Management of yellow mosaic‐inducing viruses on barley by selection of resistant cultivars1

Abstract

During the last ten years yellow mosaic of barley has been spreading more and more in European countries and in some infested areas yield loss can only be prevented by growing resistant cultivars. Breeding of such cultivars is one of the most important goals of small‐grain breeders. To select resistant cultivars, several methods are available such as mechanical inoculation, growing of plants in infested soil in the field or in growth chambers as well as using root powder of infected plants. The situation has recently been complicated by the discovery that yellow mosaic is caused by at least two distinct but closely related viruses (barley yellow mosaic virus and barley mild mosaic virus). Inoculation methods are not equally effective for these two viruses. Although it appeared initially that resistance to the two viruses was linked, there are now indications that some barley cultivars respond differently, and there may even be a third virus involved. Programmes for selection of resistant cultivars now have to take account of this.