News : Tillage not a long-term solution for soybean SDS, say experts

If you were one of the many Iowa farmers to be hit with Soybean Sudden Death Syndrome (SDS) this year, tilling up the soil and remaining crop residue is not a good long-term solution. In fact, tillage can actually lead to poor soil drainage and compaction which are two conditions that promote SDS.

SDS is caused by a fungus present in many Iowa soils that infects soybean roots and produces a toxin that moves up the plant and kills the leaves. The weather in 2010 was ideal for the development of the SDS disease – temperatures below 60˚F at planting, moderate temperatures during the growing season, and constant wet conditions.

According to Iowa State University plant pathologists, there are a number of things farmers can do to prevent SDS from happening.

· Use resistant soybean varieties. Consult with seed companies and agronomists for information about varieties resistant to SDS.

· Grow SDS resistant soybeans in fields with the greatest history of SDS problems.

· Take measures to avoid or reduce soil compaction.

· Plant later in the spring in fields with a history of SDS.

· Consider improving soil drainage, if possible, in fields with recurring SDS problems.

USDA-Natural Resources Conservation Service (NRCS) State Agronomist Barb Stewart says conventional tillage will make drainage and soil compaction problems worse over time. In fact, Stewart says tillage reduces soil quality. “Tillage damages soil structure, reduces organic matter in the soil, and increases the risk of erosion,” she says.

Stewart says soil quality is directly related to soil performance. “Healthy, quality soil will do a better job of resisting erosion, cycling crop nutrients, supporting root growth, infiltrating water, and sequestering carbon,” she says.

Reducing tillage also means saving money. “It means fewer trips across the field and less wear and tear on equipment,” says Stewart. “Unless you just like wasting fuel, I ask that you do something else this fall and leave that residue alone which will protect the soil quality characteristics you’ve built over the last year.”

For more information about Soybean SDS, contact the Iowa State University Department of Plant Pathology at 515-294-1741. NRCS agronomic information is available at www.ia.nrcs.usda.gov/technical/.