Results of the Second Year of Second-stage 

 Apple IPM Practices 



Ronald J. Prokopy and Susan A. Johnson 

 Department of Entomology, University of Massachusetts 



In a previous issue ofFniil Notes [53(2) :8- 11], we re- 

 ported on results in 1987 from the first year of our second- 

 stage IPM program in commercial orchards. Second- 

 stage IPM employs behavioral, ecological, and biological 

 approaches to pest management as a substitute for all 

 insecticide and miticide treatments after the last spray 

 against plum curculio in early June. The intent of second- 

 stage practices is not only to provide an environmentally 

 safe, cost-effective approach to controlling summer pests 

 that directly attack apple fruit (apple maggot, codling 

 moth, summer leafrollcrs) but also to alleviate insecticide 

 toxicity to beneficial predators/parasites of important fo- 

 liar pests such as mites, aphids, and Icafminers. Allowing 

 more natural enemies of foliar pests to flourish reduces the 

 need for pesticide treatment against foliar pests and 

 thereby lessens the rate (currently very high) at which 

 several of these pests are developing resistance to pesti- 

 cides. To emphasize further this latter goal, a major facet 

 of second-stage IPM is use during April, May, and early 

 June of pesticides least likely to be harmful to beneficial 

 predators and parasites. 



In the 1987 second-stage IPM tests, we compared 3 

 types of non-pesticidal approaches to intercepting apple 

 maggot flies before files penetrated the orchard interior. 

 These approaches were: (1) placing synthetic apple odor- 

 baited sticky red sphere traps every 10 yards in the woods 

 immediately surrounding a block of apple trees; (2) plac- 

 ing such spheres every 10 yards on perimeter apple trees 

 themselves; and (3) spraying perimeter (border row) apple 

 trees every 3 weeks from late June through August. In all 

 cases, abandoned apple trees within 100 yards of the or- 

 chard block perimeter were removed to preclude immi- 

 gration of codling moths and summer leafrollcrs. 



In 1988, we repeated the second and third approaches 

 in the same blocks as in 1987. The first approach (placing 

 spheres in woods) failed to control apple maggot flies to an 

 acceptable level. It was replaced in a different set of blocks 

 by a treatment that received border row sprays every 3 

 weeks from late June onward and that also received 

 releases of mite predators into the block interior. Each of 

 the 3 approaches used in 1988 was carried out on 6 test 

 blocks averaging 2 to 4 acres. Each test block was matched 

 with a nearby block of comparable size that received a 

 normal amount of spraying during June, July, and August. 



Apple Maggot Ffy Interception Traps on 

 Perimeter Trees 



In 1988 we doubled the density of odor-baited sticky 

 red sphere traps in perimeter apple trees from 1 trap every 

 10 yards to 1 trap every 5 yards. Results (Table 1) show that 

 average apple maggot fly captures per block in 1988 were 

 about 50% greater than captures in 1987 (compare 3201 in 

 1988 with 2054 in 1987). Non-baited sticky red monitoring 

 spheres were placed in the interior of each test block and 

 grower-sprayed block to provide an estimate of maggot fly 

 populations in the block interior. In 1987, 40% more 

 maggot flies were caught on monitoring traps in test blocks 

 than in grower-sprayed blocks. In 1988, only 11% more 

 were caught in the test blocks than in the grower-sprayed 

 blocks, reflecting the greater effectiveness of the higher 

 density of interception traps in 1988. This greater effec- 

 tiveness is also borne out by the low amount of maggot 

 injury to fruit in 1988 (0.5% in test blocks vs. 0.2% in 

 grower-sprayed blocks). In sum, the higher density of 

 interception traps in 1988 did a very good job of preventing 

 apple maggot flies from penetrating the block interior. 



Fruit injury by all other pests active after mid-June 

 (codling moth, red-banded leafroller, other leafrollcrs, 

 scale insects) was essentially the same (no greater than 

 0.2%) in test and grower-sprayed blocks in both 1987 and 

 1988. This result demonstrates the effectiveness of remov- 

 ing apple trees within 100 yards of the orchard perimeter 

 as a method of preventing movement of codling moths and 

 summer leafrollcrs into orchards (apple maggot flies move 

 over much longer distances and are little affected by the 

 tree removal method). 



In both 1987 and 1988, total Amblyseius fallacis and 

 yellow mite predators were about double in frequency in 

 the test blocks compared with the grower-sprayed blocks. 

 In 1988, pest mites in the test blocks were effectively held 

 in check by predatory mites despite no use of miticide 

 other than pre-bloom oil. In the grower-sprayed blocks, 

 where miticide was usually used in addition to oil, there 

 was a much less favorable pest-to-predator mite ratio. A 

 similar pattern held true for aphid predators in 1988: 

 nearly double the frequency in the test blocks. Together, 

 the results point out the predator-fostering value of com- 

 plete elimination of insecticide and miticide use after the 



