Bamboo growth threatening tree
We have a black bamboo plant on our property that has spread under our fence and is sending up shoots in our neighbors yard. The bamboo is growing under a large, well-established tree on their property. I believe the type of tree is a myrtle. Their tree is not doing well. The leaf structure is very sparse. They believe the problem may be caused by the bamboo "strangling" their tree. Could this be the case? This a very large mature tree and there have not been many bamboo canes in their yard. The bamboo is also surrounded by other plants (rhododendrons, magnolia tree, other shrubs) and none of these have shown any signs of stress. If the bamboo is killing the myrtle tree, I will remove it, but I want to make sure this is the problem before I take any action. Thanks. John Payne
Marion County Oregon bamboo
Black bamboo (Phyllostachys nigra) may or may not be the cause of the decline of your neighbor's tree--but established black bamboo can spread quickly, and it is your responsibility as its owner to control your bamboo and keep it in your own yard. Even if there are only a few culms in their yard now, there will soon be many more.
Retro-active control of bamboo, especially large bamboo, is not easy. To eliminate individual culms, trace their underground connecting root back to inside your property, and sever it. Otherwise cut-and-stump-spray of the cut invader will poison the original clump. Not enough to kill it, probably, but enough to damage its appearance. And meanwhile the misplaced cane will probably resprout in your neighbor's yard.
Long term you will need to do now what should have been done at the time of originally planting: dig a trench 30" deep completely around the desired perimeter of the clump, and set in a 30" wide strip of 80 mil "bamboo barrier" plastic, available online or from any nursery that specializes in bamboo. HINT: dry ground is much more difficult to dig than moist soil. Run a soaker hose for a day or two over the exact location where you are going to dig.