In corn: borers rearing ugly heads

In the past, southwestern corn borers have been mostly limited to the Delta areas and bordering bluff counties in the state, says Larson. But in June, farmers saw a late infestation of first generation borers in the extreme northeastern part of the state in Alcorn County.

The problem with corn borers is they have only a short time period when they’re susceptible to sprays. Once they burrow into plant tissue, it’s a coverage problem for insecticides.

Mississippi has received a Section 18 exemption for Intrepid on southwestern corn borers. “We didn’t get the exemption because of a terrible outbreak. Intrepid may allow us better control, though. Intrepid may offer better residual activity so farmers can catch more of the young larvae when they hatch from egg masses,” says Larson.

The second-generation numbers for borers are picking up. “I want to offer a warning that with northeast fields showing significant numbers, the consultants and farmers need to be aware of the situation.”

For each southwestern corn borer per stalk, a plant is probably losing between 6 and 8 percent yield. The plant could also sustain stalk damage resulting in lodging or ear dropping prior to harvest.

“So, not only could a farmer lose that percentage of his grain weight, there’s also a risk of additional losses. It can be a devastating pest,” says Larson.

In Arkansas, stinkbugs appear to be the problem of the day in cornfields.

“We’re having a bunch of calls on stinkbugs in the corn. No one knows quite what to do with them,” says Extension specialist William Johnson.

The state has some “stunted up” corn from early feeding activity when corn was knee-high to waist-high, he notes. But now stinkbugs are piercing the ears.

“Most people think this won’t be a huge problem. But one of our entomologists has some chemical trials out to see if something will work ﷓ just in case,” says Johnson.

Mississippi’s Larson says he got a call from a grower in the Clarksdale area saying stinkbugs were in his corn.

“Generally, once corn reaches taselling and silking stages, its susceptibility to stinkbugs decreases considerably. There have to be numerous stinkbugs per plant to cause much damage.

“However, they can cause a lot of damage if they’re in a corn field two or three weeks before silking,” says Larson.

Stinkbugs will actually pierce a plant and inject a toxin into developing ears. That leads to a deformed ear, often termed a ‘cow horn’ effect. The affected ears are generally 6 to 8 inches long and curved.

In general, the corn crop across Mississippi looks very good, according to Larson. “I’d still like to see rain on the dryland crop for the next couple of weeks. Most of our crop should reach maturity beginning the last week of July. So there’s still some time we’ll need some moisture on the corn crop.”

Johnson is even more enthusiastic about his states’ prospects. “From what we’re seeing, this could be a banner year. The state had needed some nice rains on our crop. We got those rains in most places and some cooler weather too. As a result, I’m hearing farmers say this is the best corn crop they’ve seen.”

Just from pulling ears, Johnson says it appears that Arkansas has an abundance of 175 to 220 bushel corn. The Arkansas River valley area (which, for the most part, isn’t irrigated) should have 150 to 170 bushel corn.

“I think this will be a record crop. Our current record is 132 bushels or close to that. Not having to irrigate all hours every day, this has been a great corn growing year,” says Johnson.

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