by John S. Kruse, Ph.D.
We have recently received reports of corn plants snapped off or crimped and laid over. The injury is most often associated with violent storms producing winds, but not always. “Brittle snap” or “Green snap” is much more widespread in the Midwest and High Plains where high winds can cause substantial damage, but occurs in Louisiana from time to time, particularly during periods of active weather. The damage usually occurs below the point on the stalk where the ear sets, is very visible, and generally results in total yield loss for that plant once the stalk has broken or severely crimped and fallen over. There are several factors that can contribute to brittle snap, including wind speed and direction, growing conditions, and hybrid type.
High wind speed, particularly when it hits perpendicular to the corn rows, is the main factor causing brittle snap. Injury may be more likely to occur during wind downbursts from a storm cloud, creating areas or pockets of damage in a field. If the winds hit during cooler periods of the day when transpiration is reduced and the plant is more turgid, the injury may be more widespread.
Growing conditions can be a factor as well. Warm weather, adequate soil moisture, and high soil nitrogen levels allow for rapid vertical stalk growth from roughly V5 to V18. Rapid cell elongation is occurring – thinning the cell walls – leaving the stalk vulnerable to snap. Inadequate potassium in relation to the amount of nitrogen available may exacerbate thin cell wall issues.
Corn seed producers recognize there are differences between hybrids as to their susceptibility to brittle snap. Some companies take the time to rate and report brittle stalk ratings, and it is worth taking these ratings into account when making seed buying decisions. Thin, rapidly growing stalks, high ear placement, and inherently thin cell wall structure in some hybrids make them more vulnerable to brittle snap than others. It may be that a few hybrids are susceptible enough that equipment (such as a boom) running through the field could knock over the plants, so producers should be aware if this is occurring and consider a different hybrid in the future.