Plum Tree Disease / Insects?
My young plum tree (4 years) has large sap blobs and mangled new growth leaves, in very regular spots - at the crotch of each new growth & branch. I assume this is a fungal disease because the ugly gray of the leaves? But I also start to think maybe borers because it's so methodical, as if at each sheltered area where a larvae entered? Any suggestions on treatment? There are a number of these little insects under almost every leaf, but they don't look like the pics of peach borers I see online. Thanks
Multnomah County Oregon
Thank you for your question. There does appear to be a pathogen at work, but I suspect it is the bacterial one described here: https://pnwhandbooks.org/plantdisease/host-disease/prune-plum-prunus-spp-bacterial-canker Since there are no effective chemical treatments, it may be a matter of time before you lose the tree, but trying some of the other recommendations might stem that. I think the insect is just there for the food, and not an actor in the tree’s decline.
Thanks. The tree is between two other plum trees of the same age that don't show any signs of infection. Obviously I don't want them to be. Do you think it's smarter to remove the tree now so it doesn't spread, or see how it's doing by the end of summer?
Were it my tree, I would not keep it and risk losing the other two, as well. Good luck!