Do Lepidopteran Pests of Apples in 

 Commercial Orchards of Massachusetts 

 Increase Under Multi-year Absence of 

 Summer Insecticide Sprays? 



Ronald Prokopy, Starker Wright, Jennifer Mason, and Jonathan Black 

 Department of Entomology, University of Massachusetts 



Among insects that attack apples in New England, 

 pests such as tarnished plant bug, European apple 

 sawfly, plum curculio, and apple maggot normally are 

 the ones against which most insecticide sprays are 

 directed. Fortunately, we do not often experience 

 damaging populations of lepidopteran pests such as 

 codling moth, lesser appleworm, or leafrollers in our 

 commercial orchards. Such lepidopteran pests are, 

 however, an annual threat to apple quality in 

 commercial orchards in other regions of North 

 America. 



There are two principal reasons why we usually 

 see rather little evidence of these kinds of lepidopterans 

 in most New England orchards. First, organophosphate 

 insecticide sprays directed against plum curculio and 

 apple maggot also act to control these lepidopterans. 

 This would not be the case if the lepidopterans were 

 resistant to organophosphates, but possible resistance 

 has turned up in only a handful of New England 

 orchards and only in the case of obliquebanded 

 leafroller. Second, under the relatively cooler climatic 

 conditions of New England, these lepidopterans rarely 

 have more than two generations per year. In warmer 

 climates, three or more generations are common 

 (especially for codling moth). The threat to fruit quality 

 increases as a direct function of number of generations 

 per year. 



Recently, some New England growers who market 

 their apples directly to consumers have shown 

 increased interest in adopting advanced-level integrated 

 pest management (IPM) practices that involve 

 controlling apple maggot with odor-baited red sphere 

 traps rather than spraying apple maggot with 

 insecticide. Without insecticide coverage of fruit 

 beyond residual activity of the last spray against plum 



curculio in June, second generations of codling moth, 

 lesser appleworm, and leafrollers could pose a threat 

 to fruit quality in orchards practicing advanced-level 

 IPM. The threat could become increasingly greater 

 over successive years as populations build internally 

 in orchards during July, August, and September in the 

 absence of insecticide. 



Here, we report results of a study of damage to 

 apples by lepidopteran pests in blocks of apple trees in 

 commercial orchards in Massachusetts where, for eight 

 consecutive years, no insecticide was applied to the 

 blocks after mid-June. 



Materials & Methods 



Each test block was about one-half acre in size and 

 was accompanied by a nearby comparison (check) 

 block that annually received two or three sprays of 

 azinphosmethyl or phosmet during July and August to 

 control apple maggot. All test blocks received odor- 

 baited red spheres on perimeter apple trees to control 

 apple maggot, but no insecticide after the last spray in 

 mid-June against plum curculio. One test and one 

 check block were located at comers of a larger block 

 of apple trees in each of six commercial orchards. 

 Blocks were comprised of Mcintosh, Cortland, Empire, 

 or Delicious apples. The study extended from 1 99 1 to 

 1998. 



Annually at harvest, 200 fruit were sampled per 

 block for injury by lepidopteran pests. 



Results 



Results for each pest are presented in the form of 

 regression lines (Figure 1) that depict a trend toward 



Fruit Notes, Volume 66, 2001 



11 



