Corn earworm migration possibilities are on the increase going into next week across a good portion of the western and central corn-growing region as a fairly strong low pressure system and attendant cold front move through the area. Moderate risks are already in place from Nebraska and South Dakota east into Wisconsin and Illinois for the early-middle portions of next week.
In the near term, a low pressure system and cold front will push through much of the Midwest over the next 24-48 hours. Mainly light southerly winds may result in some isolated corn earworm flights overnight tonight and into tomorrow morning in Missouri, Iowa, southeast Minnesota, southern Wisconsin, Illinois, and Indiana as well as portions of southern Michigan and western Ohio. The system pushes east into the eastern Midwest later Saturday into Sunday as high pressure drops south into the Plains and Midwest so no risk is predicted due to a lack of southerly winds.
The main focus in the forecast comes next week as the weather pattern shifts to a westerly or southwesterly flow and southerly winds return to much of the western and central corn-growing region. A fairly widespread corn earworm flight may occur from the early to middle portions of next week as persistent south to southwest winds from source regions in Kansas and Oklahoma blow north. Precipitation is also expected and may serve as insect drop zone regions. Moderate risks are already in place across much of the western corn-growing region (especially west of the Mississippi River) with the potential for high risks a distinct possibility once forecast confidence increases by early next week. Growers in these areas should be on the alert for new moth flights next week.