| Abstract |
In 1950 a stem rust epidemic struck the wheat crop in the United States and Canada, reaching its greatest destruction in 1954. In 1953 the durum wheat crop of the U.S. was 60 per cent destroyed, and in 1954,75 per cent. The primary cause of the disease, called race 15B, was capable of destroying any commercial wheat variety then in commercial use. A race similar to 15B was spreading simultaneously in Latin America. A disaster of this magnitude forced scientists to search for new solutions, and out of this crisis came initiatives which are still benefiting worldwide agriculture. This paper describes one of those benefits. The standard response to a disease epidemic is the rapid testing of wheat lines to identify resistance to the new race of the pathogen; then to multiply seed of the resistant lines, or to cross the resistant lines to "pyramid the genes" for resistance. A race as virulent as 15B demanded the widest possible testing in the shortest possible time. In 1950 the U.S. Department of Agriculture * appealed to seven countries to join the U.S. in testing 1,000 lines of wheat selected from the U.S. World Wheat Collection as possible sources of resistance to 15B; the seven countries were Mexico, Colombia, Ecuador, Peru, Chile, Argentina and Canada. CIMMYT's predecessor organization in Mexico was an active participant. These 1,000 wheats were exposed to the stem rust populations in the participating countries. The results of this 1st International Stem Rust Nursery exceeded expectations and today, much of the stem rust resistance in commercial wheats of the U.S. and other countries can be traced to resistant breeding materials identified from those early international trials. There were other benefits of even greater importance. A new mechanism for widespread distribution and testing of wheat germplasm was in the process of creation. |
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