Also note that a lot of the bark is missing from the main trunk thanks to my son's horseplay around the tree. Could that be the cause?

Preen didn't do that!! Preen is a pre-emergent herbicide and has no effect on already established landscape plants like your tree.

Did the browning and wilting happen rather quickly? If so, it's possible the tree has succumbed to Verticillium wilt, a soil borne fungal pathogen that maples are especially prone to but the only way to know for sure if this is the case is to take samples into your extension service office for testing. This is important to determine because VW present in your garden will limit what else you may be able to plant in the maple's place.

It is also possible that bark damage could be the culprit but the decline would be much slower and the bark would have to have been removed fully from around the entire trunk circumference to actually kill the tree.

FWIW, daily watering is likely too much unless you are just sprinkling. In time of drought - and we here in the PNW routinely experience summer drought - a deep, slow soaking once a week is typically more than sufficient. The key to good watering practices is to do so infrequently but slowly and deeply when you do.

Yes, it was rather quick as we were away on vacation for two weeks and came back to find the tree like this.

I will take soil samples around the tree tonight. If it is VW, what is the treatment? Thanks!

Your lawn looks weed free. Did you use Weed N' Feed on the grass?

The missing bark on the trunk isn't enough by itself to kill the tree. As Gardengirl said, it has to be missing all the way around the trunk to kill the tree.

Mike

I have not used the Weed N' Feed product on my lawn.

You need to take in samples of the tree itself for diagnosis. Cut off a decent sized branch right against the trunk and take the entire branch with any leaves attached in for identification of the problem. You can do soil samples as well but they need to go into a soil lab and since the VW pathogen is present in most soils anyway but in a dormant or inactive state, I'm not sure that alone is going to tell you what you need to know.

There is NO treatment for VW other than soil sterilization which is not at all practical for a homeowner. I'd suggest you do some research on it to understand how this opportunistic pathogen works. When it is discovered to be in an active state in your garden, you just need to be very cautious about what you may choose to plant in the area and pick only from VW resistant plants.

"Yes, it was rather quick as we were away on vacation for two weeks and came back to find the tree like this."

Any feuding with neighbors? Malicious neighborhood kids?

Because that almost looks like intentional damage.

Verticillium wilt can be very rapid - almost overnight in some cases. I personally had a JM succumb to VW in just 2-3 days. One day it looked perfectly fine; several days later it looked the photo above and was stone dead!!

Unless something like a liter a bottle of some unknown herbicidal concentrate was applied to the root zone, I can't imagine what sort of deliberate action could be taken to kill this tree that would leave no other signs.

I can't believe no one mentioned it looks exactly like foliar grass/weed killer. I have accidently had drift kill trees like this, and it looked EXACTLY THE SAME! I would ask the neighbors if they sprayed their lawn about that time, I'd bet on it. I realize this is a couple of years old, I would just watch for spraying from now on and cover the new tree if you see any being done.

Actually, herbicidal drift has a much different appearance on an established tree with typically only some foliage deformation. That's why no one mentioned it :-)) It would take concentrated spraying or a direct root application to kill that completely and that rapidly. And anything sprayed on a lawn in concentrations heavy enough to kill the tree would have wiped out the lawn as well!!

I'd bet money on this being Verticillium wilt. It is almost classic VW in its appearance and manifestation and I encounter it frequently in my profession as a consulting horticulturist.

I don't believe that. I have had twelve tomato plants die all at once and all over from drift from next door, also had very bad damage over whole plant from the same drift on some Maximilian Sunflowers. I saw the truck there and the next day they were completely wilted, completely brown and dead within 4 days, The truck was spraying in a strong wind coming my way and was 100 feet away. I could smell it. And how long were the above posters gone?

The topic is Japanese maple trees, not tender non-woody annual or perennial plants like tomatoes or sunflowers!! The reaction to herbicide drift will be very different between the two types of plants. One will react to the herbicide virtually overnight with browning, drying and death. The other will not die unless it is directly sprayed with herbicide and even something like gylphosate or concentrated brush killer will take multiple applications to kill an established woody plant like a tree.

This is not supposition but fact......documented by literature and confirmed by several decades as a professional horticulturist!

You say a lot of the bark is missing on the main trunk thanks to your son's horseplay. Do you have a picture or two. I'm beginning to think that could be the cause. It sure wasn't spray from your neighbor's.

I’m potting several Japanese Maples, is it Ok to use Preen ? Art

HU, just make sure to put them in a fast draining mix like 5-1-1 or gritty mix, and not "garden soil" or dirt from your yard. I use gritty mix and my JM's do well in it.

I concur with gardengal on weeds not being an issue. I probably wouldn't use it myself.