By this point in the season, corn on droughty ground has already been harvested, or looks like its October. However, some fields still have some green left, or at least were planted later and on heavier soils. The question has been asked- will rain now and cooler weather help the corn crop?
Most agronomists say it's simply too late. With corn pollinating in mid-to-late July, and with it typically taking 55 days for grain fill, along with much hotter temperatures to speed along development, the train has left the station in most cases. Whatever was aboard before any recent relief came is likely what will arrive in your combine cab.
"If there is no green color left, then there is little or no chance to add yield," says Emerson Nafziger, University of Illinois Extension agronomist. "No green leaf area means no more photosynthesis. The factory is closed for this crop." That also applies to soybeans which are no longer green, he notes.
In early-planted fields, or in fields planted with early-maturing hybrids, shutdown at the end of the season may have been relatively normal. However, in very dry areas in Indiana and Illinois, plants died early. In many case, the kernels weren't completely filled yet as the plant shut down.
If there's still a milkline and conditions have improved, Nafziger says kernels might still be able to receive some sugars from the stalk. This assumes that the black layer, signifying physiological maturity, has not developed yet.
The kicker is that stalks in these fields have probably already been depleted of sugars anyway, he further adds. The reality is that it's doubtful if yields will increase further.
Dennis Bowman, an Extension ag specialist in central Illinois, says that this may result in low test weight in some fields this year. It's likely not going to be a year when you want to or get to brag about test weights, especially if your crop was caught up in the worst of the drought stress.One reason test weight may suffer is that kernels that develop closest to the tip, even if they're not right at the tip, will likely be smaller than normal, he adds. One of the biggest effects from dry weather and heat he's seen is excessive abortion of kernels and tip dieback. Usually, there isn't a line where one kernel aborts and the next in line is a full, plump kernel. Instead, that one that survived and escaped abortion is likely to be smaller than kernels at the base of the ear. That will make a difference when it's time to check test weight this fall.