![]() Record results on a monitoring form ( example form-PDF). In cool growing regions with a long period between bud swell and shoot growth, monitoring may be needed over a 2- to 3-week period. On each vine examine 5 buds for damage (total 25 buds per location). Check 4 vines within each location for damaged buds (total 20 vines). Randomly select five locations in the vineyard to observe, concentrating on areas known to be chronically infested. During the day they hid under loose bark towards the base of the vine and come out to feed at night. In spring cutworms leave the soil and climb up the vines. Because cutworm infestations are clumped, many vines must be examined to detect an infestation. Cutworms can be monitored along with other pests following the procedures discussed in DELAYED-DORMANT AND BUDBREAK MONITORING ( wine/raisin grapes or table grapes). Damageīegin to monitor bud feeding by cutworms during bud swell in early spring. ![]() Spotted cutworms routinely remain under grapevine bark in all production areas. In the San Joaquin Valley variegated cutworm larvae do not return to the soil but rather move under the bark. In the North Coast, the variegated cutworm normally returns to the ground during the day but may also remain under the bark of the vine. Variegated cutworm is the predominant species in the San Joaquin Valley and North Coast, while spotted cutworm is predominant in the Central Coast counties. A hand lens is needed to detect these hairs. Of the cutworm species that attack grapes, brassy cutworm is the only one with hairs protruding from the compound eye area. Mature brassy cutworms are 1.0 to 1.2 inch (2.5–3 cm) long and are reddish or brassy in appearance. A row of dark or black triangular markings are found on each side of the dorsal body surface. Mature spotted cutworms are about 1.3 inch (3.5 cm) long and are a dull gray brown. Body color varies from pale gray to dark mottled brown intermixed with red and yellow dots along the dorsum. Mature variegated cutworm larvae are 1.5 to 2.0 inch (3.8–5 cm) long with smooth skin. Positive identification is important as behavioral differences affect control actions. Cutworms are inconspicuously marked, dull-colored caterpillars ranging from 0.6 to 2.0 inch (1.5–5 cm) in length.
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