Bipolaris victoriae (Victoria blight of oats).
Abstract A disease almost unknown prior to 1944 (Romanko, 1957), Bipolaris victoriae is a potentially destructive disease of oats (it reduced the Iowa oat crop by 32% in 1947) (Anon, 1965) that currently has a limited host range and geographical spread. It has been reported from several continents and associated with several crops, however its status as a pathogen on crops could be questioned in all cases with the exception of oats, timothy grass and switch grass. It is seedborne and thus any trade in seed both for cultivation or for livestock feed is a potential means of spread. The virulence of the fungus is due to the production of a peptide often called a host-specific toxin 'victorin'. The disease has generally been controlled through the use of genetically resistant lines but the resistance gene which confers resistance to victorin actually causes plants to become susceptible to crown rust, caused by Puccinia coronata (Lorang et al., 2007).