News

Early concerns about soybean, corn diseases

A plant disease expert says whether crops emerged weeks ago or this week, farmers should watch for signs of infection.

Dr. Damen Smith with the University of Wisconsin tells Brownfield producers should scout for soybean plants that emerged and then died and wilted. “If you’re starting to see a number of those plants out there as you’re doing those stand counts and doing that scouting, that would give you an indication that you probably had either pythium or some early-season phytopthora.”

Smith says those problems are typically in heavy soils and areas that stay wet longer.  He says the warmer, dryer forecast should also help. “I think if we could pick up some heat units here, that would help. That would help push the crop along, get things out of the ground a little more, and get us through this early seed, seed rot window thing that we’re kind of keeping an eye on.”

Smith says he is concerned about pythium in soybean and corn fields, and says stand counts may help determine if replanting is necessary.

Smith says he is also getting calls from farmers about corn anthracnose spots on leaves, which he says does not automatically mean stalk integrity is at risk. “Folks think that if they see the leaf symptom now, the leaf spot, that that will lead to the stalk rot phase, and that actually isn’t the case. It turns out you can actually have some leaf spotting early in the season on the juvenile leaves of the corn plant. The plant will eventually grow out of it and be just fine.”

Smith says seeing spots doesn’t necessarily mean prepare the sprayer, especially before the V6 growth stage. “Folks often will want to do an early fungicide application for this, like around the V6 timing. We’ve never seen any economic benefit at that ultra-early timing for fungicide applications on corn so I would resist that temptation.

Smith says even when adding a low-cost fungicide to the tank mix when spraying weeds, the return on investment isn’t there with only about two more bushels in yield.  He says spraying fungicides when they won’t do much good only drives fungicide resistance, shortening the time that tool can be effective.

AUDIO: Dr. Damon Smith discusses early season corn and soybean disease concerns with Brownfield’s Larry Lee