Hi there: our northfacing house has a large maple (I believe it is a silver maple) that almost overnight starting developing rot/black and brownish curling after the tree’s leaves started to mature (about a week or so ago). We have been raking up diseased leaves that are dropping. The tree is taller than our 3 story house, and it appears that the leaves up high are also affected but not nearly as much as the lower branches and sucker branches. We just moved in over the winter but it is our sense this tree has not been pruned or maintained in a while. We did some googling and we think it could be anthracnose, but aren’t sure. Hoping you can help us identify it and give us a prognosis: is this fatal? Is there treatment for such a mature tree? Or will the tree be fine next year? Should cut off the lower branches? One final note is that there is a maple tree of the same species on our street half a block or so down that is suffering from the same condition. I have more photos but could only attach one so I chose a close up of a fallen leaf.
Thank you for your recent query concerning your maple tree. Looking at the photo you sent that your silver maple may be suffering from anthracnose, a fungus which flourishes in cool, wet weather such as we have experienced this spring. (I have seen evidence of infected trees during my walks through a local city park.)
You are right to be diligent in cleaning up infected leaves. This is especially important in the fall to prevent overwintering of spores and re-infection of the tree next spring.
As you have noticed, young leaves and shoots are affected more so than older leaves probably because of poorer air circulation.
Several sources I checked claim that the disease is rarely fatal but certainly a healthier tree will recover more quickly. Pruning of the lower branches is recommended to increase light penetration and improve air circulation. Some sources suggest pruning throughout the canopy as well.
Since you are not sure of the tree’s maintenance history and since it has exceeded the height of your 3-storey home it is prudent to seek the services of a certified arborist for a positive identification and maintenance plan. Older trees should be assessed for health, structure and balance. Landscape Ontario lists certified arborists
Here are some additional sources you may wish to consult:
Good luck with your tree!