Contribution of seedborne Blackeye cowpea mosaic potyvirus to disease dynamics and loss of yield

摘要

Blackeye cowpea mosaic potyvirus [bean common mosaic virus] is an important seed-borne pathogen on cowpea. This virus spreads in the field through aphids (Aphis craccivora, Myzus persicae and Macrosiphum euphorbiae) in a non-persistent manner. Sowing seeds (cultivars LV1 and LV2) with 4-10% infection resulted in 65-100% infection at maturity, depending on the variety and crop season. The aphid population in March to May was more than in September to November. All the affected leaves were ELISA-positive. The affected primary leaves of the main stem and the branch showed a high concentration of virus. The concentration of the virus decreased in successive leaves. The seed yield per plant was less in early-affected plants (131 g) than late (1517 g).There were more shrivelled seeds (41.5-47.5%) when the plants were affected early than late (5.0-14.0%). The seeds from plants affected at 10 days old had 9-19% infection, depending on the variety. Seed infection was least (1-4%) in plants infected beyond 60 days, while pooled infected plants had 7-12%.