Effect of Spring Black Stem on Yield and Growth of Alfalfa in the Greenhouse. Edgardo H. Hijano, Ingeniero Agrónomo, Plant Pathologist, Alfalfa Project FAO-INTA Arg. 75/006, Manfredi Agricultural Experiment Station, 5988 Manfredi, Argentina. Plant Dis. 65:725-726. Accepted for publication 23 December 1980. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-725.

The effect of spring black stem on the yield and growth of alfalfa was evaluated after artificial inoculation of Phoma medicaginis var. medicaginis in a greenhouse. Leaves and stems inoculated simultaneously produced 44% less dry forage than the uninoculated control. Inoculation of leaves or stems separately produced 32 and 21% less dry forage, respectively, than the uninoculated control. Inoculation of leaves and stems simultaneously, leaves separately, and stems separately caused reductions of 26, 9, and 17%, respectively, of alfalfa growth measured as stem elongation 15 days after inoculation.

Keyword(s): Medicago sativa.