Richard Taylor, Extension Agronomist; rtaylor@udel.edu
During the past two growing season, I’ve tried a number of remedies for a common early season problem on field corn. It seems that more and more corn has been showing distinctive interveinal chlorosis (yellowing between the veins) on the upper leaves. A number of theories have been bantered about as to what these symptoms represent and if they are even meaningful from a final yield point of view. Farmers who have kept track of the problem areas and who have yield monitors have not reported that lower yields are necessarily associated with these symptoms. It may be that small yield effects do occur but so far the yield effects mostly have been very subtle. Up to now, I’ve tried foliar applications of manganese, zinc, copper, iron, boron, magnesium, and sulfur (usually as a component with one of the previous cations). None of these foliar-applied nutrients have lessened the symptoms. The corn does tend to grow out of the symptom when it reaches the rapid growth phase around side-dress time.
I will continue to look at this situation and try some soil-applications since some work Dr. Greg Binford did last year seemed to indicate that soil applied sulfate may help. Another possibility since we’ve had two very unusual springs is that on early-planted corn that received substantial amounts of cold rain, root system restrictions from some production factor may be limiting nutrient uptake leading to smaller, yellowed (interveinal yellowing) corn. For the most part, warm temperatures and corn reaching the rapid growth phase of development seems to be initiating the recovery of the crop.
If you’ve seen this type of problem in some of your corn fields, please take time to pass along to me or your Extension ag agent as much information on your production practices and weather for these areas as possible so we can try to understand more about this problem. If you have a yield monitor on your combine and can yield check problem areas versus nearby good areas, we would appreciate learning if your yields have been affected.