![]() ![]() Thus, you can usually stage a damaged crop by the leaf collar method and then add one or two more leaves to the count in order to use the defoliation chart. See my Corny News article for more details. Identifying true “droopy” leaves on shredded, hail-damaged corn plants can be quite difficult, whereas leaf collars are often still identifiable. That chart is reproduced in the Purdue Extension publication ID-179, Corn & Soybean Field Guide. The usefulness in understanding the differences between these two leaf staging methods lies in the fact that the yield loss chart used by hail insurance adjusters to estimate yield loss due to defoliation is based on the “droopy” leaf method. After corn reaches 18 to 24 inches in height, the leaf collar method will typically result in a leaf stage value that is numerically two less than the “droopy” leaf method. For example, the images to the left show the same corn plant that could be staged either as V3 by the leaf collar method or as a 4-leaf plant by the "droopy" leaf method. Up to the 5- or 6-leaf collar stage, the leaf collar method will typically result in a leaf stage value that is numerically one less than the “droopy” leaf method. Both methods assign a leaf stage to a field on the basis of the leaf stage common to the majority of the plants in the field. In knee-high corn or older, the tip of this “indicator” leaf typically also “droops” or hangs down, thus I refer to this as the “droopy” leaf method. Leaf counting then differs, though, by ending not with the uppermost leaf with a visible collar, but at that leaf that is at least 40 to 50 percent exposed from the whorl. Like the leaf collar method, this method of leaf staging begins with the short first leaf. Crop insurance adjusters, when assessing damage to a corn crop from weather events such as hailstorms, use this leaf staging method. Same plant, but staged as 4-leaf according to the "droopy" method. Young corn plant staged as V3 according to the collar method. For example, if half or more of the plants you rate are at the V5 stage of development, then the entire field is assigned a V5 rating. By definition, the specific leaf stage for an entire field is defined by that value that represents the majority of the plants in the field ( Abendroth et al., 2011). TIP: Recognize that not all plants in a given field will be at the same leaf stage at the same time due to normal variability among plants for emergence or subsequent exposure to stress. The leaf collar method is generally the most widely used method by university and industry agronomists in the U.S. Leaf stages are usually described as “V” stages, e.g., V2 = two leaves with visible leaf collars. The exception to this statement may be that leaves with barely visible leaf collars can be counted when you are staging plants early in the day, recognizing that the leaf collar may become completely visible by the end of the day. Leaves within the whorl, not yet fully expanded and with no visible leaf collar are not included in this leaf staging method. The leaf collar is the light-colored collar-like “band” located at the base of an exposed leaf blade, near the spot where the leaf blade comes in contact with the stem of the plant. ![]() This method determines leaf stage in corn by counting the number of leaves on a plant with visible leaf collars, beginning with the lowermost, short, rounded-tip true leaf and ending with the uppermost leaf with a visible leaf collar ( Abendroth et al., 2011). There are two basic methods for leaf staging corn that are used by agronomists and hail loss adjusters in the field today. Counting the number of leaves would seem to be a simple way to document corn development, but folks still tend to become confused over this simple strategy. Some of you may have spent more time in your youth standing in the corner, but that is between you and your parents.īecause it is difficult to transport corn plants from the field to that doorframe to measure their growth, agronomists developed other means to measure the phenology or development of corn. Any of us remember standing against the doorframe in our early years while our parents marked our height with a pencil to measure how much we had grown.
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