Sources of resistance to Pyrenophora tritici-repentis in bread wheats

Summary No complete resistance to Pyrenophora tritici-repentis has been located in more than 1400 bread wheats examined. Incomplete resistance, however, occurs at different levels in many spring and winter types and data are presented for the strongest sources of resistance detected. In particular, there is a high frequency of Brazilian spring wheats with appreciable levels of resistance to this pathogen. Recent international nurseries from CIMMYT, Mexico, also contain numerous potentially valuable sources of resistance and these wheats may be shorter and higher yielding in Australia than the Brazilian wheats. The resistances in many Brazilian cultivars may be largely common because the cultivars are often strongly interrelated. Some of the Brazilian wheats resistant to P. tritici-repentis are also resistant to one or more of the septoria diseases and/or possess tolerance to aluminium toxicity.