Impossible to tell exactly what's going on by remote but I'd suspect some sort of water issue. What's your summer been like and how did this little tree get watered?

dead is dead.. sip out the dead branches ... prune properly ... ask in the tree forum if you dont get an answer here ... i dont know how active this forum is ... the key is to leave branch stubs ... see link

i dont really care about leaves turning weird colors in fall ... heck.. 1/3 of the trees in SE MI are showing signs of coloring ... not much to do.. to save leaves that will fall off inside a few weeks ... not even worry ...

i suspect a large window to the left ... perhaps it was spray clened.. or someone scraped by the plant ... in other words superfiscial chem damage ...

all that said.. it was a horrible winter last year... i had a lot of small branch death on my few JMs ... seems coincidental that all the damage MIGHT be on the part that wasnt snow covered ... eh?? .. any way to support that theory ???

ken

Here is a link that might be useful: link

Don't prune anything yet! Japanese maples often lose foliage during the summer months as a result of drought stress and come back just fine in the following season. If you see no sign of life on those branches next year when the tree should be leafing out, then you can remove any dead wood.

Ands even if Ken is correct about some chemical damage - JM's can be very sensitive with regards to substances on their foliage - that does not necessarily mean the affected portions are dead.

In short, it's just soon to be removing branches willy-nilly without knowing more precisely what's going on. Let us know about your watering routine......

at the very tip of a grey branch.. just try to snap it...

if its dead.. and dry ... grey ... it will snap right of ...

if its just leafless ... it will have integrity and bend.. not snap ...

if its dead.. its dead .. there is no cambian layer under the grey bark ..

if dead.. with good pruners.. just keep cutting back.. one inch at a time... until you see the green cambian layer ... then you know you are in live wood ..

at that point ... you then look to see... where the last ... PROPER ... cut should be made ...

or you wait until spring.. and do the same.. on any parts that dont leaf out like the rest of the plant .... there really isnt any hurry on tree pruning ... most of the time .... especially on a short plant like yours ....

ken

Here is a link that might be useful: seeing the cambian thru pruning is an offshoot of the scratch test ....

Wow, thanks for the help guys. As to the watering, it's been a wetter summer than most in Waterloo Ontario so no extra watering done really. The ground in this garden is well drained so no waterlogging that I am aware of. I trimmed off the white top branches today which were dry and brittle. Found a cluster of what appear to be insect eggs or fungus at one of the "armpits" on dry wood. They were bright orange in colour, adhered to the wood and about the size of small cookie crumbs. May not be a smoking gun though. All the dead material is trimmed back to the live wood now so I'll monitor to see if the die back is halted. Thanks