Cedar-apple rust
With leaves still absent from many trees, it is not hard to see evidence of galls caused by insects, such as the oak apple gall, or by fungi, such as the knobby black protrusions on black cherry trees referred to as black knot. A gall is an abnormal outgrowth of plant tissue, which can be caused by all sorts of parasites, from fungi and bacteria to insects and mites. Another fairly common gall in this area is one called cedar-apple…