18 SUDDEN DEATH SYNDROME (SDS) is set to follow the progress of Soybean Cyst Nematode (SCN), becoming a severe and consistent problem for Ontario soybean farmers in the coming decade. Researchers at the University of Guelph and the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) are trying to get ahead of the problem by adding more SDS-resistant genes to the province’s pool of soybean germplasm. GENETIC RESISTANCE LACKING SDS is considered the second most devastating soybean pathogen in southwestern Ontario. The yield-robbing disease also continues to spread across the province, with the most effective means of control coming from SDS-resistant cultivars. Selection for varieties with SDS resistance is the best strategy to minimize field infection and yield losses. Variety selection can be enhanced with the use of seed treatments currently available to reduce early season infection and boost plant health. As happened with SCN, however, the few genes responsible for resistance can lose effectiveness over time. This puts breeders, seed companies, and farmers in a precarious position. “We now realize SDS is what soybean cyst nematode was 10 years ago. It will be a problem in new zones,” says Dr. Milad Eskandari, an associate professor and plant breeder with the university. To date, Eskandari says breeding programs for food grade soybeans have not focused on SDS resistance, largely because it was not considered a looming problem. Now, he Sudden Death Syndrome EXPANDING VARIETY OPTIONS Matt McIntosh SUDDEN DEATH SYNDROME (SDS) IN SOYBEANS. PHOTO COURTESY OF ALBERT TENUTA. and fellow plant agriculture professor Dr. Istvan Rajcan are working with OMAFRA and AAFC colleagues to find other resistance genes within varieties suited for Ontario. Those genes will subsequently be introducing into the province’s germplasm bank and existing SCN-resistant varieties. SDS SYMPTOMS AND IDENTIFICATION As described in a Field Crop News article by Albert Tenuta, OMAFRA field crops plant pathologist, SDS is a root rot disease caused by an aggressive strain of the common soil-borne fungal pathogen Fusarium solani. Infection frequently occurs during the first six weeks after emergence, with symptoms generally developing at the mid-pod reproductive stage. The presence of soybean cyst nematode can make SDS worse, since the Research
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