Treatment is justified when about 10 to 15% of buds in susceptible areas are damaged. Check three vines within each location for buds damaged by cutworms (total of 60 vines). Concentrate on areas with a history of cutworm damage. Monitoring should start during bud swell for the presence of bud feeding/injury by cutworms. Cutworm infestations usually are localized within vineyards and often occur in the same places each year. Sampling and thresholds Cutworm control decisions usually are based on levels of bud injury in early spring. There are one or more generations per year. Moths emerge from the soil in May and June. Mature larvae return to the soil to pupate. Recent research indicates that most damage to grapevine buds is caused by the two climbing cutworm species, Abagrotis orbis and Agrotis vetusta. If broad-leaved weeds are available, many cutworm species will stay on the vineyard floor. Not all cutworm species in vineyards will climb grapevines. They remain under cover during the day (in cracks in the soil, plant debris, or under rough bark on the trunk), and climb vines at night to feed on buds and shoots. Cutworms begin feeding on winter annual weeds during warm periods in February to March. Spotted cutworms have a row of dark, elongated triangular markings on each side of the upper body surface.īiology and life history The spotted cutworm overwinters in the soil or under debris as a partially grown second or third instar. Caterpillars of these moths (cutworms) grow to about 1.5 inches long and are generally a dull gray-brown. Adults are dark gray moths about 1 inch long, and wingspan is about 1.5 inches.

Depending on variety, the fruitfulness of secondary shoots is often lower than primary shoots, leading to reduced yields. When primary buds/shoots are destroyed, secondary buds may emerge. The larvae feed on developing buds and emerging young shoots. Cutworm larvae injure grapes primarily in early spring at or shortly after budbreak. Pest description and crop damage Only the surviving overwintering cutworm larval population causes damage to grapevines. Climbing cutworm ( Abagrotis orbis and Agrotis vetusta)įor more information about winter cutworm, and photos and descriptions of the other cutworms, please refer to the publication 'Winter Cutworm: A New Pest Threat in Oregon' (.

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