Sadly we had to bid our largest plum tree a fond farewell. It had these terrible growths. The local plant nursery said it wouldn't hurt the tree but the fruit this year was half the size as normal and the warts had grown on every branch.
The tree was also at the top edge of our garden and shaded our asparagus patch so badly that they wouldn't produce as well as they need.
The warts were spreading to our other plum trees so we decided it needed to go. And strangely when we cut it, the wood inside stunk...like something dead. Since we cut it, the asparagus has begun to come back in that area of the bed that was shaded. But it looks so strange to not see that old tree there.