This could be anthracnose or rust, a problem this year with the wet spring weather. Keep damaged foliage cleaned up and discarded, water from below, and redirect lawn sprinklers so leaves stay dry. Applying chlorothalonil or copper- based fungicides are effective at protecting clean buds and foliage from both rust and anthracnose. Here are descriptions of leaf spot diseases-
The “windowing” at the edge looks like insect damage. To accurately diagnose which fungal issue it is, leaves need a look under magnification. You can submit samples to
for exact diagnosis. Thank you for using our service.