Sudden Death Syndrome, or SDS as it is commonly called, is rearing its ugly head this year. SDS is caused by Fusarium Solani, a fungus found in the soil. Normally it tends to be seen in the more southern areas of our sales region but this year it is pushing its way up into Minnesota, Wisconsin, and Michigan.
Identifying: The tell tale sign of infection is seen in the leaf with tissue dying between the leaf veins (Figure 1). Other diseases and chemical damage can show the same type of leaf damage so it is important to split open the stem and roots and examine the tissue there. SDS infected roots have light brown streaks in the tissue between the center (pith) and the outside layer of the stem (Figure 2).
This is different from Brown Stem Rot. In Brown Stem Rot infected plants, the pith is brown while the rest of the stem is a normal white.
Environment: Normally SDS is usually seen in saturated and compacted soils. This year’s heavy spring and early summer rains brought these conditions to the forefront and made an ideal environment for SDS. In our own show plot on our farm we have seen SDS for the first time. The interesting thing is that with the exception of one variety, the only places SDS developed were the two compacted strips caused by tire tracks that run perpendicular through the plot.
Control: Not many options exist to control SDS. There is no true genetic resistance, although past SDS outbreaks have caused highly susceptible varieties to be removed from the breeding pool. Still any variety can get SDS. Like White Mold tolerance, certain genetics do better than others and we do rate our products for SDS tolerance.
Tillage to break up the compaction and increase water flow in spots prone to SDS may be beneficial. Rotation has proven ineffective as the fungus is found commonly in the soil. Foliar spraying has not shown a lot of promise as the infection occurs in the root structure and foliar sprays typically do not penetrate to that part of the plant.
Later planting will help reduce the chance of SDS, but remember this is a two edged sword. Later planting also has a tendency to reduce yields.
One product out there that may be of interest for those with chronic SDS hotspots is a seed applied treatment from Bayer called ILevo. This treatment has shown strong control of the Fusarium that causes SDS. A grower must weigh the chance of infection versus the added seed cost to see if it makes sense.
For most people SDS is a once every-few-years event. I would not change my practices or variety selection unless the event is chronic. At that point some deep tillage to break up saturation and compaction would be in order. In addition, using a highly rated SDS tolerant variety with ILevo seed treatment would help in those fields with chronic SDS conditions.
BY ALEX RENK