This unhappy native white alder, Alnus rhombifolia, had been deteriorating for quite a while. White alders do not last long even in the wild. A few nearby have already been removed. This one is next. They were nice and shady when the landscape was new. Nicely maturing sycamores and a bigleaf maple can take over for this one now.
As bad as it looks, this nasty stain had nothing to do with the imminent doom of this tree. It developed only recently, and very quickly. It is not nearly as bad as it looks. If the tree were not to be removed, it could survive with this problem for quite a while. Other healthier trees can live with it for many years or indefinitely, and some actually recover.
It is ‘flux’. More specifically, it is slime flux, which is also known as bacterial wetwood. The obvious symptoms are this unsightly bleeding and staining. A less obvious symptom is the swelling that caused the fissure in the bark from which the unsightly fluid is draining. The fluid can smell nasty!
Furrows in the bark develop naturally as the trunk expands over many years. They do not penetrate through the bark into the cambium below.
Fissures are fractures that penetrate through the bark and into the cambium. The fissure in these pictures developed so recently that the orange interior of the bark has not oxidized to tan or gray yet. The fissure is about six inches long, and slightly lower than a doorknob.
Even for healthy trees, there is no remedy for slime flux infection. It can only be left to do whatever is going to do. It can accelerate internal decay, but is otherwise not as detrimental to the health of an infected tree as it would seem to be.
(The article from my weekly gardening column that is typically posted on Thursday was posted yesterday, which is why this article, which is more appropriate for Wednesday is posted today.)