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Crop disease specialist zeroes in on fungicide application timing

Crop disease specialist zeroes in on fungicide application timing
Here's insight if you're wondering if you applied fungicide on corn too early or too late.

Kiersten Wise is concerned some may have left valuable bushels on the table this year because they waited too late to make fungicide applications on corn. She has the results of a one-year test, and is repeating the test to verify what she believes could be an important way to pick up extra dollars next season.

Related: Spraying Foliar Fungicide Can Aid Corn Health

In recent years several agronomists and consultants have talked about making fungicide applications at brown silk. Wise says that may be too late to capture the most economic benefit from the application.

Apply earlier: Kiersten Wise believes that fungicides, when needed for corn, should be applied around tasseling, or at what is called complete pollination, rather than waiting for silks to turn brown.

It's also possible to be pressured by a dealer or applicator to apply too early. Not all fungicide applications can be made at once since several are made through aerial application.

"Our results indicate that you increase yield the most if you apply earlier than brown silk," says Wise, Purdue University Extension disease specialist. The difference can be the difference between profit and loss.

She is urging farmers to shoot for applying fungicides when you have decided they are needed by the time what Bob Nielsen calls "complete pollination" is reached. The Purdue corn specialist defines that as when you pull back husks and most silks fall off, indicating pollination has occurred. Silks are not yet turning brown at that point.

Some of the recommendations to wait until brown silk grew out of Nielsen's 2007 discovery of arrested ear development that was linked to fungicide applications. However, it turns out that the arrested development was likely tied to adding a surfactant with the fungicide application. Check fungicide labels to see what can and can't be applied with the fungicide.

Related: Companies still say fungicides will pay their way for corn

Nielsen notes that brown silk does not occur until about nine days after pollination in most cases. Wise says that is simply too late to receive the most benefit of a fungicide application when a fungicide is needed. She is making a concerted effort to get farmers to move the application time up next season.

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