Scab-resistant cultivars

Excerpt from Publication 310, Integrated Pest Management for Apples,
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Table of Contents

  1. Introduction
  2. Table 4-6: Resistance of cultivars to apple scab and other diseases
  3. Table 4-7: Date of release of scab-resistant cultivars

Introduction

Apple scab, caused by Venturia inaequalis, is the most serious disease affecting apples. Growing cultivars resistant to apple scab eliminates the need for control of this fungal disease. Apple scab is not the only disease that hampers apple production in Ontario. Powdery mildew, caused by Podosphaera leucotricha, and the bacterial disease, fire blight, caused by Erwinia amylovora are also of major concern.

Several cultivars are now available with high resistance of field immunity to apple scab. Table 4-6. Resistance of cultivars to apple scab and other diseases, is a partial list of available scab-resistant apple cultivars, and additional selections are presently being developed. Some of these cultivars also have resistance to other diseases.

Combining resistance to several diseases in a new apple cultivar - and maintaining desirable fruit characteristics - has been formidable tasks. Examples of cultivars showing some market potential are Liberty (Figure 4-124), Novaspy (Figure 4-125) and Enterprise (Figure 4-126). The level of reported disease resistance and the quality of the fruit produced for disease-resistant cultivars are outlined in Table 4-6.
Figure 4-124. Liberty apple

Figure 4-124. Liberty apple (Dr. John A. Cline, University of Guelph)
Figure 4-125. Novaspy apple

Figure 4-125. Novaspy apple (Dr. John A. Cline, University of Guelph)
Figure 4-126. Enterprise apple

Figure 4-126. Enterprise apple (Dr. John A. Cline, University of Guelph)

Resistance to other less prevalent diseases has not been included in disease resistance breeding programs. Susceptibility of the cultivars listed here to problems such as black rot, sooty blotch, flyspeck, cedar-apple and quince rust, and other diseases remains largely undetermined. Such diseases might limit the adaptability of otherwise disease-resistant cultivars in some locations if no fungicide sprays are applied.

Before planting of large number of disease-resistant apples, evaluate diseases resistance, fruit quality, and most importantly, marketability of the cultivar. There is a wide range of growing conditions in Ontario apple districts, and the best way to evaluate these cultivars is to establish a small planting of cultivars of interest.

Table 4-6. Resistance of cultivars to apple scab and other diseases

Cultivar

Apple Scab

Pow-dery Mildew

Fire- blight Rust

Cedar Apple

Quince Rust

Best Use

Har-vest Season 

Storage (mths) 
Brief Desc.
of Major Attributes 
Belmac 

MR

U

U

U
dessert

late Sept.

3-4
Resembles McIntosh, skin smooth and glossy with up to 90% red, slightly stripped over a green background colour. Flesh is white, medium to coarse texture, mild sub-acid. Cold hardy.
Brite-
gold

R

R

R

S

S
dessert mid-
Sept.

1-2
Yellow, medium to large size, sweet, flesh creamy yellow, slightly coarse, tender and juicy. Bruises easily. Home garden use.
Dayton

R

MR

MR

S

S
dessert early-
mid-
Sept

1
80% to 90% attractive glossy red over yellow background colour. Flesh pale yellow, crisp, juicy, firm, fine-grained, and moderately acid. Reports that it is not cold hardy. Home garden use.
Enter-
prise

R

MR

R

R

U
dessert mid-
Oct

6
Medium fruit size, washed 80% to 100% medium red on a very bright and glossy green yellow background. Flesh is fine-grained, pale yellow to cream, firm, crisp, sub-acid. Has potential as a commercial cultivar. Late maturity limit its planting range for Ontario.
Free-
dom

R

MR

R

MR

U
dual early
Oct.

1-2
80% red stripes on a yellow background, large size. Flesh is creamy, juicy, firm, medium fine grained, tender and moderately acid. Fruit has prominent lenticels and fruit quality varies from year to year. Has potential as a commercial cultivar.
Florina (Que-rina®)

R

T

MR

U

U
dessert
U

U
Fruit 50% red on yellow background, firm, small to medium size, sweet flavour. Whitish-yellow flesh, very crisp, low acid. Deserves further evaluation.
Gold-
rush

R

MR

MR

S

U
dessert late
Oct

5-6
Fruit medium size, greenish yellow to red blush at harvest, becoming entirely deep yellow in storage. Flesh is medium to coarse grained, firm, fine-grained, mildly acid and pleasant aroma. Has potential as a commercial cultivar. Late maturity limits its planting range for Ontario
Jona-
free

R

MR

MR

S

MR
dessert early
Oct.

2-3
90% to 95% red, medium sized with pale yellow flesh. Crisp, juicy, very firm fine-grained, mildly acid and pleasant aroma. Has potential as a commercial cultivar.
Liberty

R

R

R

R

MR
dessert late
Oct.

4-5
90% dark red, with a yellowish background. Somewhat striped, moderately acid, flavour good. Flesh is yellowish, juicy, crisp with fine textured. Potential as commercial cultivar. One of the best SRC for McIntosh growing regions.
Mac-
free

R

MR

MR

R

S
dual early
Oct.

2-3
75% medium red over greenish yellow background, medium to small size. Flesh is juicy, white with a slight green tinge. Firm, moderately coarse, pleasant, moderately acid. Medium eating quality.
McShay

R

S

U

U

U
dessert mid
Sept.

2-3
70% dark red blush over a green background, similar to McIntosh. Flesh moderately firm, fine texture, juicy, mild flavour and low acid.
Moira

R

S

S

R

S
dual early
Oct.

2-3
Red, medium to small size, creamy white flesh with a green tinge. Medium eating quality.
Murray

R

R

MR

R

S
dessert late
Aug.

