Published on Tuesday, January 15, 2019
Sudden death syndrome (SDS) was first documented in the United States in Arkansas in 1971, and has continued to spread. In the last 20 years, the disease has become increasingly prevalent in the northern soybean growing regions. Twenty years ago, many northern soybean growing states had no documented cases of SDS, or at least, it was not considered a big threat. Now, according to data, (Allen et al. 2017) between 2010 and 2014, SDS ranked third in causes of yield loss in the northern soybean growing states, only behind soybean cyst nematode (SCN) and seedling diseases.
Why has SDS become more important in the northern U.S. growing area?
Firstly, SDS favors cool, wet conditions, which are often common in the northern U.S. Secondly, the trend of planting both corn and soybeans early to maximize yield also increases the chances of encountering prolonged cool, wet conditions after planting. Compaction also plays a role in occurrence of SDS, and poorly drained soils and large equipment can increase the risk of compaction during field operations. In addition to weather, being a relatively new disease in northern areas and the corresponding soybean maturities means there has been less selection for genetic resistance to SDS in germplasm than in later maturities.
There is not a perfect answer for combating this disease, but there are some things that can help reduce the risk. When products that have high resistance scores to SDS, maintain adequate protection from other agronomic concerns relative to the area, and contain the desired herbicide traits. If possible, plant fields with the most severe history of SDS last in order to reduce the chance of encountering cool, wet soil conditions. With other diseases, crop rotation can decrease risk but unfortunately, the most common crop used in rotation with soybeans, corn, does not reduce SDS incidence.
In addition, there has been debate about the role that SCN plays in SDS infection and severity. Regardless, SCN is the single most damaging pest in soybeans, so control is a very important consideration. SCN continues to evolve. In some areas it is overcoming PI88788, the primary source of genetic resistance. Utilizing Peking genetic sources in addition to new seed treatments are important tools to help manage SCN resistance issues.
Recent developments in seed treatment technology provide some level of protection against both SCN and SDS. The seed treatment product ILeVO® can decrease the severity of SDS and also has activity on SCN in the root zone. Biological products like Nemasect™ have the ability to reduce SCN infection. ILeVO is available as an upgrade in Beck's Escalate SDS, and Nemasect now comes standard in our Escalate® yield enhancement system.
SDS will continue to be a concern in much of the soybean growing area of the United States, but with continued improvements in genetic resistance and seed treatments that impact both SDS and SCN, it is a disease that can be managed successfully with limited impact on soybean yields in most fields.
Author: Pat Holloway
Categories: CropTalk, 2019