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Survival of Verticillium albo-atrum in Alfalfa Tissue Buried in Manure or Fed to Sheep. H. C. Huang, Plant Pathologist, Agriculture Canada Research Station, Lethbridge, Alberta, Canada T1J 4B1. R. Hironaka, Animal Nutritionist, Agriculture Canada Research Station, Lethbridge, Alberta, Canada T1J 4B1, and R. J. Howard, Plant Pathologist, Alberta Horticultural Research Center, Brooks, Alberta, Canada T0J 0J0. Plant Dis. 70:218-221. Accepted for publication 19 September 1985. Copyright 1986 Department of Agriculture, Government of Canada. DOI: 10.1094/PD-70-218.

A study was carried out to determine the survival of Verticillium albo-atrum in diseased alfalfa tissue when buried in manure or fed to sheep. Alfalfa stems naturally infected with V. albo-atrum were buried in indoor cow manure packs and in an outdoor manure pile. Stems were recovered at intervals over 6 wk and examined for viable V. albo-atrum in the tissue. The rate of survival of V. albo-atrum in the stems buried 10, 30, or 60 cm deep for 1 wk was 026%, but it was 5490% in the stems buried near the surface of the manure pile. In the outdoor experiment, V. albo-atrum was viable in 93% of the stems near the surface of the manure pile after 6 wk. When alfalfa hay infected with V. albo-atrum was fed to sheep, the pathogen was present in feces collected within 2 days. The maximum number of Verticillium propagules in sheep feces collected each day was 19 and 29 per dung ball for the experiments in 1982 and 1983, respectively. V. albo-atrum did not persist in the digestive tract and was absent in feces collected two or more days after the animals were returned to a diet free of the pathogen.