Cucurbit downy mildew is one of the most aggressive diseases to affect cucumbers, squash, melons, and pumpkins, however, the pathogen that causes this disease does not overwinter in the Kentucky. Each year, the pathogen is blown into the Commonwealth from areas with temperate climates where it can overwinter, including areas to the south, west, and from greenhouse producers to the north. The area the pathogen originates from has implications for which fungicides will be effective against it, as resistance has been reported from various sources. These fungicide applications average $30 - $50 per acre, per application, so a grower can go to significant expense managing this disease, and should have reasonable expectation that such expensive fungicides should be effective. After the pathogen’s arrival in KY, cucurbit crops can succumb to downy mildew in a matter of two weeks during rainy summers, often before producers have the opportunity to harvest the crop. Downy mildew is one of the most important diseases to be managed by over 2000 cucurbit producers in the Commonwealth.

Through the Specialty Crop Block Grant program administered by the Kentucky Department of Agriculture, ten sites are located throughout Kentucky to monitor for the arrival of the downy mildew pathogen. Further, extension professionals at each of these ten sites are trained in a bioassay protocol to determine whether a select number of fungicides are effective on the prevalent strains of the pathogen during the current year. The extension vegetable pathologist adapted the research protocols, coordinates the project, interprets and disseminates results, while extension agents and associates generate the research-based data for in-season guidance on cucurbit downy mildew fungicide efficacy.

Following year 1 of the program, extension agents statewide were surveyed. All responding agents (24) reported increases in their level of confidence in advising clients on cucurbit downy mildew. Agents also indicated that 26% of commercial cucurbit producers augmented their spray programs using information from the monitoring network. They reported that 22.5% of growers controlled downy mildew more effectively, and 26.4% of growers saved on production costs. Results from the monitoring network were included in Facebook posts, on the VegIPM phone-in hotline, and on the Kentucky Pest News blog. Combining these sources of information, the reach of the monitoring network was at least 5614 in 2018. Two additional years of this monitoring network will be conducted in 2019 and 2020.