Preserving Your Corn Yield Potential
Tasseling and pollination are exciting and important stages in the corn plant’s life cycle. Up to this point in time, helping the plant maximize its yield potential was the goal. After pollination, the goal becomes preservation of that yield potential.
Corn pollination occurs in a short window (7 to 10 days), so stresses during this time chip away at yield potential. The biggest risks during the pollination window are excessive heat, lack of adequate moisture, insects, and cloudy weather.
Heat stress occurs when temperatures are abnormally high – at least 95 degrees Fahrenheit. These temperatures can negatively affect silks and pollen grains during pollination. Silks can desiccate, becoming unable to receive pollen. This is masked if soil and plant moisture is adequate, so it can be hard to determine if heat or drought is the cause of reduced yields in many cases.
Beginning with the late vegetative stages and continuing through pollination, drought has an increasing level of damage through each stage. In severe cases, corn yields can be reduced by 10 percent prior to tasseling. During tasseling, drought can affect yields by 10 to 25 percent. Drought stress during pollination can reduce yields 40 to 50 percent. Normally the plant needs to be fully stressed with extensive leaf rolling for at least four days to induce the higher end of yield-loss ranges.
Silk-feeding insects normally are not an issue in North Dakota and western Minnesota, but with increasing levels of corn rootworm in the area, insects must be considered when discussing yield loss during pollination. Rootworm beetles will feed on pollen grains, which can lead to clipped silks that will not pollinate. Kernels may be lost as a result of this feeding.
Cloudy weather also plays a role in corn pollination. Long stretches of overcast skies can reduce photosynthesis, leading to abortion of recently fertilized ovules. Cloudy weather can also delay the onset of pollination. The pollination window can vary in the field but normally lasts for a week or more. Peak pollen shed lasts about four days, with an individual plant able to release over 500,000 pollen grains per day during pollination. Lack of pollen normally is not an issue since plants will produce 20,000 to 50,000 pollen grains per silk. It is usually the timing of silk emergence during pollen shed that makes the difference.
I encourage you to track the weather as well as some of these variables during pollination. If your corn’s kernel set is not ideal, you’ll be able to reference this information to zero in on the reasonable cause.