<1
Red, medium sized, flesh is soft, juicy, white with fine textured. Home garden use.
Nova
Easy-
gro

R

R

S

R

S
dessert late Sept.

2-3
Striped or washed medium red over a green yellow background. Medium sized, flesh is creamy white moderately fine, firm, crisp, moderately juicy and low acid. Home garden use.
Nova-
mac

R

MR

U

R

S
dessert early Sept.

3-4
Fruit medium size, 50% to 90% blushed or striped medium red with a greenish-yellow background. Flesh is creamy white, fine, tender, moderately crisp, juicy, and moderately acid. Similar to McIntosh. Has potential as a commercial cultivar.
Nova-
spy

R

MR

U

S

S
dual mid
Oct.

4-5
Similar to Northern Spy, greenish yellow striped or blushed with dark red. Flesh creamy yellow, fine, very firm, crisp, moderately tender, juicy and moderately acid. Has potential as a commercial cultivar.
Prima

R

MR

MR

S

S
dual mid
Sept.

1
60% to 80% bright red blush over a yellow background. Flesh is moderately acid, medium grained, crisp, and juicy. Tree lacks winter hardiness. Home garden use.
Prim-
evere

R

U

U

S

S
dessert mid
Oct.

6
Fruit bright and glossy dark cardinal red, slightly conical. Flesh is moderately coarse grained, pale green to white, firm crisp. Has commercial potential.
Priscilla

R

R

R

R

U
dual early
Oct.

2
70% to 90% bright red blush over a light yellow background. Flesh is crisp, medium grained, juicy, mild flavour and low acid with a licorice-like flavour. Fruit size can be small. Home garden use.
Pristine

R

R

MR

S

MR
dessert early Aug.

1
Fruit medium size, pale green-yellow at harvest, maturing to deep yellow, with moderate orange blush. Flesh is pale yellow, crisp, medium to fine grained, medium acid to sweet.
Redfree

R

MR

MR

R

S
dessert late
Aug.

1-2
80% to 90% glossy medium red on a yellow background. Flesh is firm, light cream, medium grained, crisp, juicy, mild flavour, low acid. Uneven ripening. Has potential as a commercial cultivar for late August to early September.
Aggressive thinning is required for fruit size and to avoid biennial bearing.
Rich-
elieu

R

MR

MR

S

S
dual early Sept.

2-3
Fruit 60% to 65% medium red, striped over green to light yellow ground colour, medium in size. Flesh white, tender, juicy, fine texture, mild to sub-acid.
Rou-
ville

R
susce-ptible to race 5

U

U

U

S
process early Sept.

2
Fruit large, 75% to 80% medium red lightly striped over pale green to yellow ground colour, medium in size. Flesh white, tender, juicy, fine texture, mild to sub-acid.
Sir
Prize

R

MR

MR

S

S
dual early
Oct.

2-3
Yellow, can have a slight red blush, can russett. Large, bruises easily, flesh is juicy, crisp, and very tender. Triploid, poor pollenizer. Home garden use.
Trent

R

MR

MR

R

S
dual late
Oct.

6
Red, medium to large in size. Flesh is firm, juicy, cream coloured with greenish tinge, and slightly coarse. Prone to bitter pit.
Wil-
liam's
Pride

R

MR

MR

R

S
dessert mid-
Aug

1-1.5
Moderately bright dark red on green-yellow or pale background. Medium to large size, flesh is light cream, medium-grained, mildly acid, very crisp and firm. Multiple pickings required. Prone to water core and bitter pit. Home garden use.

* Not all cultivars listed have been evaluated in Ontario. Where this is the case the information given is taken from the originating source.

Disease resistance ratings:

R - resistant (no control necessary)
MR - moderately resistant (control may be necessary under severe disease pressure)
S - susceptible (control necessary in growing areas where the disease is prevalent)
U - unknown
Storage - months in refrigerated storage at 1°C
Best use - processing: juice, sauce or pie fill; dessert: fresh fruit; dual: combined use
Harvest date - observed or estimated under Ontario conditions
SRC - scab-resistant cultivar

Table 4-7: Date of release of scab resistant cultivars

Cultivar

Year Released

Originated 1
Belmac

1996

AAFC, St. Jean, PQ
Britegold

1980

AAFC, SEF
Dayton

1987

PRI
Enterprise

1993

PRI
Freedom

1983

NYSAES, NY
Florina (Querina*)

1977

INRA, France
Goldrush

1973

PRI
Jonafree

1979

PRI
Liberty

1978

NYSAES, NY
Macfree

1974

AAFC, SEF
McShay

1988

Oregon State, Purdue & Illinois Univ.
Moira

1978

AAFC, SEF
Murray

1980

AAFC, SEF
Nova Easygro

1996

AAFC, Kentville, NS
Novamac

1997

AAFC, Kentville, NS
Novaspy

1978

AAFC, Kentville, NS
Prima

1986

PRI
Primevere

1970

AAFC, St. Jean, PQ & PRI
Priscilla

1972

PRI
Pristine

1994

PRI
Redfree

1981

PRI
Richelieu

1983

AAFC, St. Jean & PQ
Rouville

1983

AAFC, St. Jean & PQ
Sir Prize

1975

PRI
Trent

1979

AAFC, SEF
William's Pride

1988

PRI


1 PRI - Cooperative introductions from the State Universities in Purdue, Rutgers and Illinois
AAFC - Agriculture and Agri-Food Canada
AAFC, SEF - Smithfield Experimental Farm, Trenton, ON (closed)
NYSAES, NY - New York State Agriculture Experimental Station, Geneva, NY
INRA, France - Institute National de la Recherche Agronomique, Anggers, France




For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 21 July 2011
Last Reviewed: 21 July 2011