Perfect ‘shake test’ to assess pollination

Corn Corner: Sample each field and each hybrid to get a clear picture of pollination success.

Jul 02, 2019

What is the best way to determine if pollination was successful? I planted at least a half dozen hybrids over 2,000 acres. Should I check each field and hybrid?

The Indiana certified crop adviser panel answering this question includes Jamie Bultemeier, A&L Great Lakes Labs, Fort Wayne; Troy Jenkins, agronomist with Ceres Solutions, Rochester; and Marty Park, Great Lakes Seed Service, Rensselaer.

Bultemeier: The best way to evaluate success of pollination is an ear shake test to determine relative percentage of an ear that pollinated. Select an ear where silks have extended out the end and are visible. Carefully cut the butt by cutting across the ear. Often, it’s best to take a couple cuts to reach the base of the ear to avoid cutting off kernels.

Some people cut husks along the length of the ear to get to the ear quicker; others simply peel husk leaves back to expose kernels without disturbing silks. Hold the ear horizontal and gently shake. Silks that have pollinated fall from the ear. Remaining silks are attached to unpollinated ovules. Ears pollinate from the butt to the tip unless there’s insect clipping or other physical impedance to silk elongation. Evaluate the ovules. If they’re turning dark with silks attached, they may abort.

It’s wise to check each field and individual varieties in that field. Pollination can be impacted by planting date relative to pollination, weather, hybrid and soil conditions. Checking only one hybrid in only one field assumes that all fields containing a given hybrid experienced the same environmental conditions at pollination. In most years, that’s not a correct assumption.

Jenkins: Checking cornfields for successful pollination should be done on each field. Factors affecting pollination are: planting date variation, insect silk clipping, temperature drops prior to pollination, heat or drought during pollination, and hybrid response to other environmental conditions. Spending just a few minutes entering and checking fields by hybrid might allow you to offset pollination problems in fields yet to pollinate. Evaluating pollination success might help you realize crop potential and plan for additional crop inputs.

Late in the pollen shed period, test ears by slicing with a knife from the butt of the ear to the tip. Carefully remove the husks without detaching silks from the ear. Grab the butt of the ear and hold horizontal. Shake the ear, and silks from fertilized ovules will fall away. Silks from unfertilized ovules will remain attached. Silks from fertilized ovules will detach about two to three days after receiving pollen. Remember, if pollination is not over, you may see tip silks remaining that might still pollinate.

Park: Use the ear shake method a few days after pollination has wrapped up. Carefully cut the husks off, hold the ear by the butt and shake it. Silks will fall off developing kernels that are pollinated. Silks that hang on indicate ovules that haven’t been pollinated.

Pollination is rarely an issue with the modern hybrid blends that we plant today. If you have had some weather stress or just really want to be sure of pollination, the only way you’re going to know is by looking at each hybrid in each field, since you have different planting dates and weather conditions across your 2,000 acres.