As the growing season's final turn approaches, Arkansas and Mississippi corn crops look to finish in a solid position. Over the last several months, small, yield-sapping hindrances have kept the crops from being outstanding.
“The overall health of our crop is good,” says Jason Kelley, Arkansas Extension corn and grain sorghum specialist. “But all the wet, cool weather allowed some problems to develop.”
In Mississippi, Erick Larson says corn is experiencing several diseases promoted by wet weather in June. “A few diseases are working our corn over,” says the Extension corn specialist.
“The main abnormal thing we're seeing is northern corn leaf blight and southern corn leaf blight. We're finding the diseases in fields all across the state. Some hybrids are quite susceptible to the diseases. Leaves are dying prematurely, which will limit the weight of kernels as they fill out. That, in turn, limits yield.”
In some areas of Arkansas (a rain target for three weeks during June), reports of ears not filling out are common. “It seemed to rain every day, and the sun didn't shine,” says Kelley. “It looks like some plants were pushed too hard. There wasn't enough energy or photosynthesis to fill out the end of ears. Many times, the ear tips don't have kernels on them anyway. This year, though, some ears are only a quarter filled.”
Kelley, speaking from a Lonoke County, Ark., corn field, said “some good-sized ears have the top inch unfilled; about half-way down the ear, kernels are only a quarter filled. Those kernels are lost, there's nothing to be done this late.”
How severe is the problem? “It will probably be a 5 percent to 10 percent yield loss,” says Kelley.
In Mississippi, there's a wide range of corn maturity. “Some fields will be harvested next week,” says Larson. “Some farmers are irrigating this week and will continue irrigating next week — those fields are around 20 days from maturity.”
Since mid-June, common rust (similar to leaf rust in wheat) has shown up in a lot of Arkansas fields. The rust, a vigorous traveler, is found state-wide.
“It's worse than it has been in recent years,” says Kelley. “Most of our corn is far enough along that this rust won't affect yield, though. The plants should outrun the rust, and fungicide applications probably won't pay for themselves.”
Kelley has gotten reports of corn borers. Some conventional test plots around Marianna, Ark., have very high levels of the pest.
At mid-July, irrigation was about to end for most Arkansas corn. “If you're working furrow-irrigated corn, check the starch layer,” says Kelley. “Producers can split a kernel in half. If a hard starch layer has formed at least halfway down the kernel and the field has had good moisture, the crop should make it through to physical maturity. Much of our corn is right at that stage. By (the third week of July), the vast majority of our corn should be at irrigation termination.
“As warm as (mid-July) has been, some corn should be ready for harvest by the first week of August.”
Arkansas' grain sorghum crop looks “very good,” says Kelley. Sorghum acreage (at 95,000 acres) is down by about half from last year.
“Great soybean prices took away milo acres. Regardless, the rains have been ideal for our sorghum. Some later-planted fields are just now heading out.” In those fields, producers need to watch for sorghum midge, a pest that lays eggs inside flowering grain sorghum. “That's the only time it will affect the crop. Eggs will hatch and the larva feed on developing seeds, leaving portions of the head blank. From the road, midge damage looks like birds have been feeding.”
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