What causes white leaves on tomato plants?

- Magnesium deficiency - In this case, the leaves might be lighter in colour, with some yellowing or wilting.

- Iron deficiency - This would cause the leaves to turn pale yellow or white, with darker veins.

Chemical Damage:

Sometimes certain chemical sprays can damage the leaves if applied incorrectly, causing the leaves to turn white or light-coloured.

Disease:

- Verticillium Wilt - This is a soil-borne disease which causes the leaves to wilt and turn yellow or white.

- Alternaria Blight - This fungal disease causes brown spots on leaves which can eventually turn white and dry out.

- White Flies - These small insects can cause leaves to turn white or yellow as a result of feeding.

- White Rust - This fungus causes white powdery spots to appear on leaves.