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 22.9).
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.
Cultural Pest Control
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.
Biological Pest Control
More than 10 species of parasites have been recorded from omnivorous leafroller larvae. However, seldom does mortality from these parasites exceed 10 percent. Predators such as lacewings, minute pirate bugs and spiders feed on young omnivorous leafroller larvae. See Appendix J, Beneficial Insects, Mites, and Spiders.
Biorational Pest Control
Microbials
Microbial insecticides Success, SpinTor, and Entrust can be used which contain the active ingredient spinosad, which is derived from a naturally occurring soil dwelling bacterium called Saccharopolyspora spinosa.
Chemical Pest Control
Recommended chemicals include Altacor (rynaxypyr), Sevin (carbaryl), Intrepid (methoxyfenozide), Imidan (phosmet), and Delegate (spinetoram). Insecticides used for controlling grape omnivorous leafroller in vineyards are presented in Appendix K, Insecticides Registered for Use in Vineyards.
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.
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