Luca Brillante*, Guadalupe Partida, Khushwinder Singh, Kaylah Vasquez, Nathan Mercer, Kent Daane
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Vineyard mealybugs (Hemiptera:Pseudococcidae) are a matter of increasing concern for grapegrowers, as economic losses resulting from infestations continue to increase. Several species of mealybugs are present in California, but the vine mealybug (Plano­coccus ficus Signoret) is most problematic. It is an invasive species, introduced ~20 years ago and not yet under control. In a large vineyard trial, this project compared the efficacy against mealybugs of several products commercially available in organic production: pyrethrins, neem oil, diatomaceous earth, Chromobacterium subtsu­gae, stylet oil, and potassium salts of naturally derived fatty acids. The project also controlled for side effects on grapevine physiology and grape composition related to spraying dusts and oils on leaf and berry surfaces. The experiment was set up as a randomized complete block design with four treatments plus control and four repli­cates. Each replicate was one acre, for a total of 20 acres, and repeated in two years with different products. The vineyard was planted with Pinot noir and moderately infested with mealybugs. None of the products significantly reduced the number of mealybugs on the trunk or leaves, and none had negative or positive effects on plant physiology or grape composition. This project provides new and unbiased informa­tion that will help organic growers make informed decisions on what products to apply for controlling mealybugs in organic vineyards.

Funding Support: American Vineyard Foundation