Fusarium diseases of wheat

Fusarium graminearum, F. culmorum and F. pseudograminearum are among the dominant species that cause head blight (FHB) and crown rot (CR) of wheat and other small grain cereals. The three phylogenetically related species have different reproductive strategy, ecological niche and pathogenic fitness. Homothallic F. graminearum mainly causes FHB, heterothallic F. pseudograminearum mainly causes CR and the asexual F. culmorum causes both FHB and CR. Populations of all three species have high level of variation in genotype and aggressiveness, but no clear-cut pathogenic specialisation into races attacking specific varieties. Varieties resistant to one Fusarium species are generally resistant to all. Until recently, FHB has been managed using cultural means such as crop rotation and/or chemical sprays. Varieties with high level of resistance have only recently been developed in the USA and Europe. In the absence of resistant varieties, CR management has relied on inoculum reduction using cultural and other means. New sources of CR resistance have recently been discovered, however it will be some years before this is widely available in commercial varieties. Despite all three Fusarium species capable of causing both diseases, resistance to FHB is not linked to CR resistance.