Scab-Resistant Cultivars

Table of Contents

1. Introduction
2. Table 1: Selected Cultivars With Demonstrated Field Resistance to Some Apple Diseases
3. Table 2: Scab Resistant Apple 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 can hamper apple production in Ontario. Powdery Mildew incited by Podosphaera leucotricha, and the bacterial disease, fireblight, incited by Erqinia amylovora are also of major concern.

Several cultivars are now available which have high resistance of field immunity to apple scab. Table 2 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 (Table 1).

Combining resistance to several diseases in a new apple cultivar, as well as maintaining desirable fruit characteristics, have been formidable tasks. Some examples of cultivars showing some market potential are Liberty (Figure 1), Novaspy (Figure 2), Goldrush (Figure 3) and Enterprise. The level of reported disease resistance and the quality of the fruit produced for disease-resistant cultivars are outlined in Table 1.

Figure 1. Liberty apple.

Figure 2. Novaspy apple.

Figure 3. Goldrush apple

Resistance to other less prevalent diseases has not been included in disease resistance breeding programs. Susceptibility of the cultivars listed here to such problems as black rot, sooty blotch, fly speck, 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 a large planting of disease-resistant apples is attempted, diseases resistance, fruit quality, and most importantly, market availability should be evaluated under a growers' own set of circumstances. Because of the wide range of growing conditions in Ontario apple districts, the best way to evaluate these cultivars is to establish your own small planting of cultivars of interest.

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* 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.

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Scab-Resistant Apple 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	1933	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	1AAFC, 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

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