Excess of sulfur may cause premature dropping of leaves. Iron Deficiency Toxicity Interveinal yellowing in young leaves with fine veins still green. Young leaves completely yellow or white with some necrotic spots. Possible bronzing of leaves. Manganese Deficiency Toxicity Interveinal yellowing or mottling of young leaves.
Older leaves have brown spots surrounded by a chlorotic circle or zone.
Excess zinc may cause iron deficiency. Boron Deficiency Toxicity Death of growing point and deformation of leaves with area of discoloration. Leaf tips become yellow followed by necrosis. Leaves show scorched tips and margins. Essential Plant Nutrients, University of Guam.