Grape producers in Georgia and Alabama need to be on alert: Japanese beetles are starting to show up in vineyards. According to the University of Georgia Extension Viticulture Blog, if there is a severe infestation, the Japanese beetles can be severe pests of grapes this summer, feeding mostly on the foliage.
What’s of most concern is their impact on young vines. Unlike older, more established vines that can withstand some feeding damage, younger vines can become defoliated.
The beetles are most active on warm, sunny days, which has been the case this spring and first part of the summer. There are no thresholds for leaf damage, but management is recommended when damage reaches below the top trellis wire or about 15% of the leaves are damaged.
UGA Extension advises growers to use their judgement and experience to determine if beetle activity warrants chemical control. Infestations are often highest near the borders of the vineyards. Focused management may be an option to minimize costs.
Management recommendations can be found at smallfruits.org: