Insects, Disease and Fertility: Keep an Eye on These Three Things for Successful Corn Pollination

Once your crop is in the ground, the focus should shift to reducing or eliminating yield-limiting stressors in the field. Insects can clip silks and reduce the number of fertilized kernels. Disease pressure can reduce photosynthesis thus reducing yield. And a lack of fertility can stunt growth and keep plants from making the most of their yield potential.


Insects that pose the biggest threat are Japanese beetles and corn rootworm beetles. These pests rob yield by clipping newly emerged silks in search of fresh pollen. The threshold for treatment is when silks are clipped to 0.5 inches or less and pollination is less than 50% complete. Alternatively, five rootworm beetles per plant, or three Japanese beetles per plant, would warrant considering treatment.

Read this next: Three Insects That Can Destroy Young Corn Plants (4 min)

Disease pressure

Applying a fungicide doesn’t contribute to yield, but it can protect yield potential. If disease pressure is anticipated in your field, you may want to consider a fungicide application. You’ll need to weigh the options of grain prices, application costs and level of disease pressure when determining if a fungicide application makes sense. Check your hybrid disease ratings as well!  Consider a fungicide treatment if a fungal disease is present on the third leaf below the ear leaf or higher on 50% plants at tasseling.

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In a year when excessive rainfall may have caused higher-than-normal nutrient loss, in-season soil testing or tissue samples will be time and money well spent; they can be important tools in re-calibrating your in-season management decisions.

Nitrogen and potassium demand peaks at flowering. Close to 65% and 75% (respectively) of a corn crop’s fertilizer need is taken up just prior to VT/R1. Ensuring that corn is adequately fed N and K early in the growing season is important for establishing the baseline of yield potential prior to flowering. If time and money permits, consider a mid-season banding of N prior to tasseling to correct any N deficiencies.

We’ve had many challenges just getting the crop in the ground this year, most of them outside of anyone's control. Taking a few moments to consider these factors in your management decisions may help protect the yield potential you have, and along with it, your bottom line.

Read this next: How Does Late-Plated Corn Change the Way You Address Pest and Disease Pressures (6 min)

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