Tips for evaluating corn hybrid demo plots
HUSK COVERAGE/EAR ANGLE. Hybrids will vary for completeness of husk coverage on the ear as well as tightness of the husk leaves around the ear. Ears protrude from the husk leaves are susceptible to insect and bird feeding. Husks that remain tight around the ear delay field drydown of the grain. Hybrids with upright ears are often associated with short shanks that may be more prone to ear and kernel rots than those ears that point down after maturity. This relationship received considerable attention in 2009 when Gibberella ear rot problems were widespread across the Eastern Corn Belt. However, we’ve observed that differences in ear “orientation” among hybrids can be strongly influenced by growing season and plant density. Also, under certain environmental conditions, some hybrids are more prone to drop ears, a major problem if harvesting is delayed.
The following are some additional points to consider during your plot evaluations:
1. Field variability alone can easily account for differences of 10 to 50 bushels per acre. Be extremely wary of strip plots that are not replicated, or only have "check" or "tester" hybrids inserted between every 5 to 10 hybrids. The best test plots are replicated (with all hybrids replicated at least three times).
2. Don't put much stock in results from ONE LOCATION AND ONE YEAR, even if the trial is well run and reliable. This is especially important this year given the tremendous variability in growing conditions (e.g. planting dates) and crop performance across the state. Don't overemphasize results from ONE TYPE OF TRIAL. Use data and observations from university trials, local demonstration plots, and then your own on-farm trials to look for consistent trends.
3. Initial appearances can be deceiving, especially visual assessments! Use field days to make careful observations and ask questions, but reserve decisions concerning hybrid selection until you've seen performance results.
4. Walk into plots and check plant populations. Hybrids with large ears or two ears/plant may have thin stands.
5. Break ears in two to check relative kernel development of different hybrids. Use kernel milk line development to compare relative maturity of hybrids if hybrids have not yet reached black layer. Hybrids that look most healthy and green may be more immature than others. Don't confuse good late season plant health ("stay green") with late maturity.
6. Differences in standability will not show up until later in the season and/or until after a windstorm. Pinch or split the lower stalk to see whether the stalk pith is beginning to rot.
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