Deficiency shows up in younger leaves as stunting or abnormally small leaves. The area between the veins turns yellow and bronze colored spots form around the margins of the upper leaves. Leaf tissue between veins turns a creamish yellow while area along the veins remains green. Plants have stunted leaves that are curved upwards, looks like leaf roll virus. In general, leaves are smaller, internodes shorter and stems are more rigid.
Zinc sulfate can also be mixed with lime or soda ash to form a longer lasting film on leaves.
Zinc oxide can also be used which puts fewer residues on the foliage. Heavy residues can encourage scale insects and mites. Leafhopper damage may be mistaken for zinc deficiency. The primary difference is that the leafhopper punctures the midrib of a leaf and causes a yellow discoloration in the form of a v. Plants suffering from a virus or fungus disease can appear to have a zinc deficiency due to a reduced root system. Increasing soil pH decreases zinc availability and uptake by plants.