Anthracnose (Discula, Kabatiella apocrypta) is a disease caused by fungus spores. It is not to be confused with Tar Spots which look dramatic, which is also a fungus disease. Typical symptoms on maple trees are brown areas on the leafs, irregular, light to dark brown spots form along or between veins extending to the leaf margin. The disease might break out after changing to more humid and less ventilated climates. The leaf deformation is very different from draught stress. Also, the infection might come along with other pests. The disease might be fatal to the tree. For control the Royal Horticultural Society recommends application of copper based fungicides which in my case did not show significant effect. Also fungicides containing mancozeb are recommended (for example Manzate 200 or Dithane M-45). In Beijing it is not easy to buy such chemicals, as the shopkeepers and farmers have usually no idea what they are selling and how dilution and application should be handled. Given that some of these chemicals are very poisonous, I do not even want to think about that kind of vegetables I am eating here on a daily basis. A pack copy of what I am usig to treat my maple tree is attached for reference. Also treating the soil surface seems reasonable, as well as removing infected leaves.