Sudden Death Syndrome (SDS) is a disease in soybeans that has been prominent in the US Mid-West for many years, but is now becoming more prevalent in Ontario.
SDS symptoms will start to show up in a soybean from bloom to pod fill, but is most commonly seen between R3 to R6. The symptoms to identify SDS are light green spots on the leaf surface between the leaf vein and will generally show up partway up the canopy of the plant.
These spots will then turn yellow and then brown as the leaf tissue dies. The areas of the field that will generally show these symptoms first are the wet, or poorly drained areas. They can show up on a single plant or in oval areas in the field. SDS is caused by Fusarium Solani which is found in most soils and will affect the plant's lateral roots.
What causes the disease to infect the plant could be many things from Cyst, to other root diseases, and weather events. Fusarium Solaniwill infect the plant early in the season but symptoms can't be seen until later as stated above (commonly R3 to R6). When the plant shows symptoms it will eventually lose all the leaves, but the leaf petioles stay on the plant. These infected plants will not have any soybeans on it at harvest.
So what is the best way to prevent/avoid getting SDS in your soybeans?
The Best Management Practices are:
- Improved Drainage- keeping the roots healthy
- Rotating Crops- help to manage SCN in the field
- Tillage- crop residue carries more disease
- Variety Selection- Choosing SCN resistant varieties as well as reviewing for SDS ratings.
Also when evaluating for SDS in a soybean field, Brown Stem Rot (BSR) looks very similar, so here are the differences to help.
- BSR causes browning of the pith (inside of the stem), SDS doesn't
- BSR does not cause root decay (root dead and rotting), SDS does
- BSR shows up even later in the season than SDS (R5-R6).