European Mistletoe (Viscum album subsp. album) in Canada. C. E. Dorworth, Forestry Canada, Pacific and Yukon Region, Pacific Forestry Centre, 506 West Burnside Rd., Victoria, B.C. V8Z 1M5. . Plant Dis. 73:444. Accepted for publication 12 February 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0444E.
In September 1988, George Tapley of Victoria, British Columbia (lat.
48° 30' N. long. 123° 20' W) brought to my attention a mistletoe on his
apple (Malus sp.). I identified this as Viscum album L., a plant not
collected before in Canada. The identification was confirmed and the
specimen further specified as a male plant of subspecies album by F. G.
Hawksworth (U.S. Forest Service, Fort Collins, CO). A collection was
preserved in the Pacific Forestry Centre herbarium as DAVFP 23772.
A public request for information and a survey in the now defunct apple
orchards in northeastern Victoria by Forestry Canada. Agriculture
Canada, and the B.C. Ministry of Forests disclosed three infections,
including the first one noted. within 200 m of one another, which werc
probably derived by human transmission from a fourth infection about
2.8 km away. All occurred on Malus sp. According to the residents, the
original infection is more than 37 yr old. V. album was introduced into
North America about 85 yr ago ncar Santa Rosa. Californ ia,
approximately 1.300 km south of Victoria. The parasite now occupies
114 km2 and infects nspecies or hardwoods in California. (1). Presence
of V. album in Victoria demonstrates that climate will not impede
further infection on much of the West Coast, at least as far north as
southern Vancouver Island.