Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2005
Publication Date: 8/1/2005
Citation: Grove, G.G., Falacy, J., Galloway, H., Mahaffee, W.F., Turechek, W., Peetz, A.B. 2005. Detection of erysiphe necator in the air of grape vineyards in eastern washington. Phytopathology. 95:S36.
Technical Abstract: Current grapevine powdery mildew risk assessment models use vine phenology and prevailing weather to assess disease pressure and adjust spray intervals. This study endeavored to devise a reliable, inexpensive, and rapid means of detecting Erysiphe necator(En)in the vineyard air prior to disease onset. We have developed primers that when used in PCR reactions can differentiate En from 46 other powdery mildews common in California, Oregon, and Washington. Vineyard air was sampled using Rotorod samplers with glass rods coated in silicon grease. PCR reactions indicated that air samples were devoid of En prior to bud burst. The initial detections occurred after budburst during theoretical ascospore release events resulting from a 3.5 mm precipitation event and a second 5.8 mm event that occurred one week later. Both early positives occurred during periods of ascospore release as confirmed by the presence of ascospores on impaction tapes from a Burkard volumetric spore trap. Subsequent negative sampling results intimated that the vineyard was devoid of En propagules during incubation and latent periods. Detection resumed several days prior to the visual appearance of powdery mildew signs and continued during subsequent disease development. Our results may represent the first step towards the inclusion of an “inoculum availability component” in powdery mildew risk assessment models.