viral disease response trait barley yellow dwarf virus disease resistance 2011-08-19T01:00:45Z TO:0020067 Causal agent: The Barley Yellow Dwarf Viruses, Luteovirus (Group IV (+)ssRNA). BYDV (exact) plant_trait_ontology Symptoms: uneven blotches of bright yellow discoloration on the tips and margins of older leaves, eventually progressing down toward the base, covering the entire leaf within a few weeks. Reduced internode elongation causes stunting with severe infection possibly. jaiswalp