sugar. Performance of sugar/flour PTS in this interval was 

 slightly better than in the initial 6-week trial, yielding 45.7% 

 kill prior to re-treatment with sugar. After spheres received 

 sugar treatment, wooden PTS rebounded to 75.0% effective- 

 ness, again outperforming sugar/flour PTS (67.0% kill of 

 exposed AMF). Taken together, it is quite clear that sugar/ 

 flour PTS are prone to lose toxicity over time (particularly 

 under heavy rainfall), while wooden PTS can retain a high 

 level of toxicity for a longer period under relatively adverse 

 field conditions. 



Conclusions 



If we focus on field performance of this season's PTS 

 and gauge their promise only on the basis of monitoring sphere 

 captures and fruit damage, both wooden PTS and sugar/fiour 

 PTS appear to be highly effective in controlling AMF. In 

 fact, this is the first season in which any PTS has outper- 

 formed (numerically, though not statistically) sticky spheres 

 or insecticide sprays in an extended field trial. Although these 

 data are encouraging, we believe that they are also some- 

 what deceiving, given the statewide dearth of AMF this sea- 

 son. 



In this study, it is much more revealing to focus on the 

 field/laboratory aspect of residual toxicity, bearing in mind 

 that our goal is to develop a PTS that provides 80%-90% kill 

 of arriving AMF without manual re-treatment with feeding 

 stimulant. In this context, neither PTS type approached op- 

 timal efficacy. However, this smdy provided key informa- 



tion to aid in further development of PTS. It appears that as 

 the season progresses, wooden PTS fitted with sugar/wax 

 caps do not retain enough sugar to stimulate consistent fly 

 feeding after 4 to 5 inches of rainfall. After re-treatment with 

 sugar, wooden PTS return to their original toxicity. Sugar/ 

 flour PTS, on the other hand, appear to actually lose toxicant 

 under field conditions, meaning that the spheres are inher- 

 ently less effective against AMF in mid- to late-season (the 

 period of greatest AMF risk). 



Given these data, the focus of our research has shifted 

 markedly toward fiarther development of wooden PTS that 

 can endure a fijll northeastern growing season, fitted with 

 sugar/wax caps designed to be replaced once during the sea- 

 son (see following article). Overall, we are encouraged by 

 the results of this commercial-orchard field trial, and remain 

 optimistic about the potential of PTS technology for control 

 of AMF 



A ckn o wledgm en ts 



We are very grateful to the seven growers who allowed 

 us to deploy traps in their orchards: Dave Chandler, Aaron 

 and Dana Clark, Tony Lincoln, Wayne Rice, Dave Shearer, 

 Joe Sincuk, and Mo Tougas. Sugar/flour PTS were provided 

 by FruitSpheres Inc. in conjunction with Robert Behle of the 

 USDA NCAUR facility m Peoria, IL. This project was sup- 

 ported by state and federal 1PM funds, along with grants from 

 the Massachusetts Society for Promoting Agriculture and the 

 US EPA IR-4 Program. 



it it it it *k 



Fruit Notes, Volume 65, 2000 



49 



