Early season stresses can trigger any of a number of plant responses, including striped leaves. For the most part, this striping is probably genetic. There have been suggestions, however, that the striping may result from very rapid growth during a warm period that follows slower growth during a cooler period. The condition is temporary and to my knowledge, does not affect subsequent plant growth and development or yield. Although the symptoms mimic certain nutrient deficiencies, such deficiencies are rare to nonexistent in Iowa and generally are related to soil pH.