Otto, Harley J.Ford, J. H.Leuschen, W. E.Smith, L. J.Warnes, D. D.2019-09-182019-09-181976https://hdl.handle.net/11299/2069911 online resource (PDF, 2 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu.enReport