By examining the leaves carefully, you will know what should be applied such as zinc sulfate, ferrous sulfate and magnesium sulfate. Because you can see the changes in color, shape and size of the deformed and discolored leaves. And each symptom leads to a different diagnosis.
Leaves in General
1 Examine the plant carefully, from top to bottom. Note if the symptoms extend over the entire plant or only on the lower leaves.
2 Look closely at the leaf colors. If the plant is suffering from a nitrogen deficiency, all the leaves are light green, with the lower leaves turning yellow and drying to brown. If the leaves are dark green or reddish-purple and the lower leaves are drying to dark green, the plant is lacking in phosphorus.
3 Examine the older lower leaves. If the edges are yellow but still green in the center, the plant needs magnesium. Thus, we can spray magnesium sulfate solutions or apply magnesium sulfate to correct this condition.
1 Look for yellowing leaves. If the new leaves are yellow and the yellowing is spreading across the plant, the plant is lacking in sulfur.
2 Examine the area between the leaf veins for yellowing. If the plant needs zinc, the leaves are also crinkled and distorted and the stems are shorter than normal. Generally, this condition can be corrected by apply zinc sulfate.
3 If the stems are normal but the leaves have dead spots developing, the plant needs manganese. If the leaves are normal except for yellowing around the veins, the plant is lacking in ferrous. A common measure to remedy this symptom is to spay ferrous sulfate solutions.