Epidemiology of cereal aphids on winter wheat in Norfolk, 1979-1981.

Abstract

1. The cereal aphid outbreaks of 1979 (Metopolophium dirhodum) and 1980 (Sitobion avenae) and their lower population levels in 1981, in Norfolk, are described.
2. The high incidence of cereal aphid outbreaks in Norfolk are probably due to a combination of factors, including: the high hectarage devoted to cereals; the low numbers of aphid-specific and polyphagous predators present early in the season; and the dry conditions during the immigration period.
3. It is suggested that monitoring for M. dirhodum could be carried out on roses in the spring, while a forecasting scheme for S. avenae can only be developed when a greater understanding of its life cycle is obtained.