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Paper

Written Paper

Resistance to leaf and stem rusts in wheat  [1988]

Roelfs, A.P. (Minnesota Univ., Saint Paul (USA))

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Although the cereal rusts have been able to overcome many of the resistant cultivars developed during the past 80 years, many of the resistant cultivars have been successfully grown on large areas. Stem rust has been controlled by the use of resistance combinations that include Sr2 transferred to Hope and H-44 from emmer by McFadden in 1923. Sr26 (from Agropyron elongatum), Sr31 (Secale cereale), and Sr36 (Triticum timopheevii) seem to be the most effective single gene resistances worldwide. Thatcher (resistance from T. durum) developed by Hayes et al. in 1934, also has a useful level of resistance in most areas. Leaf rust has been successfully controlled by combination of Lr13 and 34. These resistances were first used in the cultivars Frontana (Brazil 1934) and Americano 44D (Uruguay 1918). This gene combination continues to be used in recent durable cultivars Chris, Era, Ciano 67, Pavon 76, etc. Assumptions about the genetics and durability of some types of resistance has hindered selection and development of resistance cultivars