Barley Yellow Dwarf Virus Strain Incidence in Small Grain Cereals in Northeast Spain

Barley yellow dwarf virus (BYDV) was detected in forage cereals and small grain cereals by indirect enzyme-linked immunosorbent assay. Samples of forage cereals collected in the winters of 1987/1988, 1988/1989 and 1989/1990 showed that this crop is a reservoir of BYDV during the end of summer and autumn. PAV-like and MAV-like isolates, in single or mixed infection, were the most common. The proportion of isolates in the infected samples was relatively stable, Samples of winter cereals collected in the springs of 1988, 1989 and 1990 showed that PAV- and MAV-like isolates were widespread. The proportion of samples infected with PAV-like isolates was much more variable than that of MAV-like isolates. The incidence of PAV-like isolates in winter cereals is more dependent on the population of Rhopalosiphum padi during the winter and early spring, than is the incidence of MAV-like isolates on Sitobion avenae density. In northeast Spain (Lleida basin) forage cereals are a constant source of PAV- and MAV- like isolates from which BYDV inoculum is introduced into winter cereals.