Abstract
In this paper, we propose a mathematical model that describes the competition betweentwo plant virus strains (MAV and PAV) for both the host plant (oats) and their aphid vectors. Wefound that although PAV is transmitted by two aphids and MAV by only one, this fact, by itself,does not explain the complete replacement of MAV by PAV in New York State during the periodfrom 1961 through 1976; …