Wilt Disease of Norway Maple
Q. My neighbor has a lovely red Norway maple. The city inspector wants to cut it down saying it has wilt infestation. To me it looks very healthy. It is about six or seven years old. How does the inspector determine this kind of disease and how can get evidence? I do not want the tree cut if it has a chance to survive. Isabella Kates - Ontario, Canada
A. They have probably diagnosed Verticillium Wilt. Usually you see outward signs of stress first, like reduced leaf size or wilting of leaves when there is no drought. The strongest indicator is then looking in at the wood, which usually becomes discolored from the infection. Your own University of Guelph has a very nice document http://www.uoguelph.ca/pdc/Factsheets/PDFs/007VerticilliumMaple.pdf on the disease which should help you solve this yourself. At least you will be able to converse with the city inspector and have some knowledge of what he is talking about.