08 Jun How to assess corn damage
Recent storms have caused a variety of damage to Mississippi’s corn crop and left growers with management questions.
“Likely the most prevalent problem since last weekend has been hail, although ‘greensnap’ (a term describing corn stalks broken by high winds) and flash flooding have also occurred,” writes Erick Larson, Extension grains specialist with Mississippi State University, in a newsletter released in early June. “After the early vegetative stages, hail primarily damages corn plants by destroying foliage and thus reducing the plants’ photosynthetic capability.”
To read the full newsletter, go http://msucares.com/newsletters/grain/2010/0604.pdf.
Larson characterizes the different damage, how to calculate defoliation levels and when a corn crop is most vulnerable.
Also discussed: when a nitrogen application is warranted, and how to apply it, following a heavy rain. “Corn growers in northern counties where frequent rains have prevented intended nitrogen application may need to aerially apply nitrogen, because crop height and wet soils may prohibit utilization of ground equipment,” writes Larson. “However, we do not suggest applying nitrogen fertilizer when soils are completely saturated, flooded or ponded, because anaerobic conditions stunt crop growth/response and promote nitrogen loss. Two sources of granular nitrogen fertilizer are generally most feasible for mid-season topdress application on corn – ammonium nitrate and urea.”