EFFECTS OF THREE SPECIES OF APHIDS ON BARLEY, WHEAT OR OATS AT VARIOUS STAGES OF PLANT GROWTH

Abstract

The greenbug, Schizaphis graminum (Rondani), the English gram aphid, Macrosiphum avenae (Fabricius) and the corn leaf aphid, Rhopalosiphum maidis (Fitch) were tested in growth cabinets on Parkland barley, Selkirk wheat and Rodney oats at various stages of plant growth. The corn leaf aphid did not establish large populations on wheat or oats, but most seedlings of barley infested prior to heading were killed. After barley plants had headed out there were no reductions in yields of harvested gram. The greenbug and the English grain aphid severely injured or killed seedlings of barley, wheat and oats, and caused reductions in kernel weight of harvested gram, even when placed on plants in advanced stages of growth. The need for chemical control of aphids on cereal grains is discussed.