Establishment and Spread of Released 

 Typhlodromus pyri Predator Mites in 

 Apple Orchard Blocks of Different Tree 

 Size: 1997 Results 



Ronald Prokopy, Starker Wright, and Jonathan Black 

 Department of Entomology, University of Massachusetts 



Jan Nyrop, Karen Wentworth, and Carol Herring 



Cornell University, NY Agricultural Expe?ime?it Station, Geneva 



Pest mites are usually completely controlled 

 by predatory mites on unmanaged apple trees 

 that receive no insecticide or fungicide. Some 

 commonly-used orchard pesticides (e.g., 

 synthetic pyrethroid insecticides, EBDC 

 fungicides) kill or otherwise harm predatory 

 mites, leading to pest mite outbreaks and need 

 for miticide application. In Massachusetts, the 

 predatory mite Amblyseius fallacis is present 

 in about 90% of commercial orchards (see 1994 

 Spring issue oi Fruit Notes) but usually not in 

 numbers sufficient for providing mite biocontrol 

 until August. Studies in New York have shown 

 that the predatory mite Typhlodromus pyri, 

 where established, can be an extremely 

 effective season-long biocontrol agent of pest 

 mites. This is a result of their ability to endure 

 cold winter temperatures and periods of short 

 supply of pest mites as food much better than^. 

 fallacis. Unfortunately, few Massachusetts 

 orchards appear to harbor significant natural 

 populations of T. pyri. 



In the 1997 Spring issue oi Fruit Notes, we 

 reported that when T. pyri obtained from 

 Geneva, New York were released in 1995 into 

 blocks of apple trees in six commercial orchards 

 in Massachusetts, they became established in 

 all blocks save those in one of the six orchards. 

 On average, after two years, they had built to 

 greater numbers in blocks managed under 

 second-level IPM practices (no pesticide of any 



type used after early June) than in blocks 

 managed under first-level IPM (sprayed with 

 fungicide and insecticide through summer). 

 These findings stimulated us to conduct 

 further research on the establishment oiT.pyri 

 released in Massachusetts apple orchards. 



We report here first-year results of a study 

 in which T.pyri were released in 1997 on single 

 trees in the center of blocks comprised of small, 

 medium, or large trees and managed under 

 third-level IPM practices. 



Materials & Methods 



Our experiment was conducted in six blocks 

 of apple trees in each of eight commercial 

 orchards. Of the six blocks per orchard, two 

 each contained trees on M.9, M.26, or M.7 

 rootstock, designated as small, medium-size, or 

 large trees. One block of each pair received 

 first-level IPM practices, wherein growers 

 applied insecticide and fungicide materials of 

 their own choosing and timing of application, 

 which extended from April through August. 

 The other block of each pair received third-level 

 IPM practices, wherein the intent was that no 

 synthetic pjrrethroid insecticide was to be used 

 at any time, use of EBDC fungicides was to be 

 minimized, no insecticide of any type was to be 

 used after mid June, and captan or benomyl 

 were the only fungicides to be used after mid 



Fruit Notes, Volume 62 (Number 4), Fall, 1997 



