific hybridsColt Hybrid of P. avium x P. pseudocerasus developed at East Malling

Semi- dwarfing Becoming popular commercially for high density plantation.

M x M (Mazzard x Mahaleb )ClonesThese rootstocks are more precocious & productive than F 12/1Tolerant to nematodes

M x M 14 Dwarfing rootstockM x M2, M 39, M 60, M 97----- Resistant to Root rotM x M 14, M 39,M 60,M 97---- Tolerant to Canker

A) Drought Tolerant : Apple : MM 111, KC-1, KC1-48-41

B) Cold Hardy Apple : B 490, B 491, Bud-9(RLP), O-3, P2, P22, Novole,Alnarp 2.C) High Temperature Tolerant Apple : M-7, MM-109.D) High Soil pH Tolerant Apple : M-9, MM106, F) High Soil Moisture Tolerant Apple : M7,MM104, MM106,.

G) Disease Resistant Rootstocksi. Resistant to Powdery Mildew Apple : P1,P2,P16,P18,P22.ii. Resistant to Latent Viruses Apple : B 9, C 6, MAC 9, Novole.iii. Resistant to Crown & Root Rot Apple : B 9, B 491, G 30, G 65, MAC 9, O 3, P 2, Novole.

The IARI Regional Horticultural Station, Shimla

• Collected a number of wild and indigenous species for their evaluation as rootstocks for commercial cultivars.

• Of the 6 M. baccata types, M. baccata Rohru was observed to be more dwarfing than M9.

• M. baccata Shillong, M. baccata Khrot, M. baccata Gaibong and M. baccata Dhak, were as dwarfing as M9.

• The M. baccata Srinagar was observed to be semi-dwarfing, similar to MM106 rootstock.

• All these 6 types gave good grafting success with Golden Delicious apple. These were easy to propagate by stooling.

• The Malus baccata var. Himalaica is as dwarfing as M9 and has good compatibility with apple. It is resistant to collar rot, root rot and Woolly Aphid.

• The M. baccata var. Himalaica is used as a rootstock for apple in Uttaranchal and appears to hold promise as a suitable rootstock.

Modern breeding objectivesProduction of higher yields of good quality fruits as cheaply as

possible. In order to achieve this objective:- 1. Efficiency of the foliage.2. Structure of the tree to carry such weight3. Annual production.4. Good quality of the fruits- pleases the consumers.5. Good storage qualities.6. Early bearing7. Disease and pest resistance

Selection of Parents• Based on the object of the breeding programme• Either both parents must have the dominant character or

one must be.Example:-Resistant to Scab : Antinowka, M. baccata, M. sargenti, M.

seiboldii, M. zumi calocarpa, M. floribundaPodery mildew (Podosphaera leucotricha)resistant:-M. robusta,

M. zumi.Collar rot resistant (Phytopthora cactorum):- MM.103 Wolly aphis (Eriosoma lanigerum) resistant:-Northern Spy

Breeding technique

Flower colour- White to deep pinkProduced in the mixed bud in cymose clusters on spursSepals-5Petals-5Stamen-20Pistil-1 divided in to 5 styleOvary has 5 carpels each containing 2-ovules ( Maximm seed number is 10)Few cultivars have more than 10 up to maximum of 20.

• Pollen produced in great excess– 20 anthers– 3,500 pollen grains /

anther– 70,000 pollen grains /

flower– 5 stigmas / flower each

with 2 ovules– Approx. 7,000 pollen

grains / ovule

MethodsSelectionInbreedingOutbreeding (hybridization)Backcrossing

Apple pollination• Apples require cross pollination• Careful selection of pollen provider trees is necessary

– Pollen providers called “pollenizers”• Not all apple cultivars produce pollen that will fertilize

all other apple cultivars– Example: Winesap pollen is sterile

1.Anthesis (pollen shed)

2.Pollination (pollen transfer to a stigma)

tootherflowers

3.Pollen germination (on stigma)

4.Growth of germ tube to ovary

5.Fertilization of ovule

Pollination:-Mechanical transfer of pollen from anthers to stigma.

Flowers are collected at the balloon stage just before the petals expand, and before the flower dehisce.

