1. Agricultural Research Council–Grain Crops, Private Bag X1251, Potchefstroom, 2520 South Africa
2. Agricultural Research Council–Vegetable and Ornamental Plants, Private Bag X293, Pretoria, 0001 South Africa
3. Unit for Environmental Sciences and Management, North-West University, Private Bag X6001, Potchefstroom, 2520 South Africa
4. Department of Plant Pathology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa