The overwhelming majority (75 percent) of grape growers and pest control advisers (PCAs) surveyed by the University of California use the Gubler-Thomas Powdery Mildew Index (PMI) for making decisions about powdery mildew management.

This UC survey was conducted in collaboration with Western Farm Press and its online continuing education (CE) program. The survey specifically targeted those who had completed the CE course, “Grape Powdery Mildew Control in California Vineyards” on the Farm Press CEU portal.

UC Davis plant pathologist Doug Gubler and Travis Lybbert, associate professor, agricultural and resource economics, approached Farm Press to source the Penton Ag CEU database for the extensive survey.

Gubler was the major contributor in the development of the Farm Press powdery mildew management course several years ago and has contributed to updating a couple of times from his extensive, ongoing research efforts.

Gubler said the data gathered through the Farm Press survey was “invaluable and instrumental in allowing us to gain insight into powdery mildew control programs and reasons for use of products and use or nonuse of the Gubler-Thomas Powdery Mildew Model.” Gubler has invested three decades of research into managing powdery mildew.

This disease prediction model is not only widely used in California, but is recognized worldwide for its predictability accuracy in assessing environmental conditions conducive to powdery mildew development and when to treat for it.

“The survey that we were able to conduct in collaboration with Western Farm Press will contribute to an ongoing effort to understand how growers modify their disease management strategies based on disease forecasting models such as the powdery mildew model,” said Lybbert. “By quantifying the environmental benefits associated with these adjustments and identifying constraints on the use of disease forecasts, we also hope to improve the design, dissemination and use of these models.”


Want access to the very latest in agriculture news each day? Sign up for the Western Farm Press Daily e-mail newsletter.


“The Western Farm Press staff and Penton Media Agriculture Group Digital Sales/Marketing team were thrilled to work with Dr. Gubler and Dr. Lybbert in conducting this electronic survey,” said Harry Cline, Farm Press. “We consider this collaborative effort with UC Davis a validation of the quality of the online Farm Press CE program initiated nine years ago with the first course.”

There are currently more than 10,000 registrants on the CEU portal from every state and more than 60 countries. Almost 70,000 courses have been completed since the CE program began. Twenty courses are not available on the CE portal. More than 20 states have accredited Farm Press courses. All courses are accredited for Certified Crop Adviser credit.