Our Autumn Blaze maples were planted about 15 months ago, in the spring of 2019 by a local nursery.  They are about 9 - 10 feet tall, and big around as a 50-cent piece.  We watered them every week last year.  We have been doing the same this year, turning the hose on them really slow, for about 1/2 hour. 

We live in W. Fargo, in a new development south of 52nd Avenue, so it is new soil for trees - definitely a corn field three years ago.  Very heavy sticky gumbo type soil. When our guy planted them, he put in a lot of lighter mulch however - he didn't just put back the heavy soil originally there. 

The two maples leafed out and seemed to flourish last year.  But then, starting in late June, they turned reddish/brown, first the one in front (east side) then the one in back (west side). 

By July 1, the front maple was entirely reddish/brown, and by July 15 the one in the back had turned too.  They didn't die though, and retained their odd-colored leaves.  But they began to drop them in August, which seemed way too early.

This year, 2020, the two trees have done much the same.  In the front yard, the maple greened up nicely in the spring, but by mid/late June, it was reddish brown.  The one in back has been slower, but is showing the tinge of red/brown now (mid-July).  It seems to me that the south facing leaves were the first to turn (does it have to do with sun, I wonder?).

My nursery guy is great, but he doesn't really know.  He says the soils here are a bit troublesome.  He thinks they will eventually come out of it.  He has recommended against fertilizer so far.  He is right that they put out leaves in the spring and have increased in height.  It's not like they died.

One other bit of info: our neighbor planted his own Autumn Blaze maples from a different nursery last year too.  His did the same thing as ours - turned reddish/brown by midsummer.  I notice his have not done that this year, though.

I appreciate any ideas how to treat them.  Maybe it is just a wait-and-see game.