Table 6. Foliar insect pest average population levels in second-level and first-level blocks in 1994.* 



♦Means in each couplet in each column followed by a different letter are significantly different at odds 

 of 19:1. PLH = potato leafhopper; WALH = white apple leafhopper; RLH = rose leafhopper; ABLM 

 = apple blotch leafminer; ABLMP = leafminer parasitoids; GAA = green apple aphid; GAAP = green 

 apple aphid predators: cecidomyiids and syrphids; WAA = woolly apple aphid. PLH, WALH, and 

 RLH data are average percentages based on bi-weekly samples of 100 or 200 fruit cluster or terminal 

 leaves or 100 watersprouts. ABLM data are the average number of (second and third generation only) 

 mines per 100 leaves based on bi-weekly samples of 100 or 200 fruit cluster or terminal leaves. GAA, 

 GAAP, and WAA data are percentage watersprouts infested based on bi-weekly samples of 100 

 watersprouts. 



bers initially, and the grower chose to apply a summer oil. 

 Although there was no statistical difference, transitional 

 second-level blocks had greater numbers of phytoseiid 

 predators than any other type of block in 1994, and early 

 problem mite populations were brought under control by 

 predators by late summer (Table 5). Yellow mite popula- 

 tions in first-and second-level blocks were similar (2.1 vs. 

 4.1%) and also were similar to 1993 levels. Dormant and 

 summer oil applications were slightly lower in second-level 

 than in first-level blocks, as were non-oil miticide applica- 

 tions (Table 1). 



PLH levels were significantly greater in second-level 

 than in first-level blocks, a difference from 1993 when 

 levels in both block types were almost identical. Both 

 WALH and RLH populations were higher in second-level 

 than in first-level blocks, although not significantly. In 

 1994, levels of all three types of leafhoppers were similar in 

 transitional and full second-level blocks (Table 6). 



ABLM populations were higher in second-level than in 

 first-level blocks; mine levels were similar to those found in 

 1993 (Table 6). In general, the transitional second-level 

 blocks fared better than full second-level blocks in terms of 

 mine numbers, but corresponding differences in the two sets 

 of first-level blocks suggest that this may be specific to the 

 orchards chosen and not due to differences in IPM manage- 

 ment techniques. Parasitism rates in transitional second- 

 level blocks were the same as those in full second-level 



blocks (Table 6). 



Both GAA and aphid predator levels were greater in 

 first-level than in second-level blocks, although popula- 

 tions in both types of blocks were very similar (Table 6). 

 Predators provided good control of aphid populations in 

 both types of blocks. Woolly apple aphids were absent from 

 both types of blocks (Table 6). 



Conclusions 



With regard to full second-level IPM practices that 

 involve substitution of cultural, behavioral, and biological 

 control methods for insecticide use after early June, we 

 conclude the following after four years of implementation: 



( 1 ) Little buildup of codling moth or ieafroUer beyond the 

 level existing in nearby firsl-level blocks; 



(2) Noticeable buildup of lesser appleworm from 1991 to 

 1994; 



(3) Consistently slightly greater injury by apple maggot 

 flies in second-level blocks, especially in late-ripening 

 cultivars; 



(4) No buildup of pest mites under slightly reduced miti- 

 cide use but insufficient buildup of predatory mites to 

 permit truly substantial reduction in miticide use (prob- 

 ably as a consequence of negative effects of fungicide on 

 mite predators); 



Fruit Notes, Winter, 1995 



