- Summer 1999 "Update" Newsletter Article -
Mite study results lead scientists to next questions
Copyright © 1999. All rights reserved.
Spider mites have long been known to be an important pest to grape vineyards in California. Their sucking of juices weakens the plant and can cause delayed fruit maturity, lowered sugar levels and reduced yields.But is it really the mites that are causing all those problems for a normally healthy vine, or is it perhaps a "sick" or ailing vine that draws the mites to it? That is the question Fresno State researcher Mark Mayse hopes to eventually answer through research studies supported by the university’s integrated pest management (IPM) program.
In a new research report published by the California Agricultural Technology Institute (CATI), Mayse details a study of mite populations in a Chardonnay vineyard in Mendocino County of northern California. The study tracked aspects of vine growth and production under known mite infestations. Results showed several clear correlations – among them that when mite levels were higher, grape sugar content and overall yields were lower.
The consistency of the correlations with the results of some prior studies should lead researchers into the next realm of questioning – whether mites attack healthy vines and cause the production problems, or whether they are drawn to unhealthy vines and exacerbate existing conditions.
"Further studies will be needed to determine how these two relationships typically impact vineyard production systems," Mayse said.
The new publication is titled "Relationships Between Mite Density and Grape Production" and can be ordered using the publications order form on Page 7. It also may be viewed on the VERC web site.
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