Chapter 21

Managing Vineyard Insect and Mite Pests

Grape Berry Moth

Grape berry moth (Endopiza viteana) is a major insect pest causing serious economic loss to commercial vineyards. The insect is native to eastern North America where it coevolved with wild grapes; its range has now extended west to the Rocky Mountains wherever wild or cultivated grapes occur.

Symptoms

Damage results from first generation larvae feeding on flower clusters or small berries, leaving silken strands where they have crawled (See Figure 21.3). Webbing can be dense, encasing blossoms, stems and entire sections of fruit clusters. The second generation larvae burrow into the grape berry and feed internally, which can be more damaging than the first generation.

Life Cycle

Grape berry moths overwinter in cocoons within folded leaves and debris on the vineyard floor, and within adjacent woodlots, especially where grapevines are found. The fallen grape leaves frequently are blown out of the vineyard during winter winds and may concentrate in fence rows and areas with brush near the vineyard. For this reason, berry moth infestation is often more severe on the edge of vineyards near these areas.

Monitoring

Infestations of grape berry moth can vary greatly from year to year and within a vineyard. Pheromone traps can be used to monitor the timing of the first adult berry moth emergence. Strategically place pheromone traps before bloom in vineyard border rows near suspected over-wintering areas—adjacent woodlands, particularly where native grapes are present.

Pest Management

Cultural Practices

Eliminating leaves on the vineyard floor as well as in woodlands and wasteland areas near vineyards will help in minimizing the number of overwintering pupae in leaves. Some degree of grape berry moth control is possible by burning or burying the leaves where pupae over-winter.

Applying Control Materials

It is important to apply control sprays just prior to egg laying (oviposition) and up until the larvae enter young berries. A large population of grape berry moth in the traps and significant damage to flower clusters or very young fruit (e.g., 5% larval damage to grape clusters) indicates the need for early insecticide application. If an insecticide spray is warranted, the first application should be made five days after the first moth was captured. This application will also give control of a large number of minor pests that sometimes infest grapes.

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