We are fast approaching the early ear formation stage with our earliest planted corn. This is the time when stinkbugs do the most significant damage to corn. Early ear formation occurs about 10-12 days before silking, and is the stage when the ear shoot is less than ¾ inch long. In fact, you will not see the tiny ear shoot on the plant unless you pull back the leaf sheaf. Stinkbug damage at this time will result in ears being aborted or severely deformed. The deformed ears are C-shaped and are often called banana ears or cow horn ears. Note stinkbug damaged ears below. The direction of the curve is the side of the ear in which the damage occurred. Growers with corn fields located close to wheat fields or any small grains should especially be prepared to scout, as stinkbugs will migrate from maturing small grains into green corn. Also, fields located close to pine plantations often experience severe stinkbug damage as stinkbugs will over-winter under the bark of pine trees. We typically see more stinkbug damage in south Alabama and the Florida panhandle than north Alabama, but I would still encourage growers in north Alabama to scout their corn for stinkbugs. Pyrethroids work well on the green species while an organophosphate material, such methyl parathion, works best on the brown species. Auburn University recommends treatment when 5 percent of the plants have stinkbugs during the early ear formation stage. Be still when scouting, as stinkbugs will often try to hide behind the stalk.
By: Rob Duffield, Area Agronomist, Pioneer "Walking Your Fields Newsletter"
May 7, 2012