According to University of Illinois research, the initial SDS infections that occur on the roots and crowns of young soybean plants occur as early as the seedling stage. Roots have a blue coloration when infected and subsequent Root rot affects seedling health.
Sudden Death Syndrome (SDS) is one of the top yield-robbing pests in soybeans. Over the last five years, average annual damage caused by SDS cost soybean growers more than 44 million bushels in lost yield, and the spread of the disease continues to climb. SDS has been documented in almost every state where soybeans are grown. And while reported losses often represent 20-30 percent of a crop, yields can be cut by more than 70 percent.
- SDS strips soybeans of production potential. But proper early-season preparations can help alleviate possible late-season losses.
- SDS is caused by the fungus Fusarium virguliforme, which spreads through soil movement from field to field. The fungus can survive and overwinter in crop residue.
Melissa Chu, ILeVO® product manager, urges growers to pay attention to the possibility of SDS in their field. Once SDS is in a field, it stays there, and it’s a disease growers have been fighting for decades. Studies at Southern Illinois University Carbondale confirmed greater soil compaction leads to higher levels of SDS.
- Often SDS develops in cool, wet weather and in compacted soil.
- More moisture for longer periods of time in the soil enables the SDS pathogen to penetrate the soybean plant via the root system and put stress on the plant.
At flowering, the SDS fungus produces toxins that cause foliar destruction, including leaf drop and aborted pods. Plants may pull easily from the soil. Soybean stem tissue turns white, while areas between leaf veins turn bright yellow and then brown. The brown tissue may fall out and leave large holes in the leaves. Toxin production and symptom severity will vary by climatic conditions and the level of SDS resistance in the varieties grown.