29 



Table 3. Mean abundance of pest and predaceous arthropods at peak 



sample populations on foliage in Previous-Year IPM, First-Year IPM, 

 and Check blocks, 1982. 



Species^ 



Mean abundance/Sample unit' 



European red mite 

 Two spotted mite 

 A. f allacis 

 Green aphids 

 A. aphidimyza 

 Syrphid spp. 



Leafminers' 



Sample unit = Individual leaves for mites and leafminers, and foliar 

 terminals for aphids and aphid predators. 



^In 1982, mite sampling was performed near "hot spots" when initial 

 leaf bronzing or numerous active mites were noticed. In check blocks, 

 trees were sampled randomly. 



■'^First generation mine counts in 21 previous and 9 new IPM blocks; 2nd 

 generation mine counts in 20 previous and 11 new IPM blocks; 3rd gen- 

 eration mine counts in -23 previous and 12 new blocks. 



the fruit calyx in significant numbers in 2 blocks. Amblyseius 

 fallacis , our major predatory mite, was present in low numbers in 

 1982, a phenomenon reported by other Northeast and Canadian tree fruit 

 entomologists. A. fallacis was first observed on August 4, after 

 red mite and two spotted mite populations had reached treatment levels 

 at several sites. A. fallacis was ultimately found in 211 of IPM 

 blocks, but the highest recorded sample had only 0.3 predators per 

 leaf. IPM blocks averaged 0.03 A. fallacis per leaf compared to 0.01 

 per leaf in the checks. 



We are not able to explain why predator mite numbers were low in 

 1982 (down from an' average of 0.2 per leaf in 1981). However, 

 A. fallacis appeared too late and in too few numbers to affect red 

 and two spotted mite numbers in monitored orchards. 



Insecticide, aphicide 



and miticide use , 

 blocks (average 6 



Previous-Year IPM blocks (average 6.3 insecticide sprays, range 

 4 to 10) and First-Year IPM blocks (average 7.0 insecticide sprays. 



