Oak, maple, and bittersweet seedlings are coming on strong with the onset of the hot weather. Usually less than ten inches tall at this time of year, they seem to have the strength of full-grown trees when one attempts to pull them out!
I mentioned a tip last year for their removal that works so well that I wanted to mention it again. The tool that works best for their removal is a simple pair of pliers. Grasp the plant at or just below soil level and give a firm pull and twist of the wrist. In most instances, you will end up removing the seedling root and all!