-7- 



Table 1. Approximate hours of wetting necessary for primary apple 

 scab infection at various temperatures. 



Average temperature °F 



Number of hours of wetting 



78 

 77 

 76 

 60-75 

 57-59 

 54-56 

 51-53 

 48-50 



47 

 45-46 

 44 

 43 

 42 

 33-41 



12 

 11 

 10 

 9 

 10 

 11 

 12 

 14 

 17 

 19 

 22 

 25 

 28 

 48 



From: Mills, W. D. 1944. Efficient use of sulfur dusts and sprays 

 during rain to control apple scab. Cornell Ext . Bui . No. 630. 



Long periods of rain in the early primary scab season made kick- 

 back spraying difficult in most cooperating orchards. In spite of 

 this, good scab and other disease control was achieved. Results for 

 the seven orchards are given in Table 2 below. 



Table 2. Comparison of results from disease management and control 

 blocks of seven orchards in the Massachusetts Apple Pest Manage- 

 ment Program, 1979. 



Criteria 



Disease management 



Control 



Average number 

 fungicide sprays 



Average dosage 

 equivalent^ 



Average % disease 

 on fruit at harvest 



Average fungicide 

 cost/acre 



10.6 

 9.8 

 0.99 

 $108.64 



13.0 

 11.1 



0.93 

 $130.93 



' . , ^ amount of fungicide used 



Dosage equivalent = average recommended rate of fungicide 



