Resistance of Dollard Red Clover to the Pea Aphid, Macrosiphum pisi1

Abstract

Plants of the Dollard variety of red clover, Trifolium pratense L., were more resistant to the pea aphid, Macrosiphum pisi (Harris), than plants of the Wegener variety. Resistance in Dollard was owing to nonpreference and antibiosis. This resistance to aphids appeared to explain a much lower incidence of virus in Dollard than in Wegener when these varieties were grown under field conditions at St. Paul, Minnesota. When the mosaic and pea stunt viruses were inoculated mechanically, Dollard was just as susceptible as Wegener. Breeding red clover for resistance to aphids may be a more successful approach than trying to breed for resistance to virus diseases.