Issue No. 4, Article 5/April 27, 2012
Consider Risk of Sudden Death Syndrome When Planting Soybeans Early
Sudden death syndrome (SDS), caused by the fungus Fusarium virguliforme, has plagued Illinois soybean growers since the 1980s. The disease first reduced soybean yields in southern Illinois, but it has since spread across the entire state.
Although the fungus infects soybean roots very soon after planting, the typical symptoms of SDS occur on the leaves, generally when plants are flowering. These typical foliar symptoms are observed first as yellow splotches that develop into interveinal chlorosis (yellow leaf tissue between veins that remain green) and then interveinal necrosis (dead leaf tissue between veins that remain green). The foliar symptoms are caused by a toxin produced by the fungus in the roots that moves through the plant up to the leaves. In addition to the foliar symptoms associated with SDS, the fungus can cause a root rot.
A range of foliar symptoms of sudden death syndrome--from yellow splotches to interveinal necrosis.
SDS is most severe on susceptible varieties that are planted into cool soils, with planting followed by frequent rainfall. With this year's mild spring weather and early start on corn planting, much corn is in the ground, and some farmers have begun and many others soon will begin planting soybean. When planting soybeans early during a time when soil temperatures are still relatively cool, farmers should consider the risk of SDS.
In fields where SDS has been a historical problem, plant varieties with a high level of resistance to SDS. In addition, consider planting these fields last. In addition to seed company ratings for SDS resistance, information is available for some varieties that have been screened for resistance to SDS in trials conducted by the University of Illinois and Southern Illinois University (see www.vipsoybeans.org and www.scnresearch.info for university trial results).
No in-season options are available for SDS management, and currently registered fungicide seed treatments are not effective in preventing development of the disease, so it is important that the most-resistant varieties are planted in situations that favor SDS.
For more information on SDS, go to the Plant Health Initiative website (www.planthealth.info).--Carl A. Bradley
Carl A. Bradley