Control of aphids and barley yellow dwarf virus in spring-sown cereals

The effects of sowing date and the timing of insecticidal applications on the colonization of cereal crops by aphids and incidence of barley yellow dwarf luteovirus were investigated. For three years (1990-1992) spring barley was sown in mid-March and mid-April, and one to three sprays of pirimicarb were applied prior to stem elongation. In 1990, yield declined with increased virus incidence; spray treatments just prior to stem elongation were most effective in aphid control but the benefit was short-lived. In 1991 and 1992, aphid migrations were relatively late, virus incidence was low and the sprays had no significant effect on aphid or virus abundance. Yields from early-sown plots were significantly greater than from plots sown late in all 3 years. Results suggest that spray regimes aimed at controlling aphids carrying BYDV into spring-sown crops are of little benefit and should be discouraged. In cases where some form of control is needed, appropriate timing of insecticide sprays depends upon the timing of aphid migrations relative to crop development and the infectivity of aphids migrating in the spring. Copyright (C) 1996 Elsevier Science Ltd.