Insecticidal Soap for Pear Psylla 

 Management 



William M. Coli and Craig S. Hollingsworth 



Department of Entomology, University of Massachusetts 



Anthony Rossi 



Department of Plant & Soil Sciences, University of Massachusetts 



We reported in an earlier article [Fruit Notes 

 53(2): 13- 15] on a comparison between Safer's™ insec- 

 ticidal soap and amitraz applied by hydraulic handgun 

 as summer sprays against pear psylla. Results of that 

 study indicated that: 1) both the soap and amitraz 

 caused a significant reduction in active stages of psylla; 

 2) soap caused the formation of dark surface lesions on 

 49% of the pears; and 3) soap treatments were 37% 

 more costly than amitraz. However, these initial re- 

 sults were sufficiently promising, especially consider- 

 ing the desirability of developing alternate strategies 

 for psylla management, that we continued our investi- 

 gations of insecticidal soap as a tool for managing pear 

 psylla and various apple pests. In this article we report 



on the results of our 1989 trials in pear. 



Treatments were applied to two rows of 15 Bartlett 

 trees at the Horticultural Research Center (HRC), 

 Belchertown, MA. To more closely approximate the 

 application conditions in commercial orchards, all 

 chemical applications were made to run-off with a 

 Bean 400-gal speed sprayer at 300 psi with a delivery 

 rate of 50 gal./acre. 



In both rows, oil at 1 gal/ 1 00 gals water was applied 

 on April Hand 25. Polyram™80 WPat 1 to 1.51bs/100 

 gal was applied on April 14 and 25, May 23, June 5 and 

 27, July 17 and 24, and August 9. Guthion™ 35 WP at 

 0.63 lbs/100 gals was applied at petal fall (May 23). 



In the standard program block, Imidan™ 50 WP at 



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May23June1 7 14 21 29 July 6 12 18 24 31 Aug 7 14 21 24 25 



Figure 1 . The average number of all pear psylla nymphs per terminal throughout the 1989 growing season. 



26 



Fruit Notes, Spring, 1990 



