[1] Zambia Agr Res Inst, Mt Makulu Cent Res Stn, Lusaka, Zambia
[2] Mikocheni Agr Res Inst, Dar Es Salaam, Tanzania
[3] Univ Nairobi, Coll Agr & Vet Sci, Dept Plant Sci & Crop Protect, Nairobi, Kenya
[4] Int Inst Trop Agr, Dar Es Salaam, Tanzania
[5] Texas A&M AgriLife Res & Extens Ctr, Dept Plant Pathol & Microbiol, Weslaco, TX USA