Corn earworm moths have shown up earlier than usual and in greater numbers than in recent years across the Mississippi Delta, particularly in Mississippi and Louisiana.
Ryan Jackson is a research entomologist with the United States Department of Agriculture’s Agricultural Research Service in Stoneville, Miss. Part of his job is tracking corn earworm moths across the Cotton Belt from Virginia to Texas. Based on the moth numbers he is seeing in Mississippi, he says the chance for higher-than-normal corn earworm pressure looms large in 2010.
Jackson’s assessment is based on pheromone traps set up in 10 Mississippi Delta counties. Last year, corn earworm moth trap numbers were high — though not as high as this year.
Fortunately, he says, in 2009, the heaviest third generation of corn earworm moths — the one that does the most damage to corn — did not synchronize with the corn silking, so major crop damage to corn was averted. “We can’t necessarily count on that happening again in 2010,” Jackson warns.
Until now, corn growers in the South have more or less had to live with corn earworm damage. Use of insecticides is not economically feasible against this pest in field corn, and the proper timing of applications is difficult. By the time ear feeding is discovered, it is usually too late for control measures. Losing just three kernels per ear can equal one lost bushel per acre.
Greg Ferguson, a DeKalb brand agronomist in Mississippi, notes that this season, farmers across the South have a new defense against the corn earworm. Monsanto’s Genuity VT Triple PRO technology provides multiple modes of action against above-ground pests, including the first in-plant control of corn earworm, for improved grain quality and higher yield potential.
In large-plot trials conducted by Monsanto across the South in 2009, this new technology demonstrated a 6-bushel-per-acre yield advantage over existing Bt insect-control technologies in areas experiencing high corn earworm pressure. “The Genuity VT Triple PRO technology is much more active against the corn earworm than the first-generation Bt products,” Jackson says.
Ferguson notes that Genuity VT Triple PRO also enables Southern farmers to reduce their corn refuge from 50 percent to 20 percent, increasing whole farm yield and profit potential.
Jackson reminds farmers that the corn earworm also poses a risk to other crops. “By mid-May, we were already seeing corn earworm moths on pre-squaring cotton (as the cotton bollworm) and pre-bloom soybeans, which is quite early and very unusual,” Jackson explains. “We are also seeing high numbers in preferred wild host crops such as crimson clover.
“Corn is a big springboard for corn earworm before it moves into cotton and late planted soybeans,” Jackson adds. “It is a good idea for cotton and soybean growers to watch what that pest is doing in corn, because it’s a good indicator of what might lie ahead in the other crops.”
Multiple generations of corn earworm can invade cornfields from spring through mid-summer. The moths lay most of their eggs directly on corn silks or green leaf tissue near the ear. When the larvae hatch, they move rapidly down the silk channel to feed on the ear tips or midsection of the ear.
Jackson observes that this past winter was much colder than usual in the Mississippi Delta and that, ordinarily, a severe winter would result in reduced survival of pupae. “You would think the sustained cold weather we experienced this year would have resulted in lower trap numbers and a delay in initial corn earworm moth flights,” he explains. “Instead, we are seeing just the opposite.”
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