The European grapevine moth infestation in September 2010 that
led to the quarantine of 93-square miles in South County is getting
more attention from the Santa Clara County Department of
Agriculture this week as an eradication plan will be carried out
near the intersection of Day Road and Watsonville Road. Three moths
were found last year – enough to cause a scare in the affected
neighborhoods.
The European grapevine moth infestation in September 2010 that led to the quarantine of 93-square miles in South County is getting more attention from the Santa Clara County Department of Agriculture this week as an eradication plan will be carried out near the intersection of Day Road and Watsonville Road. Three moths were found last year – enough to cause a scare in the affected neighborhoods.
The eradication effort will focus on “intensive trapping” in vineyards and backyard grapevine at about 90 properties with the treatment area, according to a county press release. Flower and fruit removal from grapevines is scheduled to begin in Gilroy as soon as next week. An informational open house to discuss the eradication program is scheduled for 5 to 7 p.m. Tuesday at the San Martin Lions Club, 12415 Murphy Ave.
The moths found in September near Watsonville Road, north of Day Road are third generation adult moths, which could become the most damaging version – as worms – if they become active in the springtime. Now and into the winter they will go dormant, but in the spring they will feed on ripening grapes and expose them to further damage through fungal infections. The moths can cause the grapes to brown and rot and can ruin an entire crop if they reproduce and spread.
The European grapevine moth larvae, not the adult moths, are responsible for the damage to grapes. Larvae (worms) emerge early in the spring and feed on grape bud clusters or flowers, according to the press release. The larvae then spin webbing around them before pupating inside the web or under a rolled leaf. If heavy flower damage occurs during this first generation, the affected flowers will fail to develop and yield will be reduced. Second-generation larvae chew into the grapes to feed before pupating in the clusters or in leaves. Larvae of the third generation, the most damaging generation, feed on multiple ripening grapes and expose them to further damage from fungal development and rot. These larvae through winter as pupae in protected areas such as under bark, and emerge as adults the following spring.
The California Department of Food and Agriculture’s first choice for treatment is flower and fruit removal from backyard grapevines within 500 meters of where European grapevine moth was found. If property owners prefer otherwise, the second choice is ground treatment with the organic compound “Bt,” or bacillus thuringiensis, a naturally-occurring extract from bacteria. The treatment options will be provided at no cost to the homeowners. Both options will help to eradicate European grapevine moth and greatly reduce the risk of spread to commercial vineyards, according to the press release.Â
To date, the moths has been detected in 10 California counties: Fresno, Merced, Monterey, Napa, San Joaquin, Santa Clara, Santa Cruz, Sonoma, Solano and Mendocino. The pest is known to occur in southern Asia, Japan, Europe, and North and South America. It primarily damages grapes, but is also known to feed on other crops and plants.
Earlier this month, three additional European grapevine moths were trapped within the quarantined area.
