Submitted to: Hard Red Winter Wheat Workers Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 26, 1998
Publication Date: N/A
Technical Abstract: From l988 to 1997, there have been many changes in the leaf rust virulence frequencies in the central United States wheat-growing area. Since 1988, the percent virulences of Lr2a and 2c genes have been decreasing, while at the same time the Lr1 and 3 virulence frequencies have remained near 90%. Lr9, 16, 24 and 26 are the most commonly used leaf rust resistant genes in wheat breeding programs. Lr9 and 16 virulence frequencies have been near zero while Lr24 and 26 frequencies have fluctuated between 20 and 50%. Since 1988, there has been an increase in virulence frequency to Lr3ka, 11 and 30. In 1997, there was a significant increase in Lr17 virulence, which was due to an increase in acreage of the cultivar Jagger, which has Lr17 resistance. Lr10 virulence frequency has been consistently above 90% the past 10 years, while virulence to Lr18 has been less than 10 percent. The methods for obtaining longer lasting wheat leaf rust resistance are: 1) pyramid seedling and adult plant genes; 2) find new genes from crosses wit wheat relatives; 3) gene deployment; and 4) genetic engineering.