Recent storms that have rolled through the state have unfortunately brought high winds with them. I’ve gotten several calls about corn that has snapped and corn that has been blown over. Green snapped corn and corn that has blown over are two different problems, although most of the time you will have both problems in the same field.
Greensnap is when the corn stalk snaps at a node. This can occur anytime from once the growing point is above the ground (~V6) to after tassel, but most often occurs when plants have been rapidly growing and the stalks are brittle and have not “hardened off” yet. High nitrogen rates and good growing conditions (both of which we have had) increase greensnap problems. Some hybrids are more likely to greensnap than others. Although with 80MPH winds reported in some areas, most hybrids would snap under those types of winds. Fields planted east and west typically has more damage than those fields planted north and south (assuming wind was from the north). Figure 1. below shows what typical greensnap injury looks like. Some fields in NE Arkansas in isolated areas have been reported to have 75% or more greensnap damage.
Unfortunately yield loss associated with greensnap is nearly directly proportional to percentage of plants that have snapped since most plants affected appear to be within a week or two of tassel. Plants at this stage have little ability to compensate since the maximum number of kernels has already been set. There still may be a small amount of compensating that a plant can do, but it is not nearly as great as if the damage had occurred earlier in the season.
For fields that have sustained heavy greensnap damage there is no good solution. Having insurance that covers greensnap damage is the best case scenario. Fields not covered by insurance become more difficult to deal with since replanting corn or grain sorghum this late in the season is not going to provide optimum yields. In irrigated planting date studies I have conducted at Marianna, AR in the past few years, Mid-June planted corn and grain sorghum averaged about 65-70% of maximum yield, which in my plots translates into about 150 bu/a for corn and 85 bu/a for grain sorghum. These yields would generally be considered high for that late of planting date and are from small plots. Corn herbicides applied may not allow for soybean planting. If replanting of any sort is done, corn stalk shredding would likely have to be done to be able to plant another crop. The best option in many fields with moderate greensnap would be to keep the corn crop because a reduced yield due to greensnap may be as good as or better than replanted corn or a late grain sorghum crop since nearly all the expenses are already into the corn crop.
I’m also getting several reports that corn plants are “leaning” or have blown over, but do not have any greensnap. This problem looks bad, but the plants can somewhat straighten up and most likely will not have a large impact on yield. In these situations, the roots most likely gave way (especially if the ground was wet). Figure 2. below are some pictures from past years where plants that blew over straightened up and yielded well. There may be some yield loss associated with this from plants shading other plants or from silks being covered up by leaves and not getting pollinated. The smaller the plants are, the better they will straighten up. Plants that I have followed in past years that “goose necked” back up still yielded well, but in general harvest speed was slowed down a little.