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The results show that grower C realized a net profit of 

 $63.60 more per acre from the alternate middle than the every 

 middle plot. An additional benefit was that the grower could 

 spray the alternate middle plot in about half the time as the 

 every middle plot. This allowed him to respond more rapidly to 

 conditions calling for immediate pesticide application. 



We conclude from our first 2 years of experimentation that 

 an alternate middle spray program in Massachusetts shows promise 

 of effectively controlling most of the major insect pests that 

 attack the fruit. To date, it has proven just as effective as an 

 every middle program against those pests which are highly mobile, 

 and hence make frequent contact with the sprayed portion of the 

 tree: codling moth, redbanded leafroller, and apple maggot. In 

 some situations, the alternate middle program may be slightly less 

 effective against a pest like plum curculio, whose mobility within 

 the tree is quite restricted (see Fruit Notes 42(4) :5-7). Where 

 such is the case, every middle treatments for the petal fall and 

 first cover sprays would be advisable. The alternate middle pro- 

 gram's effectiveness against spider mites and aphids may depend on 

 the type of pesticides employed. On the one hand, spider mites 

 and aphids are not very mobile. On the other hand, if not killed 

 by toxic orchard pesticides, predators are capable of effectively 

 suppressing spider mites and aphids below damaging levels (see 

 Fruit Notes 42(2) : 5-7 and 42(6) : 6-10) . 



In summary, our findings to date show that the alternate 

 middle spray program can result in greatly reduced pesticide usage, 

 effective pest control, and a greater net profit to the grower. 

 For those growers interested in trying out the program, we would 

 suggest starting with a one or two-acre block to see how the pro- 

 gram works with your particular type of sprayer and trees, and 

 under your particular local insect, mite, and disease conditions. 

 We would advise against submitting large acreage to this program 

 until you (and we) learn more about the program's long-term effec- 

 tiveness and possible shortcomings. For example, we need much 

 more information on its effectiveness against plum curculio and 

 apple diseases. Present knowledge suggests that the program works 

 best where the trees are well pruned (open centers) and spaced at 

 recommended intervals (not wider) . 



