Japanese Maple Leaves Brown and Curling


I checked the “find it here” about this issue and got either my tree is suffering from sun scorch or a fungus but I do not know how to tell which one it is so I am hoping you can help me. The tree is approximately 10 years old, faces southwest and is in full sun.


There are several possibilities for the leaf curl you describe on your Japanese Maple, see below.

  1. Water shortage – dry soil conditions leading to uniform wilting and dieback of younger leaves.
  2. Wind burn – typically effecting the leaves on the west side of the tree.
  3. Sun Burn – typically effecting the outer top leaves.
  4. Aphid infestation – sucking insects visible on the undersides of leaves, they produce a sticky honeydew which ants find attractive.
  5. Viral infection – transmitted by sucking insects.
  6. Bacterial leaf scorch – transmitted by sucking insects.
  7. Fungal infection – transmitted by wind, animals, tools or water splash from contaminated soil.

As your tree is 10 years old, I’m assuming it is now quite large so the only real remedy for numbers 1-3 is a consistent regimen of watering and fertilization.  Numbers 3, 4 & 5 are caused by a pest infestation so a close inspection of your tree is needed.  If you find aphids or other sucking insects, you can try to deal with it yourself with a good blast of water from the hose or an insecticidal soap spray.  A fungal infection is usually a soil born pathogen which is spread by one or more methods and if in doubt about this diagnosis, a certified arborist or tree care professional could help.

All this being said, there are some basic care tips that you can implement that will help.  Watering deeply and feeding your tree is vital especially as it is growing in full sun.  Mulching around the base of the tree will also help retain soil moisture but make sure the mulch is kept 3-6 inches away from the tree trunk.  In the fall, all leaf debris should be raked, cleaned up and disposed of prudently (do not home compost this material).  Lastly, all tools (especially cutting tools) used in your garden should be sterilized when moving from plant to plant – this can be done easily using a bleach & water solution.

Hope this helps.

August 1, 2021