Hello Dan. From the photo I don’t see any signs of a disease. I do see symptoms of left scorch, with the leaves turning brown from the edges inward.

Most types of Japanese maples do not like direct sunlight. They prefer more dapple light. On the west side of your house they are exposed to direct afternoon sun and hot conditions, assuming there are no shade trees overhead.

While you can’t do anything about their location, you can help offset the effects of where they’re located. Left scorch is a result of the leaves loosing water faster than it can be replaced. To offset this make sure the trees are gettin adequate water. Less frequent deep watering is better than frequent shallow watering. To help conserve soil moisture apply a 2 to 3 inch layer of mulch under the trees out to the edge of the limbs. And avoid volcano mulching. Don’t put mulch up against the trunks of the trees.

Here is a factsheet with more information on Japanese maple and their care.

Thank you for your question.

New Hampshire