|Mahaffee, Walter - Walt|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/29/2005
Publication Date: 10/5/2005
Citation: Grove, G.G., Galloway, H., Lunden, J., Spotts, R.A., Mahaffee, W.F. 2005. Detection of podosphaera clandestine in the air of cherry orchards using pcr and species-specific primers. Phytopathology.
Technical Abstract: Development of a sensitive, rapid, and accurate means to detect Podosphaera clandestine(Pc) in orchards could prove useful in disease management. The purpose of this study was to develop an inexpensive and sensitive means for the early detection of Pc in orchard air. A PCR assay was developed to differentiate Pc from other powdery mildews common in the northwest United States. DNA was extracted from mycelia, conidia, and/or cleistothecia collected from cherry leaves using a Burkard cyclonic surface sampler. Primer pairs were developed to select unique regions of the internal transcribed spacer (ITS) region of Pc ribosomal DNA. The primers generated an amplicon from Pc, but did not generate amplicons from erysiphaceous species collected from 46 disparate hosts from 26 vascular plant families. The assay facilitated the detection of low levels Pc inoculum in air samples within hours of collection during field studies prior to disease onset. A method utilizing a Rotorod air sampler proved to be the most consistent for detection. It detected propagules of Pc during two early season ascospore releases that were induced by rain. Furthermore, propagules were detected, after a latent period, before symptoms were observed. This approach may prove useful to signal the commencement of the fungicide control program.