College of Agricultural, Food, and Environmental Sciences
Wine and Viticulture
BS in Wine and Viticulture
In this study, we hoped to record Pacific spider mite (Tetranychus pacificus) and Willamette spider mite (Eotetranychus willamettei) survival, development, reproduction, and longevity in the presence of various fungicides and on water stressed Chardonnay (Vitis vinifera) cuttings. It has been observed in the San Joaquin Valley that Pacific mite populations drastically increase under warm dry conditions (Hanna et al., 1997a), although it has never been explained exactly why. Water stressed grapevines may elicit responses in the plant that effect mite reproduction or longevity, or there may be a physiological or behavioral response from the spider mites under these conditions. While these same population responses to drought have not been observed in Willamette mite, collecting information on these types of conditions may unveil interesting results. There has also been evidence that shows broad spectrum pesticide applications may be responsible for temporary reduction in Pacific spider mite populations, but due to the loss of natural enemies may allow a more severe population explosion to occur later (Prischmann et al., 2005). Sulfur has shown effects on Pacific mite populations (Costello, 2007) and other fungicides may also have interactions we are still yet to discover. More investigation into these interactions could possibly allow us to better manage spider mites in California vineyards.