Integrated Crop Management is published by the Department of Entomology , Iowa State University , Ames, Iowa. This deficiency in corn is frequently observed after a lack of rainfall in June. Soil compaction aggravates the problem. Symptoms of K deficiency that are induced by dry weather may be somewhat different from classic symptoms of K deficiency. Classic K deficiency symptoms appear on the lowest leaves of the plant, first as yellowing at leaf tips, then progressing down leaf margins.
Leaf margins turn brown as they die, and symptoms move progressively up the plant on the leaves.
The entire leaf eventually turns yellow, which produces a yellowish sheen to the plant except for newly-emerged leaves that are a normal green color. If the plant is unable to take up K from dry soil, sufficient rain will allow the plant to resume normal growth, but existing deficiency symptoms will not disappear. If the problem is due to actual lack of K in the soil, the symptoms may continue to increase and result in a severe yield reduction. There is no corrective treatment for this year's crop. If you see the symptoms described, sample and test the soil for K. Sample at different depths if you suspect that surface stratification of K is caus-ing the problem.