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DISEASE MANAGE^fENT FOR APPLES IN MASSACHUSETTS: 

 1982 RESULTS AND SUMMARY OF THE FIVE-YEAR PROGRAM 



Christopher M. Becker,^ Ted R. Bardinelli,2 

 Daniel R. Cooley,^ Kristin G. Pategas,^and 

 William J. Manning^ 



Department of Plant Pathology 

 University of Massachusetts, Amherst 



The five-year pilot program to develop and evaluate new and innovative 

 apple disease management practices in Massachusetts terminated in 1982. Our 

 results for 1982 and a summary of the entire program are presented here. 



1982 Results 



In 1982, 13 commercial apple orchards were involved in the program. Four 

 followed traditional disease management practices and served as controls for 

 comparisons. The other 9 were visited by scouts on a regular basis and ap- 

 plied fungicides to manage apple scab (and other diseases) on a "post-infection" 

 basis only. Hygro thermographs were used to determine when infection periods 

 had occurred and when fungicides should be applied. A more complete descrip- 

 tion of the disease management program can be found in Fruit Notes 46(1) pp. 3-4. 



Like many growing seasons in Massachusetts, 1982 was unusual. New green 

 apple leaves emerged at the same time that mature ascospores of the scab fungus 

 were available. Two extensive Infection periods occurred in late May with heavy 

 inoculum released. Primary scab season ended on 4th June. A complete summary 

 of wetting and infection periods for 1982 is given in Table 1. 



Fungicide usage and fruit disease incidence for disease management orch- 

 ards are given in Table 2. Results for control orchards are In Table 3. 

 Disease management orchards averaged one less fungicide application. Reduc- 

 tion in dosage equivalents (2.6 fewer than controls), however, resulted in 

 savings of $32 per acre for fungicides. Disease management orchards had a 

 slight increase in per cent diseased fruit at harvest when compared to con- 

 trols. Savings realized with reduced fungicide costs, however, more than 

 offset the slight increase in costs due to a few more diseased fruit at 

 harvest. 



Paired t-tests were used to compare results from disease management and 

 control orchards (Table 4). No significant differences (P = 0.05) were found 

 between the number of fungicide applications, per cent diseased fruit at har- 

 vest, and dollar losses from disease. There was a significant difference 

 between actual fungicide usage, or dosage equivalents, and fungicide costs 

 per acre. Disease management growers used less fungicide without significant 

 increases in fruit diseases at harvest. 



Variation in the number of fungicide sprays (8-14) and dosage equivalents 

 (5.67-11.88) in IPM orchards is closely related with both efficiency in timing 

 of scab sprays, and the necessity for fungicide applications for diseases other 

 than apple scab, especially the rusts, and powdery mildew. When post- infec- 

 tion scab sprays were too late to Inhibit apple scab infections, or poor cover- 

 age was achieved by spraying during windy weather, additional fungicide appli- 



llPM Technician 1981-82 ^IFH Technician 1978-80 3Extension Technician 

 ^IPM Scout ^Professor of Plant Pathology 



