Incidence of Alfalfa Mosaic Virus Infected Plants in Fourteen Alfalfa Cultivars

Alfalfa mosaic virus (AMV) is of particular concern because of its widespread occurrences in most alfalfa fields. It is known to adversely affect yield but the percentages of reduction in alfalfa forage yield due to AMV infection found by many researchers have been quite varied. With 30 million acres devoted to alfalfa production in the United States, even conservative estimates of yield decreases due to AMV infection will result in economic losses that run into millions of dollars. No adequate method has been developed to control AMV in alfalfa. The development of resistant alfalfa varieties would be a desirable means of eliminating or at least reducing yield losses. The objectives of this study were to determine if varietal differences in reaction to AMV existed in an established stand of fourteen cultivars, to test the effect of AMV incidence on yield and stand, and to develop a population of virus free plants to serve as a breeding pool in which selection for promising resistant clones can be carried out