VIEW ARTICLE

Incidence and Effect of Alfalfa Mosaic Virus on Alfalfa. Pat Crill, Assistant Professor of Plant Pathology, University of Florida, Gulf Coast Experiment Station, Bradenton, Florida 33505; D. J. Hagedorn(2), and E. W. Hanson(3). (2)(3)Professors of Plant Pathology, University of Wisconsin, Madison 53706. Phytopathology 60:1432-1435. Accepted for publication 16 April 1970. DOI: 10.1094/Phyto-60-1432.

Sixty-six percent of 349 alfalfa plants collected in Wisconsin during 1966-1968 were infected with mechanically-transmissible viruses. Alfalfa mosaic virus (AMV) was found in 59%. The AMV isolates were placed in 35 groups on the basis of differential host reaction. When 587 symptomless alfalfa plants from three widespread areas in Wisconsin were studied, 63% of the plants from 2-year-old stands and 78% from older stands were shown to contain mechanically-transmissible virus. Yields of alfalfa hay were significantly reduced by AMV. There was no significant evidence indicating that alfalfa plants exhibiting AMV symptoms were more readily winterkilled than symptomless plants.