STUDY OF THE HOST-WHEAT PLANT RESISTANCE TO CEREAL APHIDS AND ANTI-FEEDING EFFECT OF CYCOCEL ON GREENBUG

Three trials were conducted at North Dakota State University in 1983. Two trials were to screen some Egyptian wheat varieties for resistance to greenbug [Schizaphis graminum (Rondani)] and oat bird sherry aphid (Rhopalosiphum padi (L.) ), and the third trial was to test cycocel for its antifeeding effect on the greenbug. The data revealed that "Largo" and "Amigo" were resistant to biotype C, of the greenbug. All Egyptian varieties were highly susceptible to greenbug but "Sakha 8" and "Daker 52" exhibited a modest level of resistance. The bread wheat varieties "Giza 157", "Giza 155" and "Sakha 8" were tolerant to R. padi. Also the durum varieties "EDM" and "Stork's" were moderately tolerant. The greenbug toxicity caused reduction in plant height, total leaves dry matter and growth rate during infestation, and increased dead tissue dry matter percent. Meanwhile, R. padi reduced the growth rate during infestation and increased dead tissue dry matter percent as demonstrated by correlation study. Cycocel treatments caused decrease in greenbug effect score and plant height, and increase in number of tillers per plant.