By Darren Hefty
Iowa is one of the best places in the world to farm. Some of the characteristics include: deep and fertile topsoil, plentiful moisture, and lots of sunny days. However, Iowa was one of the states hit hardest by sudden death syndrome in soybeans once again this year. There are many questions about sudden death syndrome you may have. I’ll answer some of them today and give you a take-home plan for 2015.
Here’s a quick snapshot about SDS and how you can protect your crop. SDS starts out as a fusarium infection in the roots of young soybean plants. The above ground symptoms manifest themselves in the mid to late summer and look very similar to Brown Stem Rot.
Since the problem starts very early in the season, the immediate thought is that a seed treatment solution should be possible. Up until now, we haven’t seen much help from treating the seed. One promising seed treatment is coming out this year, though – ILeVO from Bayer. Trial work done in 2014 showed less incidence of SDS and higher yields. The treatment is pretty strong and will often show a visible impact on the soybean plants with what Bayer is referring to as a “halo” effect on the cotyledon leaves. This hasn’t appeared to impact yield or stands negatively.
Perhaps the biggest decision you can make if SDS is in your area is selecting the right soybean variety. Seed companies have a pretty good handle on which varieties are fairly tolerant to SDS if you’re planting a mid-Group 1 maturity soybean and later. In the earliest maturities planted in the northern Corn Belt, seed breeders just haven’t seen enough SDS to get a good idea which varieties have the highest levels of tolerance just yet.
Another theory about what may help combat SDS is to plant soybeans later because it’s caused by a disease that thrives in cool, wet soils. Work done at Iowa State University this year appears to illustrate this. Did early planting increase the severity of SDS in soybean fields? Yes, it absolutely did. However, the loss in yield from waiting to plant outweighed the loss from SDS, so planting your whole farm later in May is not recommended. The conclusion of this work is that you should plant your non-SDS fields first and your most tolerant SDS varieties first, leaving your fields with known SDS pressure and weaker varieties until last.
Finally, when you have diseases that need wet soils to thrive, improving drainage is an obvious solution. That may mean narrowing up the spacing on existing pattern tiled fields, at least in small areas where SDS has been a problem.
At the Ag PhD Agronomy Workshops in soybean country this winter, we’ll go into more depth on what you can do to protect your fields from sudden death syndrome (SDS) and capitalize on your yield potential.