EDITOR’S NOTE: Tyler Steinkamp is an Iowa-based agronomist for WinField
Pollination is an essential part of crop progress in cornfields. Typically, pollination occurs over a 10-day period, so when it comes to healthy crop development, every moment counts. Perhaps one of the most important factors in fertilization are corn silks, which pollinate corn kernels. Corn silks grow 1 to 1.5 inches each day. Each silk is attached to (and pollinates) a kernel, so establishing strong silks right away is essential.
PLANT NUTRITION: Moving into the next couple of weeks, farmers are encouraged to take tissue samples to identify their crop’s need for micronutrients. Pollination and kernel formation are other factors to keep an eye on in corn fields.
As a corn grower, how can you tell if your crop is pollinating well? First, take a walk through your fields. You can tell if corn is pollinating well by removing an ear and peeling back the corn husk. If silks drop off of the kernels, the plant is pollinating well.
What if your crop isn’t pollinating well? Here are some of the key factors affecting crop pollination and how you can manage these factors to maximize yield potential.
Weather plays a big role in determining silking success
Silks are primarily composed of water, so hot, humid weather is best for silk development. Low humidity levels or dry, cool weather can compromise silk formation and hurt the pollination process. Currently, weather patterns in Iowa are optimal for silk formation. However, changes in weather, even after pollination and fertilization, can hurt a farmer’s crop.
Luckily, the storms that moved through the Midwest last week did not affect pollination. Successful pollination can be hindered if severe storms, including heavy winds or hail, lay corn plants down during the pollination phase. In these situations, the pollen essentially all gathers on one side of the ear, resulting in one side without developed kernels. This is commonly referred to as “zipper ear.”
Insects and diseases also affect silking and pollination
Farmers should also be on the lookout for insect and disease pressure during the 10-day window when corn pollinates. Corn rootworm beetles and Japanese beetles chew and clip corn silks, preventing proper pollination. Iowa fields are at risk for both of these pests this year due to hot and humid conditions.
This is also a good time for diseases, which tend to grow deeper in the canopy. While warm, humid weather is good for silk development, it also harbors a perfect environment for diseases such as gray leaf spot. When scouting cornfields look for the rectangular lesions, signifying symptoms of this disease.
Managing corn for successful pollination
During tasseling is the best time for making applications in cornfields. At this time, you can apply both fungicides and micronutrients to decrease disease pressure and increase the chance of successful pollination and fertilization. While the opportunity has passed to correct macronutrient deficiencies, micronutrients such as boron and zinc can be useful for corn crops. Boron helps transfer sugar throughout the plant and zinc promotes formation of kernels.
Overall, watch fields carefully during pollination, especially corn-on-corn fields. Farmers should pay attention to the crops’ response to fungicides and other limiting yield factors. The biggest factor determining pollination success is always weather, but monitoring insect and disease pressure and supporting plants with micronutrients will help set crops up for success.
Take tissue samples of crop plants, monitor nutrient needs
Moving into the next couple of weeks, Steinkamp encourages farmers to take tissue samples to identify the state of their crop’s nutrition. The next growth stages are optimal times to make applications of micronutrients. Micronutrient applications on corn, such as applying boron and zinc, are key at this stage to help in kernel development, to transfer sugars throughout the plant and to encourage healthy pollination.
For soybeans, Boron and manganese will be important for chlorophyll development and sugar distribution. Now is also a good time to watch for corn rootworm beetle and Japanese beetles in cornfields, as these insects can hinder pollination.