New York squash sales hit $32 million in 2017, with more than 11,000 acres harvested. One of the growers’ biggest challenges in producing this delicious, healthy food? Powdery mildew. New York vegetable growers have been seeking better management solutions against this airborne pathogen for years. In 2018, two proposals were funded to tackle the problem. As is often the case with agricultural research, more work is needed.
For conventional growers, the current protocol for powdery mildew management is a weekly spray of chemical fungicides, rotating through the limited choices of fungicides not already affected by resistance to minimize its further development. There is less data to guide organic growers in choosing effective fungicides to manage powdery mildew . While disease severity varies from year-to-year, growers can count on this disease being an annual problem. Spray applications need to begin when the disease is just getting started, so frequent scouting is an important part of the management protocol.
One project, led by Amara Dunn with the Integrated Pest Management Program at Cornell examined the use of biofungicides to control powdery mildew in squash as well as white mold in snap beans.
Biofungicides are a relatively new choice on the market and have some interesting attributes. Made from microbial or botanical ingredients, they have a short pre-harvest interval and most are acceptable for organic production. Some of the products are known to reduce cucurbit powdery mildew infection, but may be less effective than conventional fungicides when used alone.
Dunn’s research sought to answer three questions:
Can we improve control by adding biofungicides to a conventional fungicide rotation?
Can we replace some conventional fungicides with biofungicides and achieve as good or better powdery mildew control?
Can we use biofungicides in an effective organic management program?
The results from the trials, conducted on Long Island and in Eastern and Western New York were mixed. None of the combinations of products tested consistently achieved any of these goals with the protocols used. While some options showed promise, overall more research is needed before any specific approach could be recommended.
In short, this project demonstrated how important research to understand efficacy of new products really is. It is critical that researchers continue to focus on understanding the benefit, if any, of these new products coming to market. Sharing the knowledge of these trials can help growers make good choices as they develop their management plans for this challenging disease.
The second project, led by Mark Rea at the Lighting Research Center at Renssalaer Polytechnic Institute was a completely different approach. It is covered here.
“It’s good to host trials and meetings because you get ideas about what to improve on your farm from a bunch of different people. I always learn a lot. The powdery mildew trial answered questions about whether the biocontrol products make sense in our rotation. For now we will stick with our conventional sprays. ”
Korona’s Korn and Produce