Legal question about neighbor's tree

[ToxicShock]

Just a quick legal question for any of our attorney's on the board. Our house backs to an ally. The neighbor on the otherside of the ally has a HUGE cottonwood tree that hangs over the ally but not quite in our backyard. This tree is dumping pollen all over our backyard. It's caused our 5 year old daughter to break out in hives and is clogging our AC. They are selling their house and have moved out so it is currently unoccupied. Could I have some tree guys come out and trim the tree back from the ally so hopefully the pollen won't fall in our backyard without asking permission or do I need to try to get in touch with these people before trimming the tree? Thanks for any advice. I wanted to go "treaty oak" on this thing but the wife wouldn't let me.

 

[CottonEyedHorn]

I'm no lawyer, but here in Plano they are pretty strict about tree branches hanging over the alley, at least to the point where they are in the way of trash trucks, etc. Not sure but maybe you could involve the city and their code enforcement? Here's Austin's code on trees:
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