Q. We had a cedar elm tree die of hypoxylon canker. The arborist involved made it sound like that there was nothing to do to protect the other trees in the vicinity from becoming infected. That cannot be right can it?
A. I am afraid that is pretty much correct. The disease infects trees that are growing in poor conditions and are stressed. A disease organism exists but infection is related to the lack of water and good growing conditions rather than any kind of spread of the organism from one tree to another. A new irrigation program may help to prevent more trees in the vicinity developing the disease and dying but there is no guarantee.