Purdue News
Purdue News
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April 13, 2001 Early soybean planting means risk, not better yieldsWEST LAFAYETTE, Ind. – Planting soybeans early this spring will not produce better yields and could cause disease problems later this summer, says a Purdue University expert. "Soybeans planted early are at greater risk of sudden death syndrome than soybeans planted later," says Greg Shaner, Purdue professor of botany and plant pathology. "The majority of severe sudden death syndrome samples submitted to Purdue by soybean growers have come from early-planted fields." He says other factors for the disease are susceptibility of the soybean variety, weather and how often soybeans are grown in the field. As soon as the weather warms, some producers are anxious to get into the fields and begin planting. However, Purdue research has shown there is no yield advantage to early planting and it stresses the plants, increasing the risk for disease problems. "Producers need to keep their plants as healthy as possible," says Shaner. "Farmers get out and begin planting during 'false spring' conditions when the soil has not yet warmed up. This is a predisposing factor for SDS because normal April temperatures can return and put stress on the plant." Shaner says farmers often choose their seed based only on yield performance and give little consideration to disease resistance. "The only reason we worry about crop diseases is because they reduce yield and quality," he says. "A variety may have excellent yield potential, but if it is susceptible to a disease such as SDS, and the disease develops, the yield potential becomes meaningless." The fungus that causes SDS, Fusarium solani f. sp. glycines, resides in the soil. The disease's severity is determined by how much fungus is present, says Shaner. Therefore, last year's fields hard hit by SDS have a higher fungus population. Planting last year's soybean fields in corn won't keep farmers safe from SDS. "There is no way to avoid the threat of SDS," says Shaner. "The fungus survives in soil and can persist for several years even though soybeans are not grown. The key to reducing loss from this disease is through managing it, not avoiding it." Shaner recommends planting soybeans from May 5-20 in fields where there is a history of SDS. He also suggests planting a variety with some degree of resistance. "There are few varieties with complete resistance to SDS. However, the resistant varieties are damaged less and yield better than susceptible varieties when the disease strikes," he says. Purdue's Department of Botany and Plant Pathology and the United States Department of Agriculture's Agricultural Research Service are studying SDS resistant varieties. Shaner says research has shown the resistant varieties yield as well as susceptible varieties even without the disease. Source: Greg Shaner, (765) 494-4651, shaner@btny.purdue.edu Writer: Jennifer Doup, (765) 494-6682, jdoup@aes.purdue.edu Purdue News Service: (765) 494-2096; purduenews@purdue.edu Related Web site:
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