Question
Hi Jim,

I just noticed my maple tree has many leafs with "spikes" coming off them.  Some leafs have just a few popping out and some have 100's. The leaves that have it look like little spikes coming off?

Any ideas?

Thanks,

Chris
Vermont

Answer
This is a gall mite called Maple spindle gall.
Maple Spindle Gall Mites (Vasates aceris-crumena Riley) cause spindle galls to form on the upper surface of maple leaves. During certain seasons the galls are common on ornamental and forest hard maples.
Spindle galls are about 1/5 inch long and similar to a pencil lead in mid-diameter, tapering to both ends. Since the erect galls are conspicuous and characteristic, identification is easy. The life history and habits of this mite are similar to those of the bladder gall mite. The mites overwinter under the overlapping scales of bark in the vicinity of scars and the ends of broken branches. Spindle-galls are extremely variable in abundance.

Although the galls can be unsightly in ornamental trees, you rarely need to treat the condition except for aesthetic purposes, or to protect recently transplanted young trees. The galls do little actual harm. Efforts are best spent on good horticultural practices, such as watering and fertilizing, as needed, rather than spraying.