Pollen collection :-Remove the anthers by rubbing with small comb, collect in Petri dish, keep in sunny side

Store in refrigerator for using within one month or store at -15 in deep freeze for one year

Quality testing with acetocarmine –glycerol (Marks, 1954) , determine under microscope

Viability test on a drop of sugar solution (2.5-20%), or 10% sucrose at 20-250 C

Emasculation of female parents, remove petals, sepals, stamens with nails of thumb and index finger before buds reaches balloon stage- 2 flowers per cluster

Pollen collection

Cross Pollination: dip brush in vial and touch the same on to stigma

Harvesting of fruits and removal of seeds

Development of varieties through hybridization

Stratification of seeds

3-50C ; 6-14 weeks

Juvenility:- period between germination to start of fruiting

Leaves are smallerFinely serratedShoots are thinnerProduced at right or obtuse angleNo flowers produced

Onset of adult phase

Development of flower buds

Transition phase

Lower part is still juvenile& upper part is adult

Ways of shortening juvenile period

• Four bark ringing which checks the growth • Grow the seedling as fast as possible in glass.• Budding on dwarfing rootstocks

Early selection

• Specialy disease infection through leaves such as scab, powdery mildew

• The plant growth parameters

Preselection criteriaAny positive correlation of this kind which is helpful to discard in

the nursery stage example:-1. pH of leaf sap the sweet type usually have pH 5.7 and the acid

type 5.5-5.6. 2. Colour of the fruits and anthocynin pigmentation of one year

shoot and petiole.3. Late leafing and late flowering.

Evaluation for the fruits

Fruits > 60mm diameter

Good colour e.g., clear yellow, bright red, bright green

Good apple flavoured

Sub-acid with pleasant flavour

Firm texture, plenty of juice

• A bud sport or mutation is a variant of an inherited character arising in a cell from which a bud eventually develop; this in due course produces a shoot and later a branch which differs, usually in one character, from the plant on which it was produced.

• They can affect any part of the plant.• Two types of mutations in apple:-• 1. Those which differs only single gene of tree

or fruits.• 2. Those which alter the ploidy • Varieties Most prune to bud sports:- Delicious,

Rome Beauty, Winesap, Cox’s Orange Pippin

Mutations and chimeras

If the mutation is limited to only one cell layer and therefore plants are chimera; since the gametes are formed from the sub-epidermal layer

Apple breeding Programmes

A large number of public and private breeding programmes around the world -33 countries. objectives

Jammu and Kashmir (Shalimar): Lal Ambri (Red Delicious x Ambri)Sunehari (Ambri x Golden Delicious)Akbar

Firdous Shreen

Himachal Pradesh (Mashobra) : Ambred (Red Delicious x Ambri)Ambrich (Richard x Ambri)Ambstarking (Starkign Delicious x Ambri)Ambroyal (Starking Delicious x Ambri)

Uttarakhand (Chaubattia) : Chaubattia Anupam (Early Sh. x Red D.)Chaubattia Princess (Early Sh. x Red D.)Swarnima (Benoni x Red Delicious)

Hybrids developed in India

Scab Resistant VarietiesVarietyVariety ASAS CRCR FBFB PMPM HarvestHarvestPristinePristine VRVR SS VSVS SS M. JulyM. JulyRedfreeRedfree VRVR VRVR SS SS E. Aug.E. Aug.LibertyLiberty VRVR RR RR SS L. Aug.L. Aug.SpartanSpartan MRMR RR MRMR RR E. Sept.E. Sept.Pixie CrunchPixie Crunch VRVR -- -- -- E. Sept.E. Sept.PriscillaPriscilla VRVR MRMR VRVR RR M. Sept.M. Sept.Crimson Crimson CrispCrisp

VRVR MRMR SS SS M. Sept.M. Sept.

EnterpriseEnterprise VRVR VRVR RR RR M. Oct.M. Oct.SundanceSundance VRVR VRVR VRVR VRVR M. OctM. OctGoldRushGoldRush VRVR SS RR SS L. OctL. OctAS= apple scab, CR= cedar apple rust, FB =fire blight, PM= powdery mildew AS= apple scab, CR= cedar apple rust, FB =fire blight, PM= powdery mildew

Scab Immune Varieties

PristinePristine

RedfreeRedfree