Project Number: 6606-21000-002-23
Project Type: Reimbursable

Start Date: Nov 01, 2006
End Date: May 31, 2009

Objective:
Current management of peachtree borer (Synanthedon exitiosa [Lepidoptera:Sesiidae]) attacking peach relies on handgun application of chlorpyrifos to trunks. However, no efficacious management strategy exists for the lesser peachtree borer (Synanthedon pictipes [Lepidoptera:Sesiidae]). This once secondary pest recently has become an aggressive, tree-killing primary peach pest. Regulatory-induced removal of certain organophosphates from peach production has exacerbated the pest status of the lesser peachtre borer to the point of seriously impeding peach production in the southeastern U.S. A conventional management program against the lesser peachtree borer would necessitate a very rigorous in-season regime of labeled organophosphates (at higher rates than needed for other pests), plus the addition of 2 more post-harvest applications of chlorpyrifos under Section 24C labels in the SE states. However, given the current lack of efficacy for these applications (in addition to the economic, worker safety and environmental concerns that would come with such a program) alternatives for borer management are sorely needed. Here we propose to implement biological control of both peachtree borer and lesser peachtree borer in orchards by using entomopathogenic nematodes. Given the level of control we have already achieved in field and laboratory trials using entomopathogenic nematodes, the probability of successfully implementing this reduced risk alternative to organophosphates is high.

Approach:
Two species of Sesiidae (Lepidoptera) attack and seriously damage peach across the eastern U.S. In the southeastern U.S., management of the peachtree borer, Synanthedon exitiosa, entails a single post-harvest application of the organophosphate insecticide chlorpyrifos to trunks. Although very effective against the single generation of the peachtree borer (PTB), worker safety and environmental stewardship issues compromise this approach. Additionally, peach industry leadership in the Southeast is eager for biologically-based management options, as they must deal with the bulk of exposure to pesticides, and the marketing negatives of perceived consumer risks due to use of any broad spectrum insecticide, even during post-harvest periods. The other sesiid species is the lesser peachtree borer, Synanthedon pictipes. Until recently, the lesser peachtree borer (LPTB) was a minor, secondary pest of older, declining orchards, but has become an aggressive, tree-killing primary peach pest in the southeastern U.S. Regulatory-induced removal of certain organophosphates appear responsible for elevation of LPTB to its current major pest status. The lesser peachtree borer (LPTB) has multiple generations in the Southeast. This renders an insecticidal approach ineffective because chlorpyrifos, the most effective insecticide, cannot be applied to fruit (i.e., from March through harvest [early May to early August depending upon the variety]), even though LPTB is ever present. As a stop-gap nonetheless, many GA and SC growers are using multiple applications of post-harvest applied chlorpyrifos as authorized by 24C labels. There is no doubt that Southeastern peach production, worker safety and environmental stewardship all would benefit from implementation of reduced-risk alternative strategies for sesiid borer management. We propose that entomopathogenic nematodes (EPNs) can be a viable part of such a strategy.