02070naa a2200205 a 450000100080000000500110000800800410001910000150006024500960007526000090017130000160018052014790019665000110167565000090168665300240169570000160171970000150173570000200175077300940177010413772019-10-08       2008    bl uuuu     u00u1 u    #d1 aGERMAN, S.  aBreeding for resistance to barley leaf rust in a highly favorable environment for diseases.  c2008  ap. 767-773.  aAbstract Barley leaf rust, caused by Puccinia hordei,has been present generally at low incidence for over 20 years in Uruguay. During 2005 and 2006, the disease reached epidemic levels, causing heavy losses in grain yield and grain size in susceptible cultivars if chemical control was not used. The increase in importance of the disease was associated with the appearance of a new race of P. hordei, virulent to widely grown barley cultivars. The P. hordei population is relatively stable in the Southern Cone of America, only three races having been identified since 1995. The third race acquired virulence on Rph9.z, which is probably present in Defra-derived cultivars, widely used in Uruguay and Brazil. Sources of resistance, mostly adult plant resistance identified since 1999, have been routinely used in crosses in the barley breeding program of the Uruguayan National Institute for Agronomical Research (INIA)for the last 10 years. Combining information from field nurseries and seedling infection type data allowed identification of highly effective resistance, expressed as low levels of disease under heavy leaf rust epidemic challenge. The resistance of these materials derives from European germplasm. The number of resistant advanced lines increased significantly after three cycles of selection for resistance under heavy disease pressure during 2004?2006, which indicates that an important genetic advance in breeding for leaf rust resistance was achieved.  aCEBADA  aROYA  aRESISTENCIA A ROYAS1 aPEREYRA, S.1 aCASTRO, M.1 aDIAZ-LAGO, J.E.  tInternational Barley Genetics Symposium,10.,Alexandria, Egypt: ICARDA, Proceedings, 2008.