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How well will corn pollinate this year?

Corn Commentary: Here’s a refresher on how to assess whether pollination was successful…

If you like surprises, stay out of your cornfields until harvest. You will either get a pleasant surprise, harvesting robust ears with every kernel filled, or an unwanted surprise, with average ears and maybe even missing kernels. However, if you don’t like nasty surprises, be sure to scout during pollination and grain fill.

Dan Quinn, Purdue Extension corn specialist, says there are more reasons to scout and monitor pollination, fertilization and grain fill than just avoiding surprises. You can determine what you did right or what went wrong, and make management assessments for next year.

“The process of pollination is one of the most critical periods for grain yield determination in corn,” Quinn says. “Successful pollination is largely determined by proper synchronization between silk elongation, tassel emergence and pollen shed.

“In certain conditions, poor pollination and kernel development can occur, which can result in significant reductions in kernel numbers and yield. Typically, one of the most common instances of poor pollination is due to delayed silk emergence, often caused by drought conditions. That can result in missing kernels at tips of ears.”

Pollination checks

Checking for pollination success is technically also checking to see if fertilization occurred properly, Quinn explains. Pollination refers to shedding of pollen from anthers in the tassel, while fertilization is the actual act of the pollen grain traveling down an individual silk and fertilizing an ovule waiting on the cob. If a kernel forms, the process is successful.

You don’t have to wait until you see kernels to determine if the process succeeded, Quinn says. Instead, you can do a low-tech “shake test.”

“Pull back shucks and hold the ear horizontally,” he explains. “Simply shake it. If silks fall, those embryos are fertilized, and kernels are forming. If silks remain attached, they’re waiting to be fertilized by pollen grains.

“If something went wrong and pollen is no longer available, silks keep growing. Extra-long silks are a sign that the ear probably didn’t get fertilized.”

Missing ‘butt’ kernels

While hot, dry weather often produces missing tip kernels, as noted, sometimes missing kernels end up on the base of the ear, where fertilization begins. “Sometimes silks emerge too early and missing kernels are observed at the base or ‘butt’ of the ear,” Quinn notes. “Many modern hybrids have improved genetics which include improved drought tolerance.

“One way these genetic improvements combat drought stress is through quicker and more vigorous silk emergence. But if growing conditions are more favorable, silk emergence can occur too quickly, which results in the earliest-emerging silks losing viability before pollen shed.

“That results in poor pollination and missing kernels at the base. Add in cooler weather, sufficient soil moisture and cloudy conditions, and if silks emerge too soon, they can become excessively long. That can cause pollination issues due to silk overlapping or shading.”

Across the rows:
Wide range in crop size becomes obvious

These reports from across the Corn Belt shed light on what’s happening in cornfields across the country:

In northeast Iowa. “We had a relatively dry week [late June], which allowed farmers to continue field operations. Corn ranges from about V2 to V7, with some at V8 for the earliest-planted fields. All of the corn and soybeans have now been planted, including replantings due to ponding issues and saturated soils. Field operations have comprised of postemerge herbicide applications in corn and soybeans, along with nitrogen applications in corn, both planned and supplemental due to excessive moisture.” — Terry Basol, Iowa State University Extension agronomist

In central Iowa. “Corn varies in stage, but much of the early-planted corn is bigger than V9. I’m receiving fewer calls about uneven corn, as it has reached nitrogen and put down roots deeper into the soil. With tar spot finds in central Iowa over the last 10 days, I’ve been getting more phone calls. It is absolutely worth scouting fields to see whether you can find any in your fields, but it is NOT yet time to make a fungicide application.” — Meaghan Anderson, Iowa State University Extension agronomist

In Illinois. “How soon corn shows moisture stress during this hot stretch will depend partly on when it was planted and planting conditions. Fields planted into wet soil which now restricts roots may not be able to reach moisture reserves deeper in the soil.” — Trent Ford, Illinois state climatologist, from discussion with Todd Gleason for FarmDoc

In Ohio. “Freeze damage occurred earlier this year at the Western Agricultural Research Station. Corn planted on March 25 sustained freeze damage between April 21 and 22, with temperatures reaching as low as 27 degrees F and temperatures lingering at 30 degrees F. Corn had extensive visual damage, and the first two leaves on most of the plants died. On June 3, the March 25-planted corn had fully recovered and was at growth stage V8. This freeze happened between V1 and V2, and the soil did not freeze, so the growing point survived. Yield data will assist in showing if there was an impact.” — Taylor Dill, C.O.R.N. newsletter from Ohio State University.

Source: https://www.farmprogress.com/corn/how-well-will-corn-pollinate-this-year-

Image: Farm Progress