1. Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland, UK
2. Queensland Horticulture Institute, Department of Primary Industries, 80 Meiers Road, In-dooroopilly, Queensland 4068, Australia
3. Department of Plant Pathology, University of Minnesota, 495 Borlaug Hall, 1991 Upper Buford Circle, St. Paul 55108