Submitted to: Biennial Workshop on Smut Fungi
Publication Type: Proceedings
Publication Acceptance Date: 5/15/2002
Publication Date: 6/16/2002
Citation: GOATES, B. REACTION OF U.S. SPRING WHEAT CULTIVARS TO KARNAL BUNT. NATIONAL AMERICAN PHYTOPATHOLOGY MEETINGS. 2002.
Technical Abstract: Although overall yield or quality losses due to KB Karnal bunt (KB) in the U.S. and other parts of the world are insignificant, numerous countries have strict quarantines for the pathogen making KB a significant trade issue. Understanding the relative susceptibility of wheat cultivars enables management decisions, which can reduce disease, help prevent disease spread, and reduce the potential for contaminating shipping channels. For three consecutive years beginning in 1997, 140 cultivars representing all market classes were screened. The 50 most resistant lines were screened for an additional year. For each entry and year, 10 spikes were boot injected with a suspension of sporidia in each of 2 planting dates. At maturity individual spikes were harvested and the kernels from each spike were examined for infection. The percent infected kernels of the 10 spikes from each entry, planting date, and year, were averaged to produce mean percent infected kernels per entry. Mean percent infected kernels among 56 hard red, 3 hard white, 5 soft red, 15 soft white, and 26 durum cultivars ranged from 0 to 40.6%, 5.8 to 42.0%, 1.8 to 25.3%, 2.0 to 36.4%, and 0 to 29.4% respectively. The range of infection in the breeding lines was similar. Among all bread wheat and durum cultivars, mean infection averaged 15.8% and 8.3% respectively. Examination of the pedigrees from the most resistant hard red cultivars indicated that resistance might be derived from the cultivar 'Thatcher'. A significant proportion of the parentage of the cultivar 'Chris' is derived from 'Thatcher'. 'Chris' has been demonstrated to carry a single dominant gene Kb1 suggesting that Kb1 is responsible for resistance in several of the best U.S. cultivars. In the most resistant durum cultivars, 'Edmore' is a common parent, suggesting that a component of this cultivar is contributing to resistance. A summary of all data is available on request.