11 



trees; and (3) to accurately relate the numbers of TPB sampled by 

 this method to the amount of TPB injury. We hoped we could eventually 

 construct an index or chart which would indicate to the grower that 

 if X number of TPB adults were taken in the samples, then X amount 

 of TPB injury could be expected. Based upon the intended market for 

 the fruit, and therefore the amount of TPB injury the grower felt he 

 could tolerate, the grower could then decide if it was worthwhile to 

 spray a pesticide against TPBs. In this article, we report on our 

 progress to date toward these goals. 



To study the nature an 

 structed a large number of 

 unsprayed section of orchar 

 each cage was positioned to 

 buds on a branch. We intro 

 and sealed the ends to prev 

 12, 1977, the day the first 

 buds were at green tip. Th 

 after which they were remov 

 further entry of insects, 

 new cages every 4-5 days un 

 days at bloom for pollinati 

 correlate the stage at whic 

 to TPBs with the nature and 



d occurrence of TPB injury, we first con- 

 cages made of plastic and cloth. In an 

 d at the Horticultural Research Center, 



completely surround 6-7 developing flower 

 duced one TPB adult into each of 6 cages 

 ent escape. The cagings began on April 



TPB adult was found in the orchard. The 

 e TPBs remained in the cages for 4 days, 

 ed and the cages resealed to prevent 

 We repeated this procedure with TPBs in 

 til July 1 (the cages were opened for 4 

 on). Using this procedure, we could 

 h developing apple flower buds were exposed 



amount of ensuing injury. 



The data in Table 1 reveal that feeding by caged TPBs on apple 

 flower buds at the green tip and half inch green stages caused a 

 substantial amount of bud abscission. No detectable bud abscission 

 resulted from TPB feeding initiated at tight cluster or afterward. 



TABLE 1 



Time of initiation of 

 injury by TPB adults 

 in cages 



Average number of 

 flowers per cluster 

 at full bloom 



% decrease 

 compared with 

 check 



Green tip 



Half inch green 



Tight cluster onward 



Check (cages without TPBs) 



3.1 

 3.7 

 4.5 

 4.5 



311 



18°^ 



0% 



Most years abscission resulting from early season TPB feeding 

 would not be an important economic consideration. However, in off- 

 bearing years, years of severe frost damage, or poor pollination, 

 this bud abscission could be important. 



The data in Table 2 reveal that feeding by caged TPBs on buds, 

 blossoms, and fruit from mid-pink to petal fall caused dimples in a 



