Hi all. Several years back I had a beautiful flowering plum tree. It developed what looked like black warts on the branches. It spread over the course of maybe three years. The branches it was on died & I removed them. Being tree challenged, I consulted a nursery. They said it was Gall & that I should avoid touching those "things". Apparently fruit trees are susceptable. BTW, this was an ornamental plum. (no fruit) I had the tree sprayed. (to no avail). It died (completely) last year. I also have a weeping Japanese cherry tree. I was told that Gall could spread to that. The Plum is now gone & I'm watching for signs of Gall on the cherry. Does anyone know about this? I've been told numerous conflicting stories (by so-called professional tree people) that I started to think they only wanted the jobs (&my money). Thanks in advance. If I lose the cherry I'll be heartbroken. I planted this tree personally. It's app. 17 yrs. old. BTW, it had a root ball the size of a VW.
I think there's also a forum here for discussing fruit trees--I'm not sure exactly what it's called but you might find people with more experience over there. My thought is that it depends on what caused the gall on the plum tree--there are lots and lots of different kinds of galls caused by lots of different things and I don't think they're usually responsible for killing trees--I could be wrong on this, but I see them on oaks all the time and they look perfectly healthy. Often they're caused by insects and if you find out what was causing it on the plum you can probably take some preventative measures on the cherry. They are both genus Prunus so they are likely to be susceptible to similar types of insects and other problems, this doesn't mean for sure you would have the same thing happen to your cherry, but it wouldn't hurt to figure out exactly what happened to the plum. So I'd try the fruit tree forum or ceejay's suggestion of talking to the extension office is an excellent one too.
Say gloriabythelake, try a search for Apiosporina morbosa with me as the author of the post. Try searching in the Trees and Shrubs Forum. I think that's where this has come up a few times. If you can't find it, D-Mail me and I will take time to type out the low down on this for you so that you can decide how best to deal with it.