Is More Than One Trap Tree Required 

 on Perimeter Rows to IVIonitor the 

 Course of Plum Curculio Injury 

 to Fruit? 



Jaime Pinero, Isabel Jacome, Paul Appleton, Marina B. Blanco, and Ronald Prokopy 

 Department of Plant, Soil, and Insect Sciences, University of Massachusetts 



The concept of a trap tree as a practical approach 

 to determine need and timing of insecticide applications 

 against overwintered plum curculios (PCs), based on 

 the occurrence of fresh egglaying injury, was put 

 forward by Ron Prokopy in the 2002 Winter 

 Issue of Fruit Notes. Based on research 

 conducted during 2003, the following guidelines 

 were proposed: (1) use of four vials dispensing 

 benzaldehyde (BEN), the attractive host plant 

 odor at a rate of -40 mg/day (= 4 BEN), in 

 association with one dispenser releasing the 

 attractive PC pheronione grandisoic acid (GA) 

 at a rate of ~1 mg/day (= 1 GA); (2) use of a 

 threshold of one fruit showing fresh PC injury 

 out of 25 fruit sampled on a trap tree; and (3) 

 use of a single perimeter-row odor-baited tree 

 located mid-way of a perimeter row 

 encompassing 60-70 yards. 



Because in our 2003 evaluations the greatest 

 distance tested on a perimeter row was 30 yards 

 to either side of a trap tree, it was not possible 

 to determine whether trap trees would be 

 attractive to PCs over distances longer than 30 

 yards. Whether or not the amount of attractive 

 odor being emitted by a trap tree could draw PCs 

 into an orchard from a distance greater than they 

 would normally travel to find an orchard, which 

 could potentially result in a greater-than-normal 

 amount of PC injury to fruit on perimeter-row 

 trees having trap trees, was another question that 

 came out from the 2003 evaluations. 



Here, our objectives were to detennme (1) 

 the maximum distance over which the 

 combination of 4 BEN + 1 GA is able to 

 congregate PCs and (2) whether an increase in 



the number of odor-baited trees on a perimeter row is 

 associated with increasing amount of damage to 

 perimeter-row fruit. 



= Trap tree 



Figure 1 . Representation of an apple orchard block 

 having on each of its four sides either 0, 1 , 2, or 4 trap 

 trees spaced equidistantly. Each trap tree was baited 

 with 4 BEN and 1 GA. Each of the four sides of the 

 blocks used for this study comprised at least 120 

 yards. 



14 



Fruit Notes, Volume 69, Fall, 2004 



