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Subject

Grape Whitefly

Description

Grape whitefly nymphs and pupae.

Grape whitefly, Trialeurodes vittatas (Quaintance) [Homoptera: Aleyrodidae], is a sporadic pest of commercial grapes. The species, native to California and found in both the coastal and interior valley regions, infests commercially planted grapes and native host plants in Butte, Lake, Los Angeles, Marin, Mendocino, Napa, Santa Barbara, Santa Clara, Santa Cruz, Sonoma, and Yuba counties.

Grape whitefly normally appears when the vineyard is close to chaparral or ornamental shrubs that are suitable as overwintering hosts. The only known evergreen host shrub is the coffeeberry, Rhamnus californica Eschscholtz, native to southwest Oregon, California, Arizona, and New Mexico. It is a dark green shrub, commonly 1 to 3 m (3 to 10 feet) high, with a green berry that turns red and finally black when ripe. Species of Crataegus, deciduous hawthorn, are known as the pest's summer hosts. other deciduous hosts are Vitis vinifera L., European grapes, and Vitis spp., American grapes.

Injury on commercial grapes is chiefly caused by sticky excrement soiling fruit. A black, sooty fungus develops on both fruit and foliage, causing serious smutting. Under high-population pressures, foliage and fruit turn black. This can cause major problems at harvest, and heavy insect-feeding pressure over time may also adversely affect the grapevine itself.

Publications

Blodgett S. 1992. Grape Whitefly. Pages 245-246 in: Grape Pest Management, 2nd edition. University of California Division of Agriculture and Natural Resources Publication 3343, Oakland, CA.

This website is a work in progress of the University of California (UC) Division of Agricultural and Natural Resources (ANR) Integrated Grape Production Workgroup. It is designed to increase accessability to the work of UC researchers, including faculty, Cooperative Extension (CE) specialists, CE advisors, and staff. UC Researchers interested in contributing content are invited to contact Deborah Golino dagolino@ucdavis.edu to discuss possible contributions.