Plant pathologists with The American Phytopathological Society (APS) are reporting a significant increase in the occurrence of Phytophthora blight of vine crops, including cucumbers, pumpkins, and squash, in many vegetable-growing regions of the United States. This devastating disease, caused by a soilborne pathogen called Phytophthora capsici, often results in nearly total yield loss.

According to Mohammad Babadoost, a plant pathology professor at the University of Illinois, Phytophthora blight has become one of the most serious threats to production of vine crops, or cucurbits, both in the United States and worldwide. "Recent outbreaks of Phytophthora blight have threatened pumpkin and other cucurbit industries in Illinois, where approximately 90 percent of processing pumpkins produced in the U.S. are grown," said Babadoost. "Because of heavy crop losses, growers often have to abandon their own farms and move into different areas, sometimes traveling more than 50 miles, to find fields not infested with Phytophthora capsici," said Babadoost.

Phytophthora blight can strike cucurbit plants at any stage of growth. The infection usually appears first in low areas of the fields where the soil remains wet for longer periods of time. The pathogen infects seedlings, vines, leaves, and fruit. The disease is usually associated with heavy rainfall, excessive-irrigation, or poorly drained soil. Frequent irrigation increases the incidence of the disease.

Currently, there are no cucurbit cultivars with measurable resistance to Phytophthora blight. Plant pathologists are working to find new methods of controlling this disease. "In addition to exploring cultural management strategies, plant pathologists are assessing the possibilities of using induced resistance in plants, biocontrol agents, and fungicides for control of this disease in cucurbits and other crops," said Babadoost.

More on this subject including details on the disease, the pathogen that causes it, and current control methods can be found in this month’s APS feature article at http://www.apsnet.org/online/feature/cucurbit/. The American Phytopathological Society (APS) is a non-profit, professional scientific organization dedicated to the study and management of plant disease with 5,000 members worldwide.xx