Entomopathogenic Nematodes as an Alternative Management Strategy for Grape Root Borer
Applied Research
Clark Macallister
County Extension Coordinator
University of Georgia
Dawsonville
Abstract
Grape root borer (GRB) is a native pest that attacks both cultivated and wild grape vines. GRB larvae spend nearly two years underground feeding, subsequently damaging vines by girdling the roots. Injury due to GRB larvae often goes unnoticed until it is too late, leading to a reduction in winter survival and fruit quality, and even vine death. Chlorpyrifos, the main insecticide labeled for use against GRB, was banned in 2022, and as such effective curative treatments for GRB control are limited. Previous research has shown that entomopathogenic nematodes (EPN) can effectively reduce GRB in grape production. During the 2020 and 2021 growing seasons, two EPN strains, Steinernema feltiae (Sf) and Heterorhabditis bacteriophora (Hb), were evaluated at commercial wine grape vineyards in north Georgia (two sites in 2020, and four sites in 2021). Pheromone-baited bucket traps were used to monitor adult GRB flight, and soil beneath the vines was examined for presence of exuviae (pupal casings). During both years, adult GRB moths were active from mid-July to early September, but substantially more moths were collected in 2020 than 2021. In terms of GRB emergence, both the Hb and Sf treatments had fewer exuviae than control vines, with Hb treatments performing the best. Similarly, when evaluating GRB management at all four vineyard sites, Hb treated vines had significantly fewer exuviae than control vines, whereas Sf had only marginally fewer exuviae than control vines. Evidence that the EPNs, particularly Hb, may reduce GRB infestation is encouraging and warrants further research.
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Authors: Clark Macallister, Nathan Eason
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Macallister, C. County Extension Coordinator, UGA Extension, Georgia, 30534
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Eason, N. Agriculture and Natural Resources Agent, UGA Extension, Georgia, 30528