E. Indiana and Ohio Water Tolerance Can Lead To Yellowing Soybeans
Although soybeans appear to be improving, there are still some areas where soybeans are staying yellow. Most of this yellowing has to do with water tolerance. In the picture below (on the left) the soybeans in the forefront are yellow (the wettest area) and as the field slopes up the soybeans turn green. As a reminder, soybean nodules need oxygen to breathe and as long as soils stay saturated it is difficult for nodules to produce nitrogen.
With the saturated soils there is more root diseases. In the past week I have noticed more fields with either Rhizoctonia or Fusarium in the roots. The roots with these diseases are not producing many nodules. In fact, I have noticed some SDS (which is caused by Fusarium) starting to form on some varieties (picture to the right below). SDS symptoms usually occur later in the year, but if it shows up earlier this year it will have more of a yield impact. Fungicides will not help to control SDS. There are varietal differences and from what I can tell this year it is based on root health.