The percentage of plants infected with barley yellow dwarf virus (BYDV) was determined in each of 45 New Zealand ryegrass pastures during the summer of 1975#x2013;1976. Incidence of BYDV infection was extremely variable in pastures of similar age, but 1- to 2-year-old pastures generally had fewer infected tillers than did older swards. Many 6- to 30-year-old pastures had over 50 of plants infected with BYDV. Highest virus infection was 84 in two perennial ryegrass pastures aged 8 and 15 years. Pastures at Palmerston North had a slightly higher incidence of BYDV than those at Kaikohe and Lincoln. Pastures in the far south of the South Island appeared to have a low incidence.
展开▼
