Effect of Anthracnose (<i>Colletotrichum trifolii</i>) Infection on Yield, Stand, and Vigor of Alfalfa¹

Abstract

Relatively high levels of field resistance to anthracnose, Colletotrichum trifolii , were observed in the alfalfa variety ‘Cherokee’ and in an experimental line MSHp6. Severe anthracnose infection on susceptible varieties, ‘Saranac’ and ‘Iroquois,’ caused 25 to 30% losses in forage yield and stand, as well as losses in plant vigor the following spring. We believe that the importance of anthracnose injury in warm humid areas has been underestimated. Resistance in Cherokee and MSHp6 was attributed to recurrent cycles of field selection in North Carolina and Maryland, respectively, where anthracnose often occurs.