The Alabama Cooperative Extension System entomologists are warning growers about the soybean looper, a serious pest that whose numbers are higher than average this year.
Scouting efforts show infestations are worst in south and central Alabama, as the moths grow rapidly along the Gulf Coast. Extension entomologists Dr. Ron Smith and Dr. Tim Reed encourage farmers to scout their soybean fields diligently. Some growers have already begun adding insecticides to their fungicide sprays.
“The occurrence of soybean loopers is widespread in soybean fields in south and central Alabama at this time,” Smith said. “With widespread pest pressure, if a grower does not have a commercial scout, it is important to actively look for soybean loopers themselves.”
The larvae feed on foliage, usually starting on the lower half of the plant canopy, moving upward over time. Reed says scouts should sweep nets into the lower half of the canopy to get the most accurate results. He also warns that loopers are more difficult to dislodge than other caterpillars.
“Early on, farmers will see leaves with a window pane effect,” Reed said. “The very small soybean looper larvae eat only the green portion of the leaf leaving behind the transparent cuticle layer. As larvae mature, they become more aggressive feeders and once soybean loopers begin feeding on the upper canopy, they can soon consume more than 50 percent of the foliage when numbers are high.”
Smith said soybean loopers are the most expensive pest to control. While there is more than one option, there are a limited number of control options available for soybean loopers—ranging from less than $10 per acre to nearly $20 per acre. Intrepid, Intrepid Edge, Belt, Besiege, Prevathon and Steward are the only four products available to farmers for soybean looper control.