Experimentally the virus can be transmitted by pollen, but since barley is self-pollinated this method of spread is generally of no consequence. Infected seeds produce infected plants. Seed from virus-infected plants is generally infected to a 60 per cent level. Disease builds up when infected seed is planted year after year. Damage Description Symptoms may vary with the virulence of the BSMV strain and time of infection.
Infections appear as chlorotic mottling with spots or stripes of a yellowish color.
Infected plants may be stunted and may mature later than healthy plants. Yield losses are proportional to the level of infection in the seed lot. Losses are caused by reduced grain production, fewer heads per plant, semi-sterility and incomplete head emergence from the sheath. Heavily infected crops have had yield reductions of up to 25 per cent. The percentage of infected seedlings indicates the level of grain infection.