No. 10 Article 7/June 1, 2007

Remain Vigilant for Weeds in Corn

The recent rain across portions of Illinois has brought much-needed moisture to some areas experiencing very dry soil conditions. Crops growing in dry soils will benefit from the precipitation, but weeds may also gain from the rainfall.

Many weed species have already emerged, and the recent precipitation may trigger another flush. Also, some species have yet to stage significant emergence but will likely be helped along by the precipitation. With a considerable amount of the growing season remaining, corn fields that already have received a postemergence herbicide application should continue to be monitored for additional weed emergence; be especially vigilant for those species that typically do not emerge until later in May, such as morningglory and hophornbeam copperleaf. Fields in which no soil-residual herbicide, or only a limited amount, was applied are prime candidates to experience additional weed emergence; these fields should be carefully scouted during the next week or two. If significant weed emergence occurs after the initial postemergence herbicide application, additional management strategies may be needed to reduce the potential for problems later during the season.--Aaron Hager

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