Cornus kousa browning & purple tinged down mid vein to tip
My (until last week) healthy vigorous cornus kousa suddenly has a number of leaves which are brown from the mid vein down to the tip in almost a triangular shape. At the tip they have dried up completely. There is a purple edge to some of these which is more visible on the back of the leaves. Google suggested athracnose but I can’t see any fungal or insect damage and am hoping that this is just due to a very wet June with strong winds over the last week. The plant is about 8 years old, 8 feet tall and is just finishing flowering (best it’s ever flowered). I’d really appreciate ideas as to what it could be and what action I could take please.