What's eating my grape 'niagara'?

Grape 'Niagara' (a Vitis labrusca white table grape) is most seriously threatened by Japanese beetle adults skeletonising leaves, grape berry moth larvae in clusters, and spotted wing drosophila in ripe fruit. Deer browse canes heavily in winter. Downy and powdery mildew weaken growth but Japanese beetle defoliation is the headline pest in North America.

Leaves skeletonised between veins from mid-summer; severe defoliation weakens vines. Hand-pick in early morning; use row-cover exclusion on small vines; apply approved insecticide (carbaryl, pyrethroids) when beetles are numerous. Do NOT use pheromone bag-traps — they attract more beetles than they catch.

First-generation larvae web young berries together; later generations bore into berries causing rot and cluster drop. Use degree-day models to time Bt or spinosad sprays at egg-hatch. Remove bark debris where pupae overwinter. Pheromone mating-disruption in larger plantings.

Thin-skinned ripe berries collapse with internal maggots; secondary rot follows. Harvest promptly at maturity; apply spinosad or insect-proof mesh on small plots; remove damaged clusters.

Young shoots browsed in spring; canes and bark rubbed or stripped in autumn by bucks. 8-foot deer fence is the only reliable long-term solution; repellent sprays reduce browsing if re-applied after rain.