| Four thousand selections from the World Collection of Wheat, Beltsville,
Maryland, U.S.A., were tested for rust reaction in 1963. These lines and
varieties were taken from the range of P. I. numbers 166,260 to 193,936.
Several hundred of these lines proved to be winter wheat, so that their
stem rust scores were probably not very meaningful. The list of entries
in Appendix A includes only spring wheat. Of the 4,000 entries tested, less
than 30 (not counting duplicates) had infection levels for stem rust of
10% or less. Seven entries had trace infections only but with a susceptible
reaction type in each case. Appendix A shows a list of 185 lines and varieties which exhibited stem rust infections of 30% or less. The latter portion of the appendix (below the solid line) includes an additional 30 selections which had trace or zero scores for both brown leaf rust and stripe rust. The number of entries with trace or zero scores for leaf and stripe rust was considerably greater than the number of entries with low stem rust scores. Appendix B shows a selection of the resistant lines selected from the Colombian breeding material. The total number of lines tested was over 1600, 59 of which are listed. Many of these are dwarf types and have other good agronomic characteristics. Their general adaptability to Kenya conditions is quite good. They are being grown again in 1964 and more data on their performance will be reported next year. Appendix C includes a number of smaller collections of wheat received from individuals. These collections generally exhibited less stem rust resistance than desirable. However, a number have good resistance to both leaf and stripe rust. The collection from Dr. N. E. BORLAUG is an exception in that it displayed very good stem rust resistance. Appendix D lists the varieties that have been tested in both 1962 and 1963. The comparison between the scores of varieties for the two years shows that infection levels do change from year to year. However, this list includes much material with good levels of resistance as well as agronomic characteristics. Appendix E presents a list of the most resistant varieties of durum wheats received from Dr. K. L. LEBSOCK. The level of resistance to stem rust among these varieties is excellent. Many of them, however, fall down on resistance to leaf and stripe rust. |
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