Successful corn pollination is dependent upon many factors

A simple ear shake test can access kernel set shortly after pollination.

Tasseling and pollination is a critical time in the life of a corn plant. These two functions work in concert to allow the pollen to fertilize the ovule, resulting in a kernel. Pollen shed occurs over a two-week period. During that time, silks must emerge and be fertilized. Although this seems simple, there are several things that Michigan State University Extension explains can impact the success and, therefore, impact the number of kernels.

  • Moisture. Drought stress throws silking and pollination out of sync, slowing silk elongation and accelerating pollen shed.
  • Temperature. Temperatures greater than 95 degrees Fahrenheit with low relative humidity will damage exposed silks. In addition, temperatures in the mid-90s or greater will render pollen no longer viable.
  • Insects. Corn rootworm beetles feed on silks, pollen and kernels. Japanese beetles will feed on silks. Control will be dependent upon number of beetles throughout the field and the stage of pollination.
  • Hail. Hail damage at tasseling is more serious than at any other stage of development as it can lead to the complete loss of a pollen source.

Many fields began to tassel during the week of July 15, 2013, one of the hottest weeks of the 2013 growing season where temperatures hit 97 F in parts of Mid-Michigan, according to Enviro-weather. This week (week of July 22), temperatures fell to below normal and while parts of Michigan acquired needed rain, there are other areas where corn is showing drought stress. In addition, corn development is quite variable. With all this variability, is there a way to assess how successful pollination was in your corn field?

John Nielson, agronomist at Purdue University, demonstrates an Ear Shake Test to determine how many kernels have pollenated. The simple test involves selecting an ear where silks are emerged and possibly beginning to turn color on the ends, indicating the pollination period is nearly complete. Cut the butt end of the ear cross-ways, exposing the cob and the ring of kernels. Carefully slit the husks lengthwise so the husks can be gently peeled off, leaving just the silks covering the cob. Gently shake the cob, allowing the detached silks to fall. This will expose the kernels that have been pollenated.

Although there are still many factors that can impact yield, this test gives an indication of pollination success and kernel set.

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