11 



Table 2. Percent clean and insect-injured fruit from experimental and 

 unsprayed apple trees. 



Experimental Neighboring 



orchard trees unsprayed trees 



Percent clean fruit 93.7 



Percent injury by: 



Plant bug 1.6 2.7 



Sawfly 0.6 8.7 



Curculio 3.5 96.0 



Codling moth 0.5 58.0 



Leafrollers 0.3 13.7 



Apple maggot 0.2 82.3 



Other 2.3 



problems experienced even in IPM orchards with outbreaks of mites and other 

 secondary pests are due in substantial part to detrimental effects on 

 beneficial predators and parasites as a result of insecticide, fungicide or 

 herbicide applications (even judicious use of selective materials) from June 

 onward. 



Can this approach used in the Conway experimental orchard be transferred 

 directly and successfully to larger commercial orchards? We doubt that it can 

 because of the amount and cost of labor that would be required to place and 

 maintain apple maggot traps in every apple tree. But variants of this approach 

 that are derived from knowledge we and others have gained of the behavior of 

 key apple pests over the past decade could prove successful. Thus, our recent 

 research on the host-finding behavior of sawfly, plum curculio, and apple 

 maggot adults has suggested that individuals entering an orchard from unsprayed 

 trees in nearby woods or hedgerows are most likely to visit first those apple 

 trees that are at the perimeter of the orchard and then gradually move into 

 interior trees. Because sawfly, plum curculio, and apple maggot populations, 

 as well as populations of every other key pest attacking apple fruit, originate 

 almost exclusively on unsprayed trees outside the orchard, intercepting these 

 insects at the perimeter of the orchard with traps (or spraying insecticide or 

 egg-laying deterring chemicals on the perimeter trees to prevent immigration 

 into the interior of the orchard) could constitute an effective variant of the 

 approach used in the Conway experimental orchard and allow us to enter the 

 second stage of IPM in Massachusetts apple orchards. 



At present, the only truly effective traps for direct control of a key 

 apple pest are traps for capturing apple maggot flies. Visual traps developed 

 for plant bug, sawfly, and leafminer adults are effective for monitoring 

 occurrence of adults and are being used extensively in first-stage IPM apple 

 orchards, but they have not proven effective as yet for direct control. 

 Chemicals that deter egglaying (either pheromones emitted by the adults or 

 chemicals emanating from plant tissue wounded by egglaying females) are now 

 known, from our recent research, to exist in sawfly, plum curculio, and apple 

 maggot. None of these chemicals has yet been identified as to structure or has 



