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Scout Diseases All Season Long

April 25, 2018
This agronomic image shows a planting field in the Midwest covered in snow.

Planting delays in Midwest caused by cold weather.

To follow up on our earlier post about delayed planting in the Midwest, here are a few considerations for disease control specific to late-planted corn, soybeans and wheat for you to keep in mind while waiting for temperatures to rise.

Crops planted later in the season or slow to come out of dormancy may be more susceptible to infection at earlier growth stages from diseases such as Northern corn leaf blight, gray leaf spot and Southern rust in corn, as well as white mold and frogeye leaf spot in soybeans and stripe rust in wheat. Each of these diseases have the potential to cause significant yield loss. To combat this threat, it’s important to identify diseases early and apply a fungicide if needed. Below are symptoms to look for when scouting for the more common corn and soybean diseases.


  • Northern corn leaf blight: Purdue University recommends looking for long, tan or gray leaf lesions ranging from 1 to 7” long.
  • Southern rust: Iowa State University says to look for small, circular or oval pustules on the upper leaf surface when scouting for Southern rust. They are usually densely scattered over the leaf surface and spores are orange when they erupt from the pustule. The best time to scout for Southern rust is VT through R5, but scouting should begin once temperatures reach the mid-70s to 80s.


  • Frogeye leaf spot: University of Minnesota says this disease can cause severe defoliation during warm, humid weather. You should scout leaves for signs of frogeye leaf spot, although it can occasionally occur on stems, pods and seeds. Frogeye leaf spot can be identified by red/brown or purple rings surrounding a round brown spot.
  • White mold: The fungus that causes white mold thrives in the soil and lower stems when the environment is humid. Penn State University recommends you look for white tufts of fungus on the lower canopy. Ultimately, hard, black overwintering structures form that can survive in the soil for many years.


  • Stripe rust: Stripe rust has already been spotted across several states, so what should you be looking for? University of Nebraska says early stages of strip rust appear as small, yellow pustules that run parallel with leaf veins. If left untreated, long, linear streaks will eventually develop.

If you find foliar disease in your fields and confirm that a fungicide application is necessary, we recommend Trivapro® fungicide. Trivapro is the hardest-working, longest-lasting broad-spectrum fungicide available for corn, soybeans and wheat. Trivapro provides preventive and curative disease control and residual control that lasts late into the season. Trials comparing 1 application of Trivapro at R1 in corn and R3 in soybeans have shown stronger residual control, higher yields and ultimately, better ROI than competitive 1-pass and 2-pass programs.

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