Japanese maple leaves can be spotted and the veins within the leaves can be blackened. Tips For Winterizing Japanese Maple Trees As winter approaches your maples are losing their leaves, going dormant and preparing for winter. If bright beams donât let up for most of the day, the tree is likely suffering from environmental leaf scorch. These pests drill into the bark and tunnel along the trunk and branches. Treatment: Most maples will show burn their first few years as they acclimate to our climate. It is identified by its leaf color – a deep red that shows up in the fall, making it really attractive as a decorative tree in this season. In this case, your tree probably just isn’t getting enough water. It could just be a temporary problem due to heat and sun stress from a long and hot summer. As is obvious from the name, the Japanese maple has its origins in Japan. Japanese maples might be small, but they dry out pretty easily without a steady dose of hydration. Japanese maples are pretty tough trees, but not immune to pest problems. They’re rarely found on Japanese maple, but some readers state they’ve seen this pest. Outer leaves mainly show burn while those underneath are fine. Hereâs how to remedy that. Cause: Excessive sun, irregular watering, afternoon water on leaves. The answers also ranged from 'fungal infections' to 'too little water,' which is a pretty big range. A hot summer can leave even established specimens that are too exposed to sun with brown leaves, especially if other debilitating factors are present.