Research aims to control vegetable disease

By Jonathan Veit

Growers of pickling cucumbers and other crops susceptible to infection by downy mildew may someday benefit from higher yields and lower production costs thanks to collaborative research by Clemson and North Carolina State University.  

“If we can understand the weather factors that lead to a high risk of downy mildew infection, then we can reduce the need for fungicides, reduce the cost of cucurbit crop production and increase yield,” said Anthony Keinath, plant pathologist at Clemson’s Coastal Research and Education Center in Charleston.  

Keinath recently was awarded a USDA grant to develop a model for predicting downy mildew infection risk to cucurbits, a family of plants that includes various squashes, melons and gourds. His research is part of a wider study being conducted by N.C. State for USDA.  

Downy mildew also contributes to a decrease in production of pickling cucumbers in South Carolina. Keinath’s research has shown a 68 to 90 percent loss of yield due to infection, which would mean $900,000 in potential losses to South Carolina pickle growers. A 2004 epidemic of downy mildew infection cost U.S. growers an estimated $20 million in lost yield.  

Keinath and his collaborators hope to quantify the effects of weather variables such as temperature, humidity, rainfall, dew point and cloud cover on the risk of infection.  

They also hope to validate the current cucurbit downy mildew forecasting system that is composed of 25 collaborating institutions in the eastern United States, California and Ontario, Canada, that report weather and other factors to a central online database.  

Currently, growers of cucurbit crops, such as pickling cucumbers and cantaloupes, must spray costly fungicides to protect their crops from infection. In Michigan, the largest U.S. producer of pickling cucumbers, fungicide sprays cost farmers $6 million annually.