Black Galls

[pyrcp]

I have several trees in my yard with large black galls either on branches or high on the trunk above the lowest branches. I'm not sure what kind of trees they are (could be several varieties), but they are not fruit trees; although there are fruit trees in the yard as well.

I had 1 opinion that the cause is a fly that leaves it's larve in the tree and that subsequently causes the gall or a disease that leads to galls.

I have several questions.

What do I do with the infected trees? Trim only the branches? Cut down the trees where the trunk is impacted? Cut down any tree infected no matter how minor? Nothing? Spraying?

How do I protect the uninfected trees?

Would it be safe to replant trees in the yard?

 

[underwor]

My first guess would be black knot disease. This affects many members of the prunus genus. In this area chokecherry, Canada red cherry and Mayday trees. It is a fungus that causes it. Best treatment is to cut them off during the dormant season and burn them. Cut 4-6" below each knot so that you get most all of it. Look for black knot on the search engines to confirm. If it is aspen trees, then it is another fungus. Let us know.

Bob