Why are the leaves on my Japanese maple scorched?
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Scorched leaves on a Japanese maple (acer) tree are usually the result of environmental stresses. Japanese maples are the maple trees most commonly affected by this problem. Here’s what causes maple leaf scorch and also how to avoid it.
Acer tree leaf scorch shows up as foliage turning brown, especially around the edges and at the tips. Often the leaves then curl up, shrivel and die. Sometimes branches also die back. Leaf scorch isn’t a problem that causes long-term damage but it is unsightly. Not all scorched leaves completely die and may remain on the tree until it loses all its leaves in the autumn.
What causes Japanese maple scorched leaves?
Scorched leaves on maples in general, and particularly acer trees, are caused by environmental factors, not by disease or fungus. Too much sun, lots of drying wind, frosty nights, drought including underwatering, and being water logged all contribute to this unwanted condition.
Avoiding leaf scorch
Keep trees out of the wind and strong sun
Plant your acer tree in a sheltered location. If you have an unexpected windy period of weather, create a temporary wind screen around the tree. Wind-reduction netting or burlap is good for this.
Most Japanese maple trees prefer partial shade to full sun. If you’re growing your tree in a container, feel free to move it around to keep it in the shade during the sunniest hours of the day.
Keep the soil well drained
Acer trees need a well-drained soil to thrive. Add organic compost to ensure that the soil doesn’t become water-logged. On the other hand, the water should not run away quickly either. Strike a good balance so that the tree has all the moisture that it needs.
If you’re growing your maple in a container, pay particular attention to its moisture needs and water regularly. Trees grown in pots dry out quickly.
Protect the soil
Retain the moisture in the soil by applying a layer of mulch around the base of the tree. But leave a gap of around 30cm between the tree and the mulch. You don’t want decomposing matter to touch the tree trunk or lower branches as that can cause disease and illness for the tree.
Also, apply mulch to the top of the soil if you’re growing the Japanese maple in a container. Here you may want to use inorganic matter such as gravel as you don’t have much room to keep organic mulch away from the tree.
Avoid frost conditions
Of course, you can’t avoid frosty weather. But you can look after your tree when cold nights are in the weather forecast. Move your container tree to a sheltered location, perhaps in the corner of two outside walls where it’s warmer. For trees planted in the ground, consider covering them in several layers of horticultural fleece for the night. Morning sun followed by a frosty night-time is a difficult combination for the trees to endure.
You can learn more about how to protect acers in winter here
I also have a guide which covers other acer problems here
Finally, learn more about growing acer trees in pots here and how to plant an acer in the ground here