Presenters: Drs. Walt Mahaffee and Jay Pscheidt
In 2015, we received a number of reports of powdery mildew not responding to FRAC 11 fungicide applications (Abound, Flint, Sovran). Samples from these vineyards had E. necator isolated that were resistance to both FRAC 11 and FRAC 3 fungicides (Tebucon, Procure, Rally, Vintage, Inspire Super). Further surveys of the Willamette Valley, Southern Oregon, and Hood River, indicated that greater than 80% of vineyards had E. necator populations with both FRAC 3 and FRAC 11 resistance population. In 2016, there were several control failures in vineyards that were again shown to be associated with E. necator populations resistant to both FRAC 3 and FRAC 11 fungicides. These data indicate these fungicide groups may not be managing grape powdery mildew as well as expected.
A recent OWB research bulletin alerted growers about this potential problem and many have expressed concern and the need for more information and recommendations. In order to provide these, OWRI is presenting an information and Q&A webinar with Dr. Walt Mahaffee, research plant pathologist at the USDA Agriculture Research Service horticulture unit in Corvallis; and Dr. Jay Pscheidt, OSU extension plant pathology specialist. Together they will provide research background on powdery mildew resistance, and recommendations, and answer questions from webinar participants.
The webinar will be recorded and made available on the OWRI website in its webinar archive. Please address questions to Denise Dewey at 541.737.3620 or denise.dewey@oregonstate.edu.
United States