Chapter 21

Managing Vineyard Insect and Mite Pests

Grape Omnivorous Leafroller

Grape leafrollers (Platynota stultana) are common pests of grapevines. They have also been reported in Illinois, Massachusetts, Michigan, Virginia, Florida, Texas, Arizona, and California. 

Symptoms

Damage to leaves by omnivorous leafrollers occurs when the larvae chew holes through the leaves or feed on upper or lower leaf surfaces, causing brown spots (See Figure 21.9).

Life Cycle

Omnivorous leafroller overwinters in the larval stage in grape mummies, vineyard weeds, and other debris in the vineyard.

Monitoring

Omnivorous leafroller larvae are often confused with grape leaffolders. Omnivorous leafrollers can have either a black or brown head capsule, depending on the instar. Mature larvae range in color from cream to brownish green with whitish slightly convex tubercles on the top of the abdomen.

Pest Management

Cultural Practices

During the dormant season remove mummy clusters and control vineyard weeds. Destroy old clusters that fall on the berm or end up in the middles after pruning.

Applying Control Materials

Treat for leafroller at bloom if the vineyard has a history of this pest or if a serious infestation occurred in the previous season. Bloom is the preferred timing for sprays because the limited foliage and open clusters allow for better coverage. Otherwise, monitor to determine the need for treatment. Later in the season populations are more difficult to control because the greater leaf canopy and larger berries make it harder to get adequate insecticide coverage inside the clusters.

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