| Summary report - - 1963 of the international wheat
rust testing centre Njoro, Kenya by HENRY ENNS, K. W. LYNCH and F. F. PINTO Plant Breeding Station, Njoro, Kenya Contents General Acknowledgements Appendix A - Rust scores of the best selections from part of the World Collection of Wheat, Beltsville, Maryland, U.S.A. Appendix B - Colombian breeding material from Dr. C. F. KRULL. Appendix C - Performance of collections of wheat lines and varieties contributed by individuals. Appendix D - Retesting of the best material tested in 1962. Appendix E - Durum wheats from Dr. K. L. LEBSOCK. General Wheat rust infections in the main wheat growing area of Kenya were not particularly severe in the 1963 growing season. However, the rust nursery at Njoro was surrounded and interlaced with susceptible varieties which were sprayed with a mixture of the following races of stem rust: 11, 15, 21, 34, 40A, 40C, 40D, 40E, 40F, 40G, 40T, 117, 143, 184, 295, 296 and 297. (In Kenya race 40 is divided into biotypes A to G and T on the basis of supplemental variety reactions in addition to the standard set of differentials.) Samples taken from various parts of the Njoro experimental area showed that the following races became established: 21, 34, 40C, 40E, 40F, 40T, 117, 184, 295 and 296. The level of infection in the nursery was excellent. Many entries received scores of 80-100% and a few entries succumbed entirely. The infections of brown leaf rust and stripe rust were due to naturally occurring inocculum. Both of these species of rust are generally present at Njoro, with stripe rust especially becoming more severe in the higher altitudes. The race picture for leaf and stripe rust is not known since the main concern is stem rust. The scoring for rust follows the established system used for the International Spring Wheat Nursery, as defined by Dr. W. Q. LOEGERING, U.S.D.A., Beltsville, Maryland. The severity of attack is denoted by the percentages 0, trace (t), 2, 5, 10 and by 10's up to 100. Reaction type is denoted by the letters VR, R, MR, MS, S and VS. Most of the entries were scored for stem, leaf and stripe rust. |
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