Weather conditions across the Corn Belt this year are giving entomologists reason to believe that black cutworm (BCW) damage is still possible this season. In spite of wet weather conditions, recently planted or replanted corn could be vulnerable to BCW damage.
BCW is the most damaging cutworm species to seedling corn, and larval activity has already been reported in certain areas of the Midwest. Data from several universities has been variable, but indicated large captures of BCW for selected trap locations in Illinois, Iowa and Missouri.
“Some of the counties in Missouri had a predicted cutting date in the first or second week of June and because of the late planting in these areas, the predicted cutting date could coincide with small corn this year,” says Phil Harms, Western account manager for HERCULEX® traits and germplasm.
Typically, larvae sever plants from their roots, near the soil line, thereby reducing crop stands and lowering yield. Corn plants younger than the four-leaf stage are the most susceptible to damage. Therefore, late corn plantings and re-plants due to flooding are at a high risk. However, larvae can also bore into the base of larger corn plants, killing the growing point.
Traditional control programs include granular insecticide applications, seed-applied insecticides, scouting and rescue spray programs. Seed-applied insecticide performance decreases with larger larvae, and soil-applied insecticides are not always successful either. Early scouting of fields is the only way to determine if a cutting problem exists, but it does not always catch BCW, because larvae often burrow into the soil during the day and older cutworm larvae feed on the stem underground.
“Because BCW outbreaks in the Northern states are highly unpredictable and dependent on multiple factors — such as weather patterns, timing of corn planting and environmental conditions — many growers are adopting a preventive approach by planting corn hybrids with HERCULEX Insect Protection,” says Ed King, technology transfer leader for Dow AgroSciences. “Corn hybrids with HERCULEX I and HERCULEX XTRA are the only hybrids with in-plant traits that provide immediate protection from BCW.”
“The best prevention method is the planting of a hybrid with HERCULEX technology in it,” says Marlin Rice, entomology professor with Iowa State University extension. “The amount of cutting in a HERCULEX hybrid is greatly reduced, but it is not eliminated. There is still a need for a grower to scout the field.”
With the high price of seed corn and expected returns on corn greater than average, the economic threshold of corn is also lower.
“If the threshold’s lower, the value of planting HERCULEX is greater,” says Harms. “With black cutworm, just a few is an indication of concern. Any type of pressure can coincide with substantial economic loss.”
Dow AgroSciences LLC, based in Indianapolis, Indiana, USA, is a top-tier agricultural company that combines the power of science and technology with the “Human Element” to constantly improve what is essential to human progress. Dow AgroSciences provides innovative technologies for crop protection, pest and vegetation management, seeds, traits, and agricultural biotechnology to serve the world’s growing population. Global sales for Dow AgroSciences, a wholly owned subsidiary of The Dow Chemical Company, are $3.8 billion. Learn more at www.dowagro.com.