Table 2. Abundance of T. pyri, A. fallacis, and European red mites (ERM) on leaves sampled in July, 

 August, and September in 1997 from first-level and third-level IPM blocks. 



* Each value represents the average number of individuals found on 55 leaves per block per sampling 

 date (25 leaves from the center tree and a total of 30 leaves from four other trees in the blocks, all of 

 which were four trees removed from the center tree). For each tree size at each time of sampling, 

 numbers followed by a different letter are significantly different at odds of 19:1. 



pyri. The fact that they were not used in third- 

 level blocks undoubtedly aided in establishment 

 of T. pyri. None of the acaricides used in either 

 first-level or third-level blocks is known to 

 affect T. pyri substantially. As hoped, none of 

 the third-level blocks received any Manzate, 

 Dithane, Mancozeb, or Penncozeb as fungicides, 

 whereas first-level IPM blocks received 

 substantial amounts of these materials up to 

 mid-June. Third-level IPM blocks did, 

 however, receive some Polyram before bloom 

 and a small amount after bloom. Some data 

 indicate that Polyram is just as harmful to T. 

 pyri as the other four aforementioned EBDC 

 fungicides, which are especially harmful when 

 applied during or after bloom. In general, the 

 profile of fungicides applied in third-leve) IPM 



blocks was quite (although not completely) 

 conducive to establishment of T. pyri. 



Conclusions 



The data presented here show convincingly 

 that T. pyri became established on trees in 

 which they were released: the centermost trees 

 in third-level IPM blocks of small, medium, and 

 large trees. Growers participating in this 

 experiment cooperated with its aims by not 

 applying harmful insecticides or acaricides and 

 by minimizing use of fungicides harmful to T. 

 pyri in the blocks in which T. pyri were 

 released. Interestingly, even more than three 

 months after release, T. /?>//■/ failed to move (in 

 detectable numbers) even as far as four trees 



12 



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



