"David Hill" wrote in message ...
"............and I have noticed a lot of red spider mites one
month ago in the garden. I have not seen a big quantity around the tree and
along the trunk (two or three), so I was not worried. But now, I am
........."

I have my doubts about them being Red Spider.
If they are bright red, about half the size of a pin head and moving fairly
fast then they are red mites, and are in fact a predator of the red spider.
Red spider are a dull brick red and very hard to see with the naked eye,
they are mostly found by the presence of their web.

Well I have no proof they are the cause of the problem. They are
bright red and move fast. Some plants in the garden seem to be eaten
quite a lot too(photinia for example).

My tree is dying. In a park nearby, I saw a couple of similar trees
with the foliage turning yellow too, but not as much. Both older and
younger trees seem to experience the problem, and moreover at
different places.

Looks like a pest problem to me, a weather-related problem would not
cause that much damage. Can't think about any other reason with
regards to the information I gathered so far.

Any recommendation before it is too late ?