Veraison, which is expected to be underway or even completed in many California wine and raisin grape vineyards by the end of June, is no time to ease up on monitoring for caterpillars and, some cases, treating to control them.
Keep ahead of any caterpillar threat with continued monitoring and treatment as needed
Grape leaffolder and western grapeleaf skeletonizer feed on foliage, and heavy populations can lead to defoliation. Omnivorous leafroller, orange tortrix, and light brown apple moth feed on leaves, flowers and developing berries. However, they damage grape crops primarily by feeding on fruit which enables rot organisms to enter the fruit at the damage sites.