Red Japanese Maple, 25 feet tall, about 30 years old which has been beautiful and healthy until a short while ago. The leaves have suddenly acquired a whitish edge and a closeup photo of the leaf reverse shows a blemish aa well as a swelling at the base of a branch. Two other Japanese maples in the neighbourhood show peculiar symptoms where their red leaves are turning green.
Thank you for your enquiry about damaged leaves on your lovely Red Japanese Maple. We believe that your tree has succumbed to the heat, drought, and drying winds of this past summer resulting in leaf scorch, which is a minor problem in an otherwise healthy-looking specimen. The images in the two university websites noted below, show photos of similar scorch damage as well as a comparison with diseased leaves which display different symptoms. The neighbour’s artificial turf severely limiting water penetration would exacerbate the problem. The section of green leaves would reflect the shade thrown by the tall house next door because red coloration requires greater sunlight.
In addition to watering the tree during droughty periods, applying about 2 inches (5 cm) of well rotted compost or well rotted manure over the root area, while keeping it an inch or so away from the trunk, will help to retain moisture to prevent further scorching as well as providing nutrients.
I hope that you enjoy this beautiful tree for another 30 years.