approach to monitoring PC's in a small block of apple 

 trees in Clarkdale Fruit Farm in Deerfield. 



Materials & Methods 



The entire study was conducted along a 125-yard 

 section of perimeter-row apple trees bordered by 

 woods. The trees were mixed cultivars on M.26 

 rootstock. On May 2 (mid-pmk), every sixth tree was 

 baited with two dispensers of grandisoic acid (each 

 releasing about 1 mg per day) and eight dispensers of 

 benzaldehyde (each releasing about 10 mg per day). 

 All dispensers were replaced with fresh ones on May 

 30. 



One week after petal fall and weekly for 4 more 

 weeks, 20 fruit were examined on each of the five trap 

 trees and on each of four unbaited trees midway 

 between trap trees. Fruit were counted as injured if a 

 PC egglaying scar was evident. The trees received two 

 applications of insecticide to control PC without use 

 of fi-uit sampling information in guiding timing of spray. 



Results 



Figure 1 shows that fruit injury on the baited-trees 

 averaged about eight times greater than on unbaited 

 trees for samples taken at weeks 1 and 2 after petal fall 

 and about five times greater than on unbaited trees for 



samples taken at weeks 3, 4, and 5 after petal fall. As 

 the PC season progressed, some of the injured fi-uit on 

 both types of trees fell to the ground, but total injury 

 remained the same or increased owing to appearance 

 of fresh injury. 



Conclusions 



The results of this preliminary test are very 

 encouraging in that baiting perimeter-row trees with 

 attractive odor acted to concentrate immigrating PC's 

 on the "trap trees." Further research is necessary to 

 optimize the composition and amount of attractive odor 

 before this approach can be recommended for 

 widespread use in monitoring PC's in commercial 

 orchards. Conceivably, a few odor-baited "trap trees" 

 along perimeter rows of an orchard might serve not 

 only as focal trees for monitoring extent of fresh injury 

 caused by PC but, if sufficiently attractive, might also 

 serve to aggregate enough of the immigrating PC 

 population to permit spraying only trap trees, allowing 

 other trees to remain unsprayed against PC. 



Ackno wledgm ents 



Thanks to Tom Clark for cooperating in this 

 experiment, and Jaime Pifiero for preparing the figure. 



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24 



Fruit Notes, Volume 67, Winter, 2002 



