Recent research from Illinois indicates there are ways of improving fungicide efficiency, due to plant-disease concerns, without losing yield. The key appears to be making sure an adequate amount of nitrogen is applied to the corn crop.

Over the past 2 years, University of Illinois agronomists Steve Ebelhar and Carl Bradley have demonstrated the value of applying high levels of nitrogen when diseases were present in corn fields.

Fungicides Pay Off

Conducting trials at two southern locations within the state, the University of Illinois agronomists found a 10-bushel-per-acre response with fungicides when higher nitrogen rates were applied. As a result, they’re even suggesting fungicides could pay off every year regardless of disease concerns.

In addition, corn treated with higher rates of fungicides responded well with extensive disease pressure.

Ebelhar says this year’s hot, humid summer days likely represented a growing season when fungicide treatments definitely paid off.

In one trial, Headline was applied with high rates of nitrogen. In another plot, the fungicide was applied without high amounts of nitrogen.

“Headline wiped out the disease, but we saw some pretty pale-looking corn where the extra nitrogen was not applied,” he says. “With Headline and the high rates of nitrogen, we got nice, dark leaves even though there was some disease on the leaves. While the fungicide doesn’t wipe out all the diseases, it eliminates a good share of it.”

The agronomists also evaluated the effectiveness of the normal insecticide treatment with seed. The researchers felt that if the roots are protected and grow better, this should lead to higher yields, along with a need for more fertilizer to support the increased yield. They suspected that if the roots and leaves were protected for a longer period of time with fungicides, then more nitrogen might not be needed.

More Nitrogen Paid Off

The research data indicated heavier-fertilized corn plants were more effective in dealing with disease.

With an application of 180 to 200 pounds of nitrogen per acre, yields averaged around 200 bushels an acre.

“If you keep the nitrogen rates high enough and keep the corn leaves green, they don’t need to rob the carbohydrate from the stalks to produce good yields,” says Ebelhar. “The plants stay healthier for a longer period of time and the healthier stalks aren’t subject to disease.”

Ebelhar says corn plants treated with a fungicide got positive results about half the time when it came to stalk-rot damage. The most severe stalk rot occurred with the lower nitrogen rates.