Figure 3. In July and August of 1998, abundance of European red mites on leaves sampled from tfiird- 

 level IPfVI blocks (in which 7". pyri were released on the center tree in mid-May 1997) and first-level IPfvl 

 blocks (in which no releases of r pyn were made). 



Third-Level IPM Blocks. Low Tree Density 



^V 



^/^-^ 



Sample Date 



Legend: 



First-Level IPM Blocks. Low Tree Density 



Sample Date 



First-Level IPM Blocks. High Tree Density 



1- 5 



Sample Date 



Center Tree 



Center Row, Outer Trees 



Outer Row. Center Trees 



Results in third-level IPM blocks in 1997. Populations on 



center trees in early July averaged greatest on small 



As shown in Figure 1, T. pyri were found in (high density) trees, middle range on middle-size 



low but detectable average numbers in early July (middle density) trees, and least on large (low den- 



of 1998 on center trees in which they were released sity) trees. By the latter part of August, T. pyri on 



Fruit Notes, Volume 64 (Number 1), Winter, 1999 



13 



