Our ~30 year Japanese Maple showed brown leaves in spots all of a sudden (see picture). Most of the tree looks great, just these patches of dead leaves. While the dead leaves are in two seemingly different spots, we traced it back to the same main branch off the trunk. Everything on that branch is dead. There's no signs of being broken or bark stripped off. I can find no sign of insects (e.g. bag worms or such) except for a few minor spider webs elsewhere on the tree. No other limbs seem to have any issues. I can certainly cut off this branch (if I should, is it OK to do that since it's dead anyway or wait until another time with less stress given the heat and drought?). But my concern is more is there something wrong that will eventually impact the rest of this tree. I should also note that there's a Japanese maple of the same variety 15 feet away (we bought and planted them at the same time). It looks fine. So in summary, should I cut this off now or wait? Is there, and if so what, an issue that will spread to the rest of the tree? What could it be? What should I look for?