-26- 

 Table 1. Evaluation of disease-resistant apples in Massachusetts, 1983. 



Leaf symtpoms^ 



Cedar apple rust 



Scab 





 

 

 

 4 

 

 48** 



100*** 

 

 

 

 

 

 



% of 75 leaves on 3 trees with 2 or more spots/leaf- 



5 or more spots/leaf. 

 **Both leaves and fruit. 



All of the leaves and fruit of Imperial Mcintosh had significant scab lesions, while 

 all others were completely free from scab (Table 1). Sir Prize is very rust susceptible, 

 and respond accordingly. A few small, non-functional rust lesions were noted on 

 NY613452. Foliar black rot symptoms were more extensive than in 1982. An occasional 

 apple with black rot was observed for Macfree, NY613452, and Liberty (Table 1). This 

 may be a potential future concern if black rot innoculum continues to increase. For 

 comparison. Table 2 shows the disease-resistance ratings and commonly grown apple 

 cultivars from a test in New York State (Cornell University) published in 1983. 



Table 2. List of disease resistance of some apple varieties from New York test, 1983. 



Cultivar 



Resistance rating 



Apple scab Cedar apple rust fire blight Powdery mildew 



3 

 1 

 2 

 2 

 4 

 3 

 1 

 1 

 3 

 2 

 1 

 3 

 3 

 1 

 2 

 4 

 1 

 3 



3 

 2 

 2 

 3 

 3 

 4 

 3 

 2 

 2 

 3 

 3 

 4 

 2 

 2 

 3 

 2 

 2 

 4 



4 

 2 

 3 

 2 

 3 

 3 



3 

 3 

 4 

 3 

 3 

 3 

 2 

 3 

 2 

 2 



1 = very resistant. No control needed. 



2 = resistant. Control needed only under high disease pressure. 



3 = susceptible. Control usually needed where disease is prevalent. 



4 = very susceptible. Control always needed where disease is present. 



Acknowledgements: We thank Tony Rossi and others at the Horticultural Research Center 

 for maintaining the block and applying insecticides. This activity is supported by 

 the Massachusetts Cooperative Extension Service. 



