Corn is in various stages of pollination and at differing degrees of stress across the country. The question most are wondering is if true relief comes now, is it too late for corn?
The answer may range from absolutely yes to no to somewhere in between. Here's how we see this season shaping up in the areas where drought has been a factor. Plus, excessive temperatures in late June through early July when many fields were trying to pollinate have been a factor even in areas which have reciev3ed moisture.
This information is based on conversations with Bob Nielsen, Purdue University Extension corn specialist, and on information supplied by the Purdue University Corn & Soybean Field Guide.
The first key is successful pollination vs. pollination failure. Silk clipping by insects can interrupt pollination, but that's likely not the major concern this year. However, insects shouldn't be ignored, at least not without scouting fields.
Drought stress coupled with heat stress is the most aggravating factor that causes tassel emergence and pollination to speed up while slowing silk emergence. The result is pollen falling when silks aren't there to receive it. This may be the telling factor in some fields. Corn began tasseling in hard-hit areas at three feet tall. Dave Nanda of Seed Consultants, Inc., says it's because corn switched to survival mode, trying to produce whatever it could. The problem is that when the tassels emerged, there weren't yet visible shoots in some cases, let alone silks.
Even if there are silks, drought stress may make them less receptive to receiving pollen. This can also reduce the effectiveness of pollination.
Pollen that's not viable due to drought stress and heat stress is rare. However, this is a rare year. Time will tell if degradation of pollen grains themselves was an issue.
Even if pollination occurs, the next step is developing kernels. Kernel abortion is a concern in drought-stressed years. Heat stress or soil compaction can make it worse. Some fields in hardest hit areas are suffering from all three
Excessive respiration at night caused by temperatures staying above 65 degrees during pollination can also lead to kernel abortion. This is the third year in a row for this to occur during pollination. USDA has badly over estimated yields in early estimates in both years. Some believe it's because of the respiration issue.
To review, missing the pollination nick could lead to ears only partially filled with kernels. Excessive heat could cause some kernels to abort even if they pollinate. High night-time temperatures will work against higher yields.
For some fields that may turn out to be three strikes. Time will tell.