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Leaf Scorch on Japanese Mapel

Marginal leaf browning or leaf scorch can be caused by several environmental stresses, which I will discuss briefly. Drought stress, a lack of water in the soil, can cause the plant to sacrifice leaf tissues in order to reduce water use. Excess salts from hard water or from fertilizer can be absorbed by roots and accumulate in the leaf margins, where they eventually become toxic causing marginal leaf burn. Dry air or – even worse – warm, dry air blowing over the plant can cause the leaves to transpire (lose water) faster than the roots can supply replacement water. Again leaf scorch is the result. Moving the plant from shade to high light exposure can have the same result.

If drought shock is the cause, the plant may simply be in forced, early dormancy. This is a physiological survival response. I would not discard the plant yet. Keep the root system moist. You will have to be careful not to overwater since little water use is now occurring. Keep the tree until next spring. It may leaf out again and come out of dormancy. If no leaves appear by May/June, I think you can assume recovery will not occur.

If you suspect that excess salts are the problem, you should repot your maple tree. Unpot the tree, wash most of the old soil off the roots and then repot with new potting soil.