In a recent study, 45 species of crop and weed plants were screened for their susceptibility to P. capsici. Although 22 crop species succumbed to the disease, 14 did not.
Mohammad Babadoost, a plant pathologist in the College of Agricultural, Consumer and Environmental Sciences, believes that rotating the 14 resistant vegetable varieties may serve to wait out the pathogen until it is safe to once again plant pumpkins or other crops susceptible to P. capsici.
"Crop rotation is already being used by pumpkin growers as an important component of disease management," Babadoost said. "Most pumpkin growers in Illinois follow at least a short-term crop rotation. However, most growers have experienced heavy losses when carrot, lima beans, pea, pepper, snap bean, and tomato were grown prior to pumpkin."
In order to make crop rotation a successful solution to waiting out the pathogen, a critical question remains to be answered: How long does the pathogen stay alive in the soil?
"Unfortunately, we don't know how long," Babadoost said. "Currently, I have a graduate student investigating that. We are trying to work out the problem piece by piece, then develop effective strategies to manage this disease. Definitely, the study that [Donglan] Tian completed provided us with very valuable information in dealing with this destructive pathogen."
Soybean, corn, and wheat, the major crops grown in Illinois, did not become infected, and there is no report indicating that these crops are hosts of P. capsici. The other 11 vegetable crops that, when inoculated with P. capsici, did not develop symptoms of the disease are basil, broccoli, cabbage, cauliflower, celery, chive, dill, kale, kohlrabi, mustard and parsley.
The 22 vegetable crop seedlings that became infected and developed symptoms of the disease in the study are: beet, carrot, eggplant, green bean, lima bean, radish, snow pea, spinach, Swiss-chard, tomato, turnip, onion, pepper and a long list of vine vegetables including pumpkin, cantaloupe, cucumber, gourd, honeydew melon, muskmelon, squash, watermelon and zucchini.
The incidence of fruit rot on pumpkins caused by P.capsici has dramatically increased in Illinois, causing yield losses of up to 100 percent. "Jack-o-lantern pumpkin is an important crop in Illinois, and approximately 90 percent of the commercial processing pumpkin produced in the United States are grown in Illinois," Babadoost said. "So this is an economic problem for the state."
Babadoost and Donglan Tian, a graduate student in crop sciences, completed the study, which appears in the May issue of Plant Disease, a journal of the American Phytopathological Society. The research was supported in part by funds from North Central Region Sustainable Agriculture, Research and Education, the Illinois Department of Agriculture and Nestle Food Inc.