Commercial Orchard Evaluation of 

 Pesticide-treated Spheres for Apple 

 Maggot Control in 2001 



Ronald Prokopy, Bradley Chandler, Sara Dynok, Paul Appleton, 



and Steven Becker 



Department of Entomology, University of Massachusetts 



In the 2000 issue of Fruit Notes, we described 

 results of year-2000 orchard trials of pesticide-treated 

 spheres (PTS) for controlling apple maggot flies 

 (AMF). These trials involved evaluation of 

 biodegradable sugar/flour PTS as well as wooden PTS 

 topped with a disc composed of sugar and wax. We 

 found that neither type of PTS approached optimal 

 efficacy. Sugar/flour PTS suffered progressive loss of 

 toxicant under rainfall as well as progressive loss of 

 sphere integrity due to consumption of spheres by 

 rodents and other mammals. Wooden PTS maintained 

 a high level of residual toxicant throughout the summer 

 of 2000, but the top caps did not retain enough sugar 

 to stimulate consistent feeding of AMF on the sphere 

 surface after 4-5 inches of rainfall and, like sugar/flour 

 spheres, were vulnerable to consumption by rodents 

 and other mammals. 



In the preceding article in this issue of Fruit Notes, 

 we describe recent laboratory research that gave rise 

 to an improved type of sugar/wax disc for placement 

 atop a wooden PTS. Here, we describe commercial 

 orchard trials conducted in 2001 comparing the 

 effectiveness of wooden PTS topped by improved 

 sugar/wax discs with the effectiveness of standard 

 sugar/flour PTS and sticky-coated spheres for 

 controlling AMF. 



Materials & Methods 



The improved sugar/wax discs had the following 

 properties: a size of 2 inches diameter by 3/4 inch tall; 

 a composition of 85% sucrose and 15% paraffin wax 

 (50 grams total mass); a top surface into which eight 

 shallow reservoirs were pressed to permit retention of 

 a small amount of water that could percolate through 

 the slightly porous body of the disc; a hardness that 



resulted from compression under 20 tons of hydraulic 

 pressure; and an embedded wire guard surrounding the 

 disc to protect it from consumption by rodents. Red 

 vegetable dye was mixed with the sucrose to color each 

 disc red. The dye was absorbed by the sugar. As the 

 amount of sugar diminished under rainfall or dew, so 

 also did the color of the disc change from red to pink 

 and eventually white. This allowed visual assessment 

 of the relative amount of sugar remaining in the disc. 

 A disc was positioned atop each 3 .25-inch wooden PTS 

 by unscrewing the metal shaft holding the sphere, 

 pushing the shaft through the small hole at the center 

 of the disc and then reattaching the shaft to the sphere. 

 The sphere received a coat of black latex paint 

 containing 4% (a. i.) imidacloprid (Provado). Water 

 containing 20% sucrose was sprayed on each wooden 

 PTS just before deployment. 



Sugar/flour spheres likewise were 3.25 inches 

 diameter, coated with black latex paint containing 4% 

 (a. 1.) imidacloprid (Provado) and were purchased from 

 FruitSphere Inc. (Peoria, Illinois). Except for 

 substitution of black for red latex paint and an increase 

 in amount of imidacloprid from 2 to 4% a. i., sugar/ 

 flour spheres were the same as those we evaluated in 

 orchard trials in 2000. 



Sticky spheres were 3.25 inches in diameter, red in 

 color, and coated with Tangletrap to capture alighting 

 AMF. 



Spheres were evaluated in six commercial orchards 

 in MA, each of which contained four small plots of 

 apple trees (~ 49 trees per plot). Three of the plots 

 received no insecticide after mid-June and were 

 surrounded by either wooden PTS, sugar/flour PTS, 

 or sticky spheres placed about 5 yards apart on 

 perimeter trees during the first week of July. Each 

 sphere was baited with a vial of butyl hexanoate. The 



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Fruit Notes, Volume 66, 2001 



