The susceptibility of barley cultivars to barley yellow mosaic virus (BaYMV) and its fungal vector, Polymyxa graminis

Abstract

SUMMARY In glasshouse experiments, barley seedlings were inoculated with barley yellow mosaic virus (BaYMV) either mechanically or by using zoospores or cystosori of a viruliferous isolate of the vector, Polymyxa graminis , maintained on barley in sand culture. Experiments using mechanical inoculation showed that seedlings became more resistant with age. Consistent cultivar differences were obtained: cvs Maris Otter and Halcyon were very susceptible and cv. Athene seemed immune. Symptoms developed more rapidly at 23 than at 17 or 11 o C. After vector inoculation, symptoms developed more slowly than after mechanical inoculation but cultivar ranking was similar. Cultivars did not differ in susceptibility to the vector, as measured by zoospore production on their roots. Spring barley cultivars supported the growth of the vector which remained viruliferous and some showed symptoms although, in the field, symptoms do not appear on spring‐sown crops.