Question
My maples has just been planted. Over the last 5 weeks it have formed brown spots on the leaf edge and leaf interior. It is in a very windy place but gets plenty of water and is in the shade 90% of the day.What is going on? Thank you.
Julie

Answer
These are leaf spot caused by a fungus. I am going to guess it is Phyllostict leaf spot. A leaf spot that infects late in the growing season causes very little damage except maybe the leaves will fall earlier than normal. If you want to control the fungus the leaf surface would need to be sprayed with a fungicide in the spring. A large tree would be difficult to spray and in my opinion not worth the effort since the damage to the health of the tree is slight.
Phyllosticta Leaf Spot of Maple. Pathogen: Phyllosticta minima

Like many fungal leaf spots, this disease affects a number of maple species, most prominently Amur, Japanese, red and silver maple. The disease causes little damage because the infection is localized. Spots are roughly circular and develop into tannish spots with purple to red borders. Later in the season the spots often contain black fruiting bodies of the fungus arranged in rings inside the lesion. Although this disease is quite noticeable in the landscape, especially on silver and red maples, and causes concern among homeowners, damage is minimal and fungicides are rarely necessary. If fungicides are required use a labeled product containing mancozeb or chlorothalonil. Fungicide will have to be sprayed on the new leaves and will wash off with rains and will need to be applied every 14-21 days if it rains so since the spots do not damage the tree I would not worry about them.