ARS | Publication request: Development and evaluation of detection-based air sampling programs for grapevine powdery mildew in eastern Washington

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 5, 2009
Publication Date: June 1, 2009
Citation: Costadone, L., Grove, G.G., Larsen, R.C. 2009. Development and evaluation of detection-based air sampling programs for grapevine powdery mildew in eastern Washington. Phytopathology. 99: S25.

Technical Abstract: Powdery mildew of winegrape (Vitis vinifera L.), caused by Erysiphe necator, is one of the most problematic diseases of grapevine worldwide. A real-time PCR assay using species-specific primers was developed for qualitative and quantitative detection of E necator in vineyard air samples collected by Rotorod sampling devices. Three methods (FastPrep DNA kit, UltraClean MoBio and FastPrep DNA kit for soil) were used to purify DNA of E. necator collected from air samples and evaluated with respect to conidia DNA yields. The DNA yields varied considerably with the extraction procedure used. The temporal concentration of E. necator propagules in the vineyard air was verified using a Burkard volumetric spore trap. Foliar disease incidence and severity was evaluated in leaves during both years. Regression analyses of the vineyard data revealed significant relationships between DNA signal strength and aerial spore concentrations, foliar disease incidence, and foliar disease severity during both years of the study. The findings of this study describe a rapid, reliable method to assess the presence and concentration, of E. necator propagules in the vineyard air. Further elucidation of the quantitative relationship between DNA signal strength and treatment thresholds may result in an accurate means to time initial and subsequent fungicide applications, and through the incorporation of an inoculum component make grapevine powdery mildew models more precise.