I'm sorry - the photos are too dark and indistinct to be helpful.

Japanese maples will often experience some winter dieback. Typically, it is restricted to smaller stems and branches and on larger JM's like yours, generally just ignored unless easy to reach and remove.

Larger branch die off could be a sign of something more serious. Verticillium wilt is a soil borne pathogen that is omnipresent and can infect, damage and kill a very wide range of plants. Japanese maples are very prone to this disease. It is also very opportunistic, lying dormant in the soil for decades until activated by some sort of chemical signal. Generally the signal results from some sort of injury or mechanical damage (especially with the roots) but stress can also be a strong factor - drainage issues, drought, temperature extremes can all be contributing factors.

There is no cure for VW and frequently the effects are fatal, often killing the tree in a matter of days. But with larger, well established maples, the disease seems to be more compartmentalized and only random branches affected. Often, just making sure the tree is well watered (not over watered) and receiving adequate nutrients will be sufficient for it to withstand the disease.

VW needs to be accurately diagnosed by a plant pathologist so taking an affected dead branch into your extension service office is the first step. Be sure you make a clean pruning cut and sterilize your pruners.

I don't have any significant size branch that has been affected, just small branches all through the canopy. It doesn't sound like the disease you describe. Here on the East coast, across New England we had two months without significant rain last July and August and then a warm winter but with times of very cold and windy periods. It seems to be the consensus here that the combination of the drought last summer and the bad winter weather have caused a lot of problems for many gardens. So unless my tree suddenly has a whole large branch die, I'd think the weather circumstances might be the reason for the damage.

So, what you are saying, is if there are dead branches I can reach, I could prune them out, but most of them I won't be able to reach. Just keep it watered and fertilize it? Any idea if the tree will fill in and replace any of the small dead branches?

dead is dead.. it is removed.. nothing good or bad about it.. just do it.. if its safely in reach.. i mean really..if it 60 feet up a tree.. who cares ...but if you can.. do it..

basically.. a clean cut will heal and encapsulate properly protecting the tree for teh rest of its life.. leaving it to rot off..usually means the hole never hesals..and in a decade or two.. tree time... you might be letting water into your heartwood...

sounds like you alleged z6 slipped into a z5... prung out dead wood isnt all that uncommon in my z5

especially if it went into winter rather stressed sue to drought... always try to give you foo plant.. of any kind... an good deep drink in fall... after or during a drought.... and im not talking about 100 foot tall oaks...

ken

" sounds like you alleged z6 slipped into a z5... prung out dead wood isnt all that uncommon in my z5 "

Random stem die back in winter can happen anywhere 'JM's can be grown. It is has little to nothing to do with winter temperatures or cold damage and everything to do with the way these trees produce new growth and shed older, less productive growth.

Eight years ago my JM was just the right shape to catch snow in its canopy and break a number of branches big and small. I was advised to remove the tree but one person said wait and see.

After a few unattractive years it has filled it, regained its original shape and looks good.

Don't give up too soon. As people have advised, get the dead wood out. How it leafs out next year may indicate if it is in decline then you have another decision to make. I know you know fertilizer won't help so don't apply it.