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United States Department of Agriculture

Agricultural Research Service

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Location: Horticultural Crops Research

2011 Annual Report

1a. Objectives (from AD-416)
1. Optimize spray timing for eriophyid pest mite populations. 2. Determine impact of low-impact fungicide spray regimes on pest and predatory mite populations. 3. Determine impact of often used fungicides on predatory mite population density, mortality (juvenile and adult), fecundity, oviposition rate and longevity.

1b. Approach (from AD-416)
Efficacy spray trials will be conducted in vineyards with known eriophyid pest mite infestations to determine the optimal timing for control of rust and bud mite pest populations in vineyards and minimize damage during early season. Field trials will be conducted to examine the effects of reduced fungicide use on the development of mite populations and powdery mildew disease development. Field trials will be conducted with two goals in mind. Optimize (1) conventional and (2) organic seasonal fungicide spray regimes in order to mitigate mite pest populations and allow survival of beneficial arthropods such as T. pyri. Bioassays will be conducted to verify field trials using a Precision Potter Spray Tower to test the toxicity of multiple fungicides, including several often used formulations of sulfur, stylet oil, several classes of synthetic fungicides and whey powder, an alternative ‘soft’ fungicide, on T. pyri under laboratory conditions. Documents Grant with Oregon State University

3. Progress Report
Vineyards throughout Oregon have recently developed Short Shoot Syndrome, which is correlated to the pest mite, Calepitrimerus vitis. This vineyard specific pest feeds on developing buds resulting in stunted shoots and crop (cluster) loss. Typhlodromus pyri is the dominant predatory mite in western Oregon vineyards and is believed to play an integral role in managing C. vitis populations. Intense fungicide programs are maintained in vineyards throughout the growing season and are believed to be detrimental to predatory mite populations causing increased pest mite outbreaks. Predatory mite preservation and enhancement are integral to successful biological control programs in western vineyards. In field trials, the use of synthetic fungicides interspersed with sulfur resulted in adequate pest mite control without negatively affecting T. pyri populations. Sulfur-only applications sometimes resulted in pest mite outbreaks. Synthetic fungicide-only applications resulted in higher pest and predator mite numbers. Our laboratory trials confirm trends observed in the field. Sulfur applications negatively affected juvenile T. pyri longevity and reproduction but not adults. Stylet oil had a negative impact on beneficial mite populations. Laboratory trials on pest mites showed that a sticker/spreader such as oil plays an important role to control pest mite populations. The project was monitored by meetings, e-mail, and phone calls.

4. Accomplishments

Last Modified: 08/17/2017
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