aimed at managing apple insect and mite pests without Ackowledgements 

 use of insecticide and miticide after early June. Even 

 so, we believe that this aim will be more fully achieved 

 at eventual lower cost by adopting the second-stage 

 IPM practices set forth in the preceding article. 



We thank the Massachusetts Society for the Promotion 

 of Agriculture and the Joint federal/state apple IPM 

 project for supporting our work on second-stage apple 

 IPM in 1989. We also thank Kathleen Leahy, Dave 

 Stanley, and Patti Powers for their assistance in sam- 

 pling orchards. 



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Evaluation of Releases of Amblyseius fallacis 

 Predatory Mites on Apple Trees 



Ronald J. Prokopy and Margaret Christie 



Department of Entomology, University of Massachusetts 



David Stanley 

 Biokon Insectaries 



One of the major aims of apple IPM is to promote 

 predatory mites as a substitute for chemical miticides 

 to control European red mites and two-spotted spider 

 mites. We envision 2 major methods of promoting 

 predatory mites: (1) using second-stage IPM practices 

 of non-use after early June of any pesticide even 

 slightly harmful to predatoiy mites (this includes vir- 

 tually all insecticides and miticides currently labelled 

 for orchard use, and some fungicides, especially beno- 

 myl and mancozeb) or (2) release into orchards of 

 laboratory-cultured predatoiy mites that have been 

 selected to resist major types of insecticides, such as 

 organophosphate and carbamate compounds. The 

 first option may be the less expensive one, but resident 

 or immigrating predatoiy mites could still be adversely 

 affected by early-season pesticide use. Here, we report 

 on 2 years of experiments in commercial orchards 

 evaluating the second option. 



Methods Used 



In 1988, we selected 2 experimental blocks (each 

 about 1 acre) in each of 6 commercial orchards. One 

 block (the first-stage IPM block) was treated normally 

 by the grower, using the first-stage IPM practice of 

 applying pesticide when pest monitoring information 



indicated the need to do so. The second block (the 

 second-stage IPM block) was treated identically to the 

 first-stage block through early June. Thereafter, each 

 second stage block received only a border row spray ap- 

 plication of insecticide on perimeter apple trees every 

 three weeks until harvest. No insecticide or miticide 

 was applied to the second-stage block interior after 

 early June. For essentially all blocks, only Imidan™ or 

 Guthion™ as insecticide was applied after early June. 

 This protocol was followed in both 1988 and 1989. 



In 1988, we released in July approximately 500 

 adults of the predatory mite Amblyseius fallacis under 

 each of 7 trees per block in both first-stage and second- 

 stage blocks in all 6 orchards. In 1989, we tripled the 

 number of A fallacis released in July to reach a level of 

 about 1 500 per each of 7 trees per block in both types of 

 blocks. However, they were released on tree foliage 

 rather than on the ground (as done in 1988), and were 

 released in only 4 of the 6 orchards. The predators 

 originated from a strain in Geneva, New York that has 

 been determined to be resistant to most organo- 

 phosphates, and possibly also to some carbamate insec- 

 ticides. The predators were cage-reared on two-spot- 

 ted mites cultured on bean leaves. Predators were 

 harvested by removing infested leaves from the cages. 

 Then a rough count of adult predators was made, after 



12 



Fruit Notes, Winter, 1990 



