Integrated Crop Management News

Document Type


Publication Date



Several articles have appeared in the ICM News describing the effects of recent weather on corn, including temperature effects on corn emergence,hard freeze effects on emerged corn, and corn tolerance to herbicides. Another issue involves determining the correct growth stage of corn that was damaged by the May 9 frost event. Herbicide labels typically restrict application either by corn height or leaf number. Leaf number is considered more accurate than height since it better represents the physiological stage of corn development (although this is muddied since people count leaves differently and it isn’t always clear on herbicide labels which counting method is used). See pages 4 to 9 in the Corn Field Guide for information on the leaf-collar corn staging system.

Copyright Owner

Iowa State University



File Format





The Iowa State University Digital Repository provides access to Integrated Crop Management News for historical purposes only. Users are hereby notified that the content may be inaccurate, out of date, incomplete and/or may not meet the needs and requirements of the user. Users should make their own assessment of the information and whether it is suitable for their intended purpose. For current information on integrated crop management from Iowa State University Extension and Outreach, please visit