Of the agronomic crops, corn is especially sensitive to zinc deficiency. The major symptom of zinc deficiency in corn is broad white stripes in the leaves at or near the growing point in the early growth stages of the plant. It has been referred to as "white bud" disease because of the characteristic whitish area on one or both sides of the midrib near the base of new leaves. It can be seen as a new leaf unfolds from the whorl. Growth is stunted resulting in shorter than normal internodes. The pith of the stalk may become darkened at the base of the stalk (below ground level) and at the first leaf node. Sometimes the lower leaves become purple.
Frye, W. W.; Miller, H. F.; Murdock, Lloyd W.; and Peaslee, D. E., "Zinc Fertilization of Corn in Kentucky" (1978). Agronomy Notes. 110.