title: Curative Control of the Peachtree Borer Using Entomopathogenic Nematodes.
abstract: The peachtree borer,Synanthedon exitiosa(Say 1823), is a major pest of stone fruit trees in North America. Current management relies upon preventative control using broad-spectrum chemical insecticides, primarily chlorpyrifos, applied in the late summer or early fall. However, due to missed applications, poor application timing, or other factors, high levels ofS. exitiosainfestation may still occur and persist through the following spring. Curative treatments applied in the spring to established infestations would limit damage to the tree and prevent the next generation ofS. exitiosafrom emerging within the orchard. However, such curative measures for control ofS. exitiosado not exist. Our objective was to measure the efficacy of the entomopathogenic nematode,Steinernema carpocapsae, as a curative control for existing infestations ofS. exitiosa. In peach orchards, spring applications ofS. carpocapsae(obtained from a commercial source) were made to infested trees and compared with chlorpyrifos and a water-only control in 2014 and 2015. Additionally, types of spray equipment were compared: nematodes were applied via boom sprayer, handgun, or trunk sprayer. To control for effects of application method or nematode source, in vivo laboratory-grownS. carpocapsae,applied using a watering can, was also included. Treatment effects were assessed 39 d (2014) or 19 d (2015) later by measuring percentage of trees still infested, and also number of survivingS. exitiosalarvae per tree. Results indicated thatS. carpocapsaeprovided significant curative control (e.g., >80% corrected control for the handgun application). In contrast, chlorpyrifos failed to reduceS. exitiosainfestations or number of surviving larvae. In most comparisons, no effect of nematode application method was detected; in one assessment, only the handgun and watering can methods reduced infestation. In conclusion, our study indicates thatS. carpocapsaemay be used as an effective curative measure forS. exitiosainfestations.
authors.affiliation: USDA-ARS, Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008.
authors.forename: David I
authors.initials: DI
authors.lastname: Shapiro-Ilan
authors.affiliation: USDA-ARS, Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008.
authors.forename: Ted E
authors.initials: TE
authors.lastname: Cottrell
authors.affiliation: Department of Entomology, NFREC, University of Florida, Quincy, FL.
authors.forename: Russell F
authors.initials: RF
authors.lastname: Mizell
authors.affiliation: Department of Entomology, University of Georgia, Athens, GA.
authors.forename: Dan L
authors.initials: DL
authors.lastname: Horton
keywords: Steinernema carpocapsae; Synanthedon exitiosa; application method; curative; entomopathogenic nematode; peachtree borer