Evaluation of Two Consecutive Years of Mating Disruption for Control of Greater Peachtree Borer (Synanthedon exitiosa) in Peaches

Diane G. Alston and Carin A. Miller

Department of Biology, Utah State University

Objective: To evaluate and demonstrate the efficacy of mating disruption with Isomate-P for control of greater peachtree borer in peaches for two years.

The greater peachtree borer (GPTB) is an important pest of peach, apricot, nectarine and sweet cherry. Damage is caused by the larvae, which burrow beneath the bark of the trunk near or just below the soil surface. Larvae feed on the cambium beneath the bark and can girdle trees, thus, killing them. The standard treatment to prevent damage by GPTB in commercial orchards is application of an insecticide to the trunk of susceptible trees during early July, and sometimes a second application one month later. A potential non-pesticide alternative is pheromone-based mating disruption. Mating disruption (MD) was used for GPTB control in two peach orchards (blocks identified as MD-1 and MD-2) during summer of 2000 at the USU Kaysville Agriculture Experiment Station (Davis Co., UT). The same two blocks plus a new peach block (MD-3) received mating disruption treatment in 2001.

Methods: Isomate-P (rope-style) dispensers from Biocontrol Limited (Vancouver, WA 98660, 1-800-999-8805) were applied to two peach orchards in 2000 (MD-1, 1 acre ‘Suncrest’ planted in 1990; MD-2, 1 acre ‘Red Haven’ planted in 1994) and to the same two orchards plus a new orchard (MD-3, 0.9 acre ‘Red Haven’ planted in 2001) in 2001. The dispensers were applied at a rate of one per tree, which resulted in 155-175 dispensers per acre. The recommended dispenser application rate is 100-250 dispensers per acre. The Isomate-P dispensers were applied on 21 June in 2000 and 22 June in 2001, within four days of the first capture of GPTB moth in one of the orchards. The same insecticide-treated comparison block was used in both years (Kaysville Treated, 1.5 acre mixed cultivars (‘Gleason Elberta’, ‘Red Globe’, ‘Cresthaven’)). The insecticide comparison block was treated with a single application of Lorsban (chlorpyrifos) in early July in both years. One wing-style pheromone trap was placed in each block in each year to monitor moth abundance. Every tree trunk in each block was evaluated for GPTB injury on 20 September 2000 and 3 October 2001 by visual inspection of the lower trunk and removal of approximately 1 inch of soil around each tree base.

Results: No GPTB moths were captured in mating disruption blocks after the Isomate-P dispensers were applied (Figs. 1 and 2). In contrast, GPTB moths were captured in the Kaysville insecticide-treated and Genola (Utah Co., UT) comparison block (Genola Reference) from late June through mid August in 2000 and through mid September in 2001. GPTB moth densities were approximately two times greater in 2000 than in 2001. No GPTB injury was detected in any block in either year. It appears that mating disruption can provide highly successful control of GPTB, comparable to a standard insecticide program.