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Consider potential disease pressures in making fungicide decisions

Corn is starting to tassel in the Midwest, and that means the time to apply fungicides -- to both corn and soybeans -- is nearly upon us.

You may have made the decision to use fungicides this year, but have you chosen the right ones? Picking the right specific fungicides -- and applying it where it's needed, but not where it isn't needed -- is more important than some may think, says Iowa State University Extension plant pathologist Daren Mueller.

"If your mind is already made up to apply fungicides to corn or soybeans, then try two simple IPM (Integrated pest management) approaches to select which fields get fungicides," Mueller says.

First, when determining where to apply fungicides, look for the greatest disease pressure, Mueller advises. Both private companies and universities typically have data on an array of fungicide products and which ones are most effective for the disease pressures you may be facing.

"Target fields that are planted to a susceptible hybrid or cultivar and have disease present at the time of application," Mueller says.

This year, Mueller adds foliar diseases have been more prevalent. Diseases like brown spot, bacterial blight, frogeye leaf spot an Cercospora leaf blight have been seen on wider bases than in past years.

Base the product you apply, Mueller adds, on what disesases you have seen in your fields, as well as the yields you expect. But, don't expect a fungicide application to recover any yields you may have already lost because of poor environmental conditions.

"Selection of the fungicide product should be based the fungal diseases that are present. While triazoles are a bit more effective against soybean rust (not currently a threat), strobilurins are more effective against frogeye leaf spot and Cercospora leaf blight," he says. "Another important consideration, especially for this year, is yield potential. Fungicides will not recover lost yield. If you want to improve your chances of recouping your cost of fungicides, then target fields that have higher yield potential."

Corn is starting to tassel in the Midwest, and that means the time to apply fungicides -- to both corn and soybeans -- is nearly upon us.

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