"Cornfusion" in the corn field
What can you tell about the performance of a particular corn hybrid by looking at it in the field? Unfortunately, not a heck of a lot. You may be able to tell if the hybrid maturity was appropriate, assuming that it was planted and harvested at “normal” times. (“Normal” is in quotes because planting and harvesting dates differ so much from farm to farm. In this case it means what’s normal on your farm.) But to fairly evaluate maturity status you also need to know if growing season temperatures (Growing Degree Days) were near normal. It’s hard to make accurate judgments on maturity — or anything else, for that matter — following very unusual growing seasons. Like this one, for instance! However, don’t underestimate the importance of corn hybrid selection from a relative maturity standpoint since this has a huge impact on silage yield and quality.
What you cannot do is determine if the hybrid in one field is reliably better than a hybrid in another field. Hybrid A may be higher yielding, but is it because it’s genetically superior to Hybrid B, or because the soil in that field was better, or because the field was planted at a more opportune time? What was the insect population in the two fields? Was there more corn rootworm damage in one of the fields? Pioneer Hi-Bred has calculated how much higher yielding one hybrid has to be than another, even when growing side-by-side in the same field, for a single (non-replicated) comparison to be reliable. The yield difference is large enough that it should discourage most such comparisons. In fact, the Pioneer data suggests that about 20 side-by-side comparisons would be needed to provide reliable data. Over the years I’ve looked at dozens of non-replicated corn hybrid “trials” planted by seed company representatives, including some at Miner Institute. These are really just demonstrations, and are entertaining as long as you don’t make seed purchase decisions based solely on what you see there.
Standability comparisons may be valid, especially if two hybrids of similar maturity are growing in the same field and at the same population. But if one hybrid lodged more than the other, what was the reason? Did the corn root lodge (corn rootworms?), break off partway down the stalk (European corn borers?), or was the problem stalk rot? BMR hybrids have a reputation for lodging but I’m not sure how well-earned this reputation is providing the crop is harvested at 32-35% DM. Because BMR hybrids are lower in lignin they will bend over under some stress conditions, but often they’re still able to be picked up by harvest equipment. We have reliable standability data from university trials when the hybrids are harvested for grain, but little information — and absolutely no university trial data — on lodging when the crop is harvested for silage. However, Cornell University’s Bill Cox has said that the reason he doesn’t report lodging data is because lodging isn’t a problem in any of Cornell’s corn silage trials, including BMR hybrids. And as he correctly points out, why spend the time and money to collect and analyze data when it will yield nothing of value?
Plant breeders have done such a great job of improving standability in corn hybrids that lodging is seldom a problem except during very unusual events (such as tropical storms!). How times have changed: I’m old enough to remember Pride 5, a 90-day corn hybrid that was high-yielding for its time (which was the 1960s) but didn’t stand worth a darn. Farmers loved this hybrid because of its yield and good ear-to-stalk ratio, but were so worried about its standability that they would sometimes plant a field to Pride 5 only after planting the guard rows to a better-standing hybrid such as Penn 290 or a slighter later hybrid, Cornell M-3. Alas, the guard rows would stand up just fine but time and time again the Pride 5 would lodge!
Editor's note: This article first appeared in the October 2011 issue of the Miner Institute's Farm Report.
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