Hello to you, I planted two large trees this fall and they are doing so well. They get full sun and I do water them.
Better ask an expert.

Me too. I believe River Birches do well in the wild near streams and rivers. They are used to having lots of water available. In dry times I have let the hose drip on them to compensate for the lack of water. Or it may be that it is too dang hot!

I also have a river birch that is looking sickly. I planted 2 trees 6 years ago and one of the trees produce a minimal amount of leaves compared to the other one. I have sprayed the tree but it is approximately 20 feet tall now and cant reach anymore

It's the time of year when river birches lose their leaves - at least in zone 7 it is. They shed a lot earlier than my other trees every year - usually start around the end of August.

I have three very large river birch and they constantly drop leaves. During drought conditions they really start dropping.
Mike

The tiny third trunk of my year-old river birch never got any leaves, and was drooping, so I tried to tie it back. It snapped, and then I saw it was hollow at the base. I took it all to the garden store, and they said I had a borer pest. Maybe it's the reason there are no leaves on the top of the two good trunks. I bought some Borer pesticide and will spray the tree.

My question is this, I took a soil sample from under the tree, thinking I had a Ph balance issue, and the soil was full of tiny termite worms. I do think the tree was planted where once upon a time huge oaks lived, and their roots are probably still buried far down. Will termites hurt the river birch roots? Should I pour a termite-killing solution around the base, or let them be?

Thanks for ideas ..... Jan