Corn Illustrated Plot Offers Surprises

Consultant says time to help yield winding down.

Walking through the hand-planted plots at the Corn Illustrated test site near Edinburgh, Ind., mid-week a week ago, surprises awaited, compared to a visit there less than two weeks ago. All surprises aren't good, either.

Nearly 60 hybrids are planted in the first few ranges, and Dave Nanda, Corn Illustrated consultant and president, Bird Hybrids, Tiffin, Ohio, plus the farmer, Jim Facemire, and Farm Progress editor Tom J. Bechman, rated each one on total package, including ability to handle stress and disease levels, given the conditions and maturity differences. Hybrids ranged from 95 days to 119 days in maturity.

The threesome rated the plots from 1-9, with 1 being the highest rating possible and 9 the lowest. Ratings assigned varied from 2, meaning the hybrid was holding together fairly well, and was one Facemire might want a closer look at for his own farm use, and a 6, assigned to a couple of hybrids that weren't making the grade.

The grade is fairly steep, since the plots have received about 4.5 inches of rain since May 1, and there is only three feet of loam and clay loam soil over pure sand and gravel, with no irrigation at this location. What's more, that precipitation came in nearly 30 rain events, with only one more than an inch and only one next biggest one barely a half-inch. That's not the recipe for high corn yields, to say the least.

"Differences between hybrids are becoming evident now," Nanda says. "Besides how they hold up to stress, some are now showing more susceptibility to disease than others. Even though it is still mostly dry, gray leaf spot has started appearing on some hybrids, especially early-season numbers, which tend to be more prone to disease anyway. However, some of the later hybrids are still fairly clean, especially on the upper leaves at and above the ear leaf."

With pollination over and most corn dented in the plot, disease now won't likely have much if any impact on most hybrids, Nanda says. But continued heat and dry weather could. Especially in the corn in the field that's not part of the plot, the 110-day hybrid from a competitor is already shutting down, Nanda notes. Many ears are hanging over. That field was planted April 30. The corn in the actual hand-planted plots and nitrogen test were planted May 1.

"Even a rain now won't help it a lot," Nanda notes. "We sliced open stalk tissue, and it's good- the plumbing is still there. But with the ears falling over, it will be tougher to get sugars into the ear even if it did rain now."

Nanda suspects that low test weight will result from such early die-off and shut-down. That's why even though the standard yield formula was still kicking out numbers like 150 bushels per acre for that hybrid, Nanda believes 120 is much closer. That would be a 20% reduction from the estimate in the formula, not uncommon in a year when things go south toward the end of the season and impact final kernel size and starch content.

However, Facemire says his normal experience after 30 years on drouthy soils is that drought- impacted corn often has a higher test weight. The explanation he's always received is that kernels are smaller, but packed tightly together, he noted.

Time will tell. What's most striking is how quickly these changes are taking place. Corn in the field surrounding the plot went from green and helahty, with kernels just developing, to ears falling over, the milk line dropping, and a brown layer already developing at the end of some kernels. The brown layer indicates that black layer formation isn't too far away, Nanda notes. Once black layer occurs, the crop can no longer send nutrients into the kernels. Bottom line is rain now won't greatly improve prospects for what's already in the field.


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