Japanese maple prone to brown spots
Brown tips on the leaves of Japanese maples is a common occurrence caused when the plant becomes dried out due to excessive sun exposure, wind or fertilizer. As long as the brown stays within the leaf tips, don’t worry about it this year. Most likely, the browning is a reaction to the planting.
Once a leaf has a brown tip, it will stay that way. If a single dry spell caused a reaction from the plant, then it will remain the same all summer. However, if the leaf becomes more dried out, the plant will continue to have problems.
To get to the root of the problem, investigate some common causes for the symptoms.
If only one branch is affected, then try to figure out what occurs only on that one side. Is that the side the wind or sun comes from? Maybe that one branch was damaged during planting or shipping and it is slow in showing up.
When a branch breaks, make a clean wound by using a pruning tool or saw to cut off the stub. Don’t paint it with anything and the tree will create scar tissue to grow across the wound to heal itself.