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Sudden Death Syndrome always a concern in soybeansPosted Monday, January 17, 2011, at 3:08 PM
Sudden Death Syndrome (SDS) is a disease that often strikes portions of fields with the highest yield potential. SDS was first observed in Arkansas in 1971 and now is found in most major soybean producing areas. The impact of SDS on soybean yield can be devastating. Losses from whole individual fields have been reported as high as 40%, while affected areas were reported to have yield losses of up to 80%.
SDS management options include avoiding or reducing soil compaction, improving soil drainage in fields where SDS problems occur, planting fields with a history of SDS later in the spring, planting cyst nematode resistant varieties, and planting SDS resistant varieties.
SDS resistant varieties are very important to a SDS management program. Keep in mind that no variety is completely resistant to SDS. However, there are varieties that perform very well in severe SDS environments and this is expressed as less foliar symptoms than fully susceptible varieties. The severity of the disease on resistant varieties greatly depends on the weather and the specific conditions of each field.
Iowa State University has released a new publication titled Sudden Death Syndrome-Resistant Soybean Varieties for Iowa - PM 3009. This publication is available as a free download at http://www.extension.iastate.edu/CropNew.... This publication lists over 300 soybean varieties resistant to SDS in maturity groups I, II, and III. The varieties in he publication were submitted by seed companies and are marketed as SDS resistant by the companies. Different seed companies evaluate their varieties under different conditions and locations and may use slightly different criteria. This could result in ratings that may or may not be comparable to ratings of other varieties from other companies.
Another good source for information on SDS resistant soybean varieties is the Soybean Sudden Death Syndrome Research project at Southern Illinois University (SIU). Their website reports the results of SDS screening for 800 varieties in 2010 at SIU at Carbondale for maturity groups I thru maturity group V. The results of this were produced at SIU and provides variety to variety comparisons at the same location using the same criteria. The 2010 results as well as results from 1999 thru 2009 are available at this site http://soybean.sius.edu/ .
SIU calculates a disease index for each variety evaluated. The SDS disease index is calculated as a product of disease incidence and disease severity. It reports the foliar disease index and the relative disease index. The relative disease index compares each entry to a susceptible check appropriate for each maturity group.
Remember, there are no varieties completely resistant to SDS. SDS resistance does not ensure 100 percent control of the disease but often results only in less foliar symptoms than fully susceptible varieties. The severity of the disease on resistant varieties depends greatly on the weather and specific conditions of the field.
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As our local University of Missouri Agronomy Extension Specialist, Crook has been writing a column for the print edition Agriculture page for the past three years and we will now be sharing it on our web version. Crook has a bachelor and masters degree in agronomy from University of Missouri and received his doctorate in Agronomy from Kansas State University. He was in soybean variety development research for 22 years for various seed companies and has been Saline County's agronomy specialist for 10 years.