A few other things that can cause "burned" leaves - too much fertilizer and too much wind. Either can burn leaves of an otherwise healthy tree.

K4

It sounds like you've been growing it in Oklahoma! Hot winds is the answer I think. My ornamental trees and just about everything else get that look around here in late summer or even early summer depending on how hot it is. A couple years ago it was so hot that all the leaves were shed before Fall. Try to keep it cooler and with less wind in the future.

I've got a 'Bloodgood'. Its leaves fry during the summer and becomes completely naked. I'm hoping it will better handle sun when it becomes more mature. I should probably stick with the species Japanese Maple since I have little shade, but Bloodgood sure looks good in the spring.

Randy

If the shade the Bloodgood is in comes from a much larger tree, it's very likely the big tree is out-competing the Bloodgood for water, even after six years. This would be especially true if the soil in which the Bloodgood was planted was amended; this would have attracted the roots of the larger tree.The much smaller transplanted root mass of the Bloodgood can compete in early spring, but when the larger tree is fully leafed out, it will suffer. Even record rainfall will not necessarily help, although it's obviously much better than drought.
If the shade is not from another tree, then wind, excess fertilizer, lack of water holding organic material in the soil,and/or too little mulch are likely culprits.

Thanks folks - it's not very windy in my backyard - small with a high fence gives it a nice calm space. Shade is provided by two trees - each about 30 metres high, planted six to ten metres away so perhaps their roots are sucking up moisture. I never fertilize my garden - just keep throwing compost and mulch all over, and the little hill the tree is growing on is underplanted with Hosta so there's no bare soil at all.

Guess I'll try using the hose more often this summer.