Late blight symptoms include the appearance of dark lesions on leaf tips and plant stems. In humid conditions, white mold appears under the leaves. Infected potatoes show gray or dark patches outside; inside, such potatoes show reddish brown lesions. A threat to home gardeners and commercial farmers, the disease can wipe out tomato and potato fields within a week.

The disease is caused by Phytophthora infestans, the most significant pathogen of potato, and a noteworthy tomato pest. Spores of the pathogen primarily travel in air, eventually landing on plants where the spores colonize leaves and cause them to die. Spores also can enter the soil, reach potato tubers, and destroy them. Available fungicides tend to be expensive and have potentially adverse environmental effects. Moreover, some strains of the pathogen are resistant to some fungicides.

“This grant to Dr. Judelson builds on historic UC Riverside strengths in research on this pathogen and is one more acknowledgement that UC Riverside is a leader in agricultural research,” said Donald Cooksey, divisional dean for agriculture and natural resources in UCR’s College of Natural and Agricultural Sciences. “By leading research on managing late blight, we will help protect the productivity of tomato and potato farmers worldwide.”

The research project will emphasize providing growers with better tools for managing the disease. These include better systems for making disease management decisions, plant varieties that are more resistant, tools for rapid identification of the pathogen, and tools for characterizing pathogen strains. The researchers also will test and expand the use of social media and smartphone technology to communicate with growers.

In the United States, late blight is seen predominantly on potato in eastern states like Maine, New York and Pennsylvania, and outbreaks also occur in the Midwest and West. Tomato production from Florida up the East Coast is also vulnerable to the disease. In California, late blight is mostly seen in the central valley in the early season, when conditions are moist and cool.

“For many years, UCR has been on the cutting edge of research to eradicate agricultural pests,” said Rep. Ken Calvert, R-Calif. “This grant acknowledges the valuable work that UCR does and with the grant they will be able to help farmers around the world deal with late blight. I commend Professor Judelson for his work in plant pathology and the entire staff of the UCR College of Natural and Agricultural Sciences for the contributions they will be making to combat the devastating impacts of late blight.”

Judelson will be joined at UCR by Thomas Girke, an associate professor of bioinformatics, who will help sequence strains of Phytophthora infestans, and scientists at Cornell University, N.Y.; USDA-Agricultural Research Service, Corvallis, Ore.; the University of Idaho; the Scottish Crop Research Institute; North Carolina State University; the University of Florida; the University of Kentucky; La Universidad Autónoma Chapingo, Mexico; Boyce Thompson Institute, N.Y.; the University of Maine; Oregon State University; Pennsylvania State University; the University of Wisconsin; the University of Maryland; the University of South Carolina; and Purdue University, Ind.

The grant, which became effective March 1, 2011, has a strong undergraduate research component. Of the $9 million total award, $4.3 million is budgeted to UCR for research and education activities; the rest will be shared by the other 16 institutions.