Comparison of Avaunt versus Guthion 

 in Every-row versus Perimeter-row 

 Sprays Against Key Apple Insect Pests: 

 2001 Results 



Ronald Prokopy, Andrew Baj, John Clements, Arthur Tuttle, and Brad Chandler 

 Department of Entomology, University of Massachusetts 



Organophosphate insecticides such as 

 azinphosmethyl and phosmet have been the mainstay 

 of grower control of plum curculios (PCs) and apple 

 maggot flies (AMF) for more than three decades. 

 Recent decisions by the EPA restrict use of these and 

 other organophosphates on apple trees in ways that may 

 cause growers to seek alternative approaches to 

 controlling these key apple pests. 



One possible alternative is substitution of one or 

 more newly-labeled compounds for organophosphates. 

 Another complementary approach is to reduce higher 

 costs associated with adoption of newly labeled 

 compounds by directing spray application only onto 

 perimeter rows of apple trees, leaving the bulk of 

 interior trees unsprayed. Previous research conducted 

 by ourselves and others using azinphosmethyl applied 

 only to perimeter rows of apple trees showed much 

 promise for effective season-long control of PC and 

 AMF. But this approach has not yet been evaluated 

 using any of the newly-labeled compounds for control 

 of PC, AMF and other important insect pests of apple. 

 The rationale underlying such an approach centers upon 

 two facts. First, nearly all PCs and AMF that invade 

 orchards originate from host trees and overwintering 

 sites outside of orchards. Second, immigrant PC and 

 AMF focus their attack first on perimeter rows of apple 

 trees before invading interior rows. 



In 2001, we initiated a four-year study aimed, 

 during the first two years, at comparing effects of 

 indoxacarb (Avaunt) versus azinphosmethyl (Guthion) 

 when applied to all rows versus only perimeter rows 

 of apple trees for control of PC, AMF, and other apple 

 insect pests. 



Materials & Methods 



In April of 2001, four plots were established in 

 each of six commercial apple orchards in 

 Massachusetts (24 plots in all). Rootstocks and 

 cultivars varied among orchards, but all trees in a given 

 orchard were on the same rootstock (either M.7, M.26, 

 or M.9) and of the same cultivar (either Mcintosh, 

 Empire, Cortland, Gala, or Delicious). Each plot was 

 about 40 X 40 yards in size and consisted of seven rows 

 of apple trees. The perimeter row bordered woods, 

 hedgerow, or open field and was subjected to pressure 

 from immigrating PCs and AMF. 



Growers themselves sprayed all rows of all plots 

 with azinphosmethyl or phosmet through petal fall. 

 Thereafter, all sprays were applied by a hired 

 experienced applicator using our newly purchased 

 tractor-mounted mist blower (which was not yet 

 available at the time of petal fall). Plots in each orchard 

 received four sprays after the petal-fall spray: 10 days 

 and again in 20 days after petal fall against PC, and on 

 July 1 8 or 1 9 and again on August 8 or 9 against AMF. 

 Spray was delivered at the equivalent of 150 gallons 

 of water per acre. Guthion (50 wp) was applied at the 

 rate of 10 ounces of formulated material per 100 gallons 

 against PC and 8 ounces of formulated material per 

 100 gallons against AMF. Avaunt (30% WG) was 

 applied at the rate of 2 ounces of formulated material 

 per 100 gallons against both PC and AMF. 



After the petal-fall spray, plots designated as "all- 

 row" plots received insecticide applied to both sides 

 of trees on all seven rows, whereas plots designated as 

 "perimeter-row" plots received insecticide sprays 



14 



Fruit Notes, Volume 66, 2001 



