Get to the bottom of soybean diseases

WATERVILLE, Ohio — If your soybeans are turning yellow, you’re not alone.

From the road the plants may look white, but that’s just flipped over leaves.

If you look closely, you’ll notice distinct leaf and vein patterns. The veins remain green, and the yellow in between the veins may — or may not — continue to fade to brown.

Mike Hannewald, field agronomist at Beck’s, shared tips in a YouTube video, helping farmers identify which plant disease could be the culprit.

“If it’s just green and yellow with no brown, it could be a manganese deficiency,” he said. “But the brown is an indicator of disease.

“There are three potential diseases with those leaf symptoms. Just by looking at the leaves, we can’t always tell the difference, so we need to look a little bit deeper.”

Using a shovel to dig it up, farmers can examine the plant more closely.

“If you look at the center of the stem and compare it to either side, if the center (or pith) is a distinct brown color, that indicates brown stem rot,” Hannewald said.

“If the pith is clear, but the sides (or cortex) are discolored with some brown, that is most likely sudden death syndrome.”

A newer disease — red crown rot — has progressed through Illinois and Indiana, as well.

“It can also have discoloration in the cortex,” Hannewald said. “You look one step further for some very small, reddish orange spots on the lower stem.

“Those orange fruiting bodies are critical to identifying red crown rot. If you see or suspect it, definitely let someone know at Beck’s or a local Extension office. It’s something we want to track.”

Regardless of which of those three diseases you’re looking at, it’s unfortunately too late to fix the problem.

“No foliar fungicide is going to make a difference, because all of these are soilborne funguses, and they’ve all infected early in the season,” Hannewald said.

“The best thing we can do at this point is make note of it and use that to guide our decisions for next year. We can look at our variety selection to see which varieties have more or less tolerance towards sudden death syndrome and choose accordingly, or we can also look at our seed treatments.

“We offer Escalate at Beck’s, which has Victrato, which is a Syngenta product, as a component. Victrato is very good with sudden death syndrome, helps with nematode and is currently the best on the market for red crown rot.”