First reports of Phytophthora ramorum mating type A2 in Europe and type A1 in North America
In Europe, Phytophthora ramorum (EPPO Alert List) causes twig blight mainly on Rhododendron, Viburnum but also on various other ornamental shrubs grown in nurseries, parks and gardens. However, P. ramorum has never been observed in forest trees. So far, only mating type A1 had been detected in Europe. In USA (California and Oregon), P. ramorum is causing sudden oak death which is a lethal disease of oaks (Quercus spp.) and tanoaks (Lithocarpus densiflorus). P. ramorum has also been detected in a wide range of trees and shrubs. So far, only mating type A2 had been detected in North America. Two reports are now published simultaneously on the first findings of mating type A2 in Europe (isolate collected in Belgium from a Viburnum bodnantense nursery plant which had been imported but its origin is not given) and of mating type A1 in North America (isolates collected from nursery plants of Viburnum and Pieris in northern Oregon).
Werres, S.; De Merlier, D. (2003) First detection of Phytophthora ramorum mating type A2 in Europe.
Plant Disease, 87(10), p 1266
Hansen, E.M.; Reeser, P.W.; Sutton, W.; Winton, L.M.; Osterbauer, N. (2003) First report of A1 mating type of Phytophthora ramorum in North America.
Plant Disease, 87(10), p 1267