Going by what I've heard mentioned here many times, don't water an established tree. If you've had a severe drought it may not do any harm, but the tree likely has a large root mass and has adapted long ago to your climate. The problems are likely seperate, but the leaves should be ready to shed now anyway in fall.

If you've had a major drought or the tree is surrounded by pavement that covers most of it's roots so water can't get to them, it would be a good idea.

There's a very good reason to at least consider it.

Winter survivability.

The primary factor in winter hardiness is temperature, so much so that almost nothing else is factored into the zone ratings.

Let us posit that there is nothing you can do about temperature. So what can you affect that can effect a change in winter survivability?

One of the easiest is availability of water through the fall.

" I have personally treated the elm for the dreaded emerald ash borer, trying to keep it at bay."

Is it an elm or an ash?

water the lawn.. good enough ...

have you had decent rains since the drought ended...

if so ... forget about it ...

its been there 27 years... it should be rather able to take care of itself...

more info on treating elm for ash borer ... if its other than a typo ...

ken

Ah yes, the mental slip. It is indeed an ash. In spring I treated it with Bayer Advanced Tree & Shrub Protection.

In our community the street trees are planted in a 3 foot wide slash of soil and grass, with the road on one side and sidewalk on the other.

We had an over abundance of rain in spring, July and August had less rain than average and there has not been a lot of rain in September either.