Corn School: Check The Whorl To Determine Yield Potential


What impact can fungicide have on corn that’s suffering through the dry Ontario summer?

It all depends on your crop’s yield potential, explains BASF technical development specialist Rob Miller. Quite simply, fungicide applications are designed to protect yield potential throughout the grain fill period. Maintaining healthy plants that stay green allows for a greater amount of yield potential to be realized when the combine rolls at harvest.

In this episode of RealAgriculture’s Corn School, Miller evaluates corn plants at BASF’s Maryhill, Ontario research farm and offers tips on how growers can assess the yield potential of their own cornfields as fungicide application timing approaches. With less than half an inch of moisture from late May to July 1, the Maryhill corn crop is holding up pretty well.

“If the corn plant is uncurling or unfolding at night that’s a positive sign,” says Miller who explains that yield potential really starts to diminish when leaves remain curled throughout the evening.

Miller says an easy way to determine the impact of dry conditions is to reach into a corn plant and pull out the whorl. “As you unroll the leaves you should notice a fair bit of moisture that is beading off the plant. If that’s the case, the plant still has significant yield potential and would benefit from a fungicide application.”

With the dry weather, growers have seen little evidence of disease but that can change, says Miller. “Historically, northern corn leaf blight and eyespot don’t show up until later in August. So if we get a couple of inches of rain … or just a little bit of moisture we might start to see those diseases show up.”

Miller also notes: “in dry weather, we typically see more common rust. We saw that in the wheat crop … so potentially we could see more leaf rust in corn this year.”

Even in a dry year, optimum fungicide timing is still early tassel to full tassel. Twelve years of research shows that this timing consistently provides the best return on fungicide investment, says Miller.

Click here for more Corn School episodes.

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