Please help me in identifying the disease on this tree.
There are black patches on the leaves.
Thank you for your recent query concerning your tree. It is difficult from your photo to determine the kind of tree you and disease you have. It is possible it is suffering from anthracnose, a disease caused by several species of fungi.
Anthracnose flourishes in cool, wet weather such as we have experienced this spring. Frequent rain and wind aid in the dispersal of infectious spores. (I have seen evidence of infected trees during my walks through a local city park.) Several species of shade trees found in Ontario (maple, oak, walnut, sycamore) are commonly infected.
It’s important to be diligent in cleaning up and disposing of infected leaves. This is especially crucial in the fall to prevent overwintering of spores and re-infection of the tree next spring.
Young leaves and shoots are affected more so than older leaves probably because of poorer air circulation.
The good news is that 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. However, depending on the height of the tree and its overall health you may wish to seek the services of a certified arborist for a positive identification and maintenance plan. You could check with Landscape Ontario for a recommendation:
Here are some additional sources you may wish to consult. These links may help with verifying that this is the same as what you are seeing on your tree.
Good luck with your tree!