Check Drought-stressed Ears For Corn Yield Potential

Drought stress makes it crucial to assess pollination now and decide whether to wait for grain harvest or salvage for silage.

Published on: Jul 23, 2012

At a field day last Wednesday, Penn State Extension Corn Agronomist Greg Roth said in wry humor: "This year's disaster is drought. And this week's disaster advice is on assessing corn pollination."

With the soaring price of corn and strain on forage inventories, assessing corn pollination right now is hugely important. With pollination already well ahead of schedule, now's the time to assess corn fields for their potential yield and any need to salvage severely drought-stricken fields for silage. In many areas of the Northeast, harvest of drought-damaged corn will get underway this week.

How to assess pollination and yield

COUNT YOUR SILKS: Silks still attached to a kernel site means that the kernel hasnt been pollinated, says Roth.
COUNT YOUR SILKS: Silks still attached to a kernel site means that the kernel hasn't been pollinated, says Roth.

Gently pull back husk leaves of some representative corn ears and shake the ear. Those silks that remain attached to the ear are likely not pollinated. Often they'll be on the ear tip where the last silks to emerge were attached. In severe situations, non-pollinated kernels may be scattered throughout the ear or concentrated on ear undersides.

Next, count and record the number of rows and the kernels per row, again on a number of representative stalks. Multiply the rows by the kernels per row to determine the kernels per ear.

Then multiply the kernels per ear by the plants per acre to determine kernels per acre. Then divide this by 90,000 to estimate the potential yield in bushels per acre.

Estimating silage yield is trickier, concedes Roth. "But we often divide the yield by 6.5 to 7.0 to get a ball park estimate of the yield in tons per acre at 65% moisture. This is quite variable though, since the bushels/ton can vary, especially in years like this when the plants may be shorter than normal."

A bit of good news

In Pennsylvania, agronomists have generally been surprised at the success of pollination in a lot of early corn. "This tells us that we have significant recovery potential from the early drought stress in some fields," says Roth.

Getting a good estimate early of the yield potential provides some idea of potential for marketing the crop as grain or for future forage needs. Note the maturity stage now, though.

Corn is ready to chop 35 to 45 days following silking. That means with the early maturity of some corn this year, silage harvest will be exceptionally early. And chopping that silage at peak forage quality will be hugely critical this year.