-11- 



cations at high rates were necessary to "burn-out" or eradicate scab lesions. 

 Where rust control was essential, protective sprays were necessary before 

 all wetting periods (over 4 hours in length) as post-infection applications 

 of fungicides are not possible for rust management. 



Five- Year Summary 



A cost/benefit analysis for the five-year program is presented in Table 

 A. In each year of the program, disease management growers made fewer fungi- 

 cide applications, with fewer dosage equivalents, and reduced fungicide costs, 

 compared to control growers. Per cent diseased fruit at harvest in disease 

 management orchards was either comparable to or only slightly higher than in 

 control orchards. Disease management benefits per acre were variable, but 

 always positive for cooperating growers. 



When we examined the results for a five-year period, three trends became 

 evident to us. The first was that disease management benefits are most likely 

 to occur at a higher dollar level in dry spring seasons, as in 1980, rather 

 than in wet ones, as in 1982. With fewer wetting periods, greater efficiency 

 can be achieved in timing post-infection sprays. 



The second trend is that continued benefits from disease management de- 

 crease in magnitude with time. Fungicide sprays and dosage equivalents can- 

 not be further reduced in number every year. Many control growers have also 

 begun to adopt disease management practices, obtained from the numerous Ex- 

 tension education programs we have been involved in over the past five years. 

 It is becoming increasingly difficult to find control orchards where only 

 traditional methods are used. 



Per cent disease incidence for the five-year period is summarized in 

 Table 5. Apple scab incidence has been reduced. The trend for calyx end 

 rots, however, is increasing slightly. Timing sprays only for scab manage- 

 ment may have increased infection possibilities for end rot fungi before 

 or after bloom. Using fungicides that are good for scab management may also 

 mean that they are not as good for end rot management. Anytime a practice 

 is changed, we can expect that new problems may develop. The use of one or 

 more sprays of a protective fungicide, rather than a "post-infection" or 

 "kick-back" material, from tight cluster to petal fall, should eliminate 

 calyx end rot problems, especially during wet growing seasons. 



Acknowledgements : 



We have been able to obtain considerable information about apple disease 

 management during the last five years. We could not have done this without 

 the enthusiastic and generous support and cooperation of the participating 

 Massachusetts fruit growers. 



This program was supported by special funds from the USDA, by the Massa- 

 chusetts Cooperative Extension Service, and the Massachusetts Fruit Growers 

 Association. 



