1. Department of Agronomy; Stellenbosch University; Stellenbosch South Africa
2. Western Cape Department of Agriculture; Outeniqua Research Farm; George South Africa
3. Agricultural Research Council Plant Protection Research Institute; Queenswood Pretoria South Africa
4. Department of Soil, Crop and Climate Sciences; University of the Free State; Bloemfontein South Africa
5. Department of Animal, Wildlife and Grassland Sciences; University of the Free State; Bloemfontein South Africa