I have a Bloodgood Japanese Maple about 30 years old. It is green now, as it is under the shade of a larger maple tree. One branch,

Question

however, in the middle of the tree has bright red leaves. What would cause this?

Answer 1

Usually, this is caused by the grafted rootstock sending up a shoot of its own. This is not good to let get mature, as it is usually more vigorous than its grafted top. Leaving this can steal nutrients away from your grafted top. You can safely prune this away.

This article will help you with the care of Japanese maple trees:https://www.gardeningknowhow.com/ornamental/trees/japanese-maple/japanese-maple-care.htm