Warm temperatures moved corn crop along but also caused stress
ST. PAUL -- Frequent rainfall this spring delayed planting by at least 10 to 14 days in most of Minnesota, compared to last year; however, above-normal July temperatures caused rapid corn growth, resulting in a crop that is at a similar stage of development as last year.
An average per-acre corn yield is likely in much of the state if conditions over the next month are favorable for grain development, such as moderately warm days, comfortable night temperatures, adequate soil moisture and abundant solar radiation.
Much of the corn pollination in Minnesota occurred between July 15 and 25 this year, depending on planting date and hybrid maturity. With a general guideline of 60 days from pollination to maturity, the crop is expected to reach maturity between Sept. 15 and 25, well in advance of the first fall freeze. For most growers, this should provide sufficient time for in-field dry-down of grain prior to harvest, and for tillage prior to soil freeze-up.
For growers with full-width tillage systems who expect to plant corn after corn in 2012, an earlier corn harvest could provide the opportunity for earlier fall tillage. Earlier fall tillage generally enhances decomposition of corn residue before soil freeze-up, partially offsetting the yield reductions typical of corn-after-corn compared to corn-after-soybean.
Although the hot July temperatures helped late-planted corn catch up, the heat affected pollination and kernel abortion, or kernel loss, in many fields, even though soil moisture was generally sufficient. The most commonly reported issue has been above-normal kernel abortion at the tips of the ears. In some cases, up to 6 percent of kernels were aborted. However, with the abundant rainfall in June and July, ears in most fields were longer than normal, which should offset the above-normal kernel abortion.
There have also been some problems with pollination due to aggressive silking prior to peak pollen shed, and because unusually high humidity early and late in the day during pollination made it more difficult for anthers on the tassel to rupture and release pollen. These issues, combined with excessive rainfall after planting which delayed weed control and increased nitrogen deficiency in many fields, and localized stalk breakage from high winds in early July, have made 2011 a challenging year.
In addition, corn root systems are shallower than normal this year due to the surplus of rainfall earlier in the season. This can result in greater vulnerability to dry conditions and greater susceptibility to root lodging in strong winds.
For more educational resources on corn production in Minnesota, visit Extension's corn website at www.extension.umn.edu/corn.
Jeff Coulter is a corn agronomist with University of Minnesota Extension.