By Roger Elmore, Department of Agronomy
Corn progress is back on track thanks to recent warm weather. This is indicated by heat unit accumulation for May 1 planting dates hovering slightly above average (107 percent of average statewide). Corn development across the state ranges from about V2 to V9 (second to ninth leaf stages) thanks to the wide range of planting dates this year.
And then thunderstorms hit on June 9 and pounded the corn; some of the thunderstorms were accompanied by severe hail. Plant growing points are still underground for corn plants at V6 (sixth leaf stage) and younger. This fact helps the plants survive early-season hail events even if the leaves are totally destroyed.
Be patient if your field has hail damage. The short-term weather forecast for warm and sunny weather plus the moisture received from the storms should encourage rapid and healthy regrowth. Plants V6 and younger should survive. Assess more developed plants carefully. The following links provide more detailed information:
- Hail injury on corn, ISU; ICM News
- Assessing corn stands for replanting, ISU; ICM News
- Replant checklist
- Evaluating hail damage to corn, University of Nebraska
Hail Industry staging systems differs
Be aware that hail industry corn staging systems differ from the leaf collar system most University Extension and researchers use. Table 2 in the Corn Growth and Development publication provides a comparison. (Click this to order publication on corn growth and development.)
In brief, the 'horizontal leaf' method used by the hail industry is about one to two stages ahead of the leaf collar system from V2 to V8. That means a V8 plant in the leaf collar system is similar to a V10 plant in the horizontal leaf system. This is important when you use tables like those included in the University of Nebraska publication referenced above.
Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production. He can be contacted by email at firstname.lastname@example.org or (515) 294-6655.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on June 6, 2011. The information contained within may not be the most current and accurate depending on when it is accessed.