The insects Metopolophium dirhodum (Walk.) and Sitobion avenae (Fab.) appeared in 1967 and 1971, respective!y, for the first time in Chile. From that time on, these aphids have. attacked the wheat, every year in the north central part of the chilean territory.
In order to study the incidence of the virus, the yield and hectoliter weight of the varieties studied at the experiment station "La Platina", Santiago, Chile, from 1966 to 1976, were analysed. It was concluded that: 1966 was a year free from aphids and virus; 1967 and 1968 were affected by aphids but not by virus; from 1969 to 1972 the virus h ad no effect; 1973 showed important virus influence on yields; 1974 had a clear, although unimportant, virus damage; 1975 showed the highest virus losses; 1976 was similar to 1973.
A high corre!ation was found between hectoliter weight and yield in the wheat varieties trials at "La Platina" in 1975 and 1976.
|1Ing. Agr., Ph. D., Programa Cereales, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA), Casilla 5427, Santiago, Chile.|