Sudden Death Syndrome Upon Us

August 6, 1999
Reports of sudden death syndrome (SDS) are beginning to come in; symptomatic patches in fields are obvious in many fields even from the road. Matt Montgomery of the Sangamon/Menard Extension Unit reports scattered SDS in several fields. I also had the opportunity to split open my first SDS stems of the season at a field diagnostic clinic hosted by Georgia Steffen of GMS labs in Cropsey, Illinois, earlier this week. So the SDS situation is beginning to heat up; keep an eye out for further development.

Weather conditions were favorable for SDS infection this spring. Infection by the Fusarium fungus that causes this disease occurs about 30 days after planting. Fields were still pretty wet at that time, which is conducive to SDS infection. We had record levels of SDS in Illinois last year, and this year's weather conditions are very similar to last year's, so keep a close eye out for this disease in the next several weeks. The later in the season the aboveground symptoms appear, the less yield loss you can expect. When aboveground symptoms are evident, the seed will not mature any further.

Expect SDS to show up first in low spots where other root rots may have been a problem earlier in the season or in areas of the field where soybean cyst nematode (SCN) has been a problem. Although neither SCN nor other root infections are necessary for SDS infection, they all share similar environmental factors for disease development, so you will most likely find them in similar locations. Also keep in mind that aboveground symptoms of SDS are nearly identical to another root disease, brown stem rot. You must split open the stem to get a definitive diagnosis. This is important for variety selection to manage brown stem rot in coming seasons. For further discussion of SDS symptomatology and management, see issue no. 19 (July 30, 1999) of the Bulletin.--Suzanne Bissonnette

Author: Suzanne Bissonnette