What is verticillium wilt?
Verticillium wilt is a fungal disease that affects elm and maple. Sudden wilting and yellowing are the most distinguishing external symptoms. Internally, if the bark is peeled away from the wood tissue, there should be conspicuous coloured staining of the outer sapwood. The fungus can live in the soil and is thought to be the main route of infection, however trees can catch the disease when introduced into the vascular system through wounds make in the stem tissue. Visual symptoms of verticillium wilt are similar to that of Dutch elm disease. What can I do if I think my tree has verticillium wilt? If you suspect that your city or private elm may have verticillium wilt, please contact the City of Saskatoon, Parks Branch immediately at 975-3300. City crews will take a sample of your tree and have it tested at the provincial lab.
Verticillium wilt is caused by the soil-borne fungi Verticillium dahliae and V. albo-atrum. Both infect a very wide range of garden plants through the roots and then grow upwards in the water-conducting tissues, causing wilting of the upper parts due to water stress. Wilting is mostly seen from spring until autumn. Plants most often affected include Chrysanthemum, carnation, aubergine, potato, tomato, cucurbits and strawberries. Woody plants are also affected, including Acer, Cotinus, Rhus, Berberis, Catalpa, Cercis and Rosa, but the full host range is very wide indeed. Conifers are not affected. The most commonly affected plants recorded by the RHS Pathology Laboratory are Acer, Cotinus, Catalpa and strawberries.
