See:
Maple (Acer spp.) - Leaf Scorch
Cause These are shade loving plants that do not tolerate full sun even for part of the day. Drought or heat stress can also cause leaf scorch. In general, there is not enough water reaching the leaf margin to keep up with transpiration. Any interruption of the vascular system can produce these symptoms. Over-fertilization, salt damage, can result in similar symptoms where salt has been translocated to the leaf margins. Poorly installed plants with lack of root establishment can also result in the same symptoms and may be referred to as transplant shock.
Symptoms Leaves get a washed out chlorotic look or have marginal or tip necrosis when in full sun. Leaf margins and areas between veins turn brown to black. Shoot dieback may follow. Sun or heat related stress will occur primarily on the south side of plants. Bushes may decline after repeated annual exposure to sun.
Cultural control Prevention is the key as there is no remedial action that can be taken once leaves are scorched by the sun, but effects are not fatal and new leaves can eventually cover damaged ones.
- Plant in shady areas and/or protect from full sun exposure.
- When irrigating, wet the entire root zone infrequently during the summer. Avoid over-watering.
- Provide good drainage and avoid soil compaction.
- To avoid reflected heat, do not plant close to buildings or paved surfaces, and avoid rock and black plastic mulches.
- Avoid root and trunk injury.
- Do not over-fertilize.
Chemical control Use before hot summer weather. Always follow pesticide label directions. Anti-transpirants or anti-desiccants are not recommended since they have not been shown to be effective at preventing heat or cold-induced desiccation of plants beyond their normal adaptations.
- Surround CF at 6.25 to 37.5 lb/A plus a surfactant. A dry white film will result on all treated plant parts. 4-hr reentry. O
Reference Chalker-Scott, L. 2010. The myth of antitranspirants, pp. 183-189. In The Informed Gardener Blooms Again, University of Washington Press, Seattle, WA.