VIEW ARTICLE

Disease Detection and Losses

Yield Reductions in Soybeans Infected With Cowpea Mosaic Virus. Pornpod Thongmeearkom, Graduate research assistant, Department of Plant Pathology and International Soybean Program, University of Illinois, Urbana, IL 61801; E. H. Paschal II(2), and Robert M. Goodman(3). (2)Assistant professor, Department of Agronomy and International Soybean Program, University of Illinois, Urbana, IL 61801, Present address: Texas A&M University Agric. Res. and Ext. Center, Route 5, PO Box 784, Beaumont, TX 77706; (3)Assistant professor, Department of Plant Pathology and International Soybean Program, University of Illinois, Urbana, IL 61801. Phytopathology 68:1549-1551. Accepted for publication 6 June 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1549.

Soybeans (Glycine max ‘Improved Pelican’) were mechanically inoculated at the primary leaf or midbloom stage with a soybean isolate of cowpea mosaic virus (CPMV) in field trials at Isabela, Puerto Rico. Yields from treatments with 25, 50, 75, or 100% of the plants inoculated were measured and compared with yields from a noninoculated treatment. In three experiments (planted on 29 December 1976, 13 May 1977, and 1 July 1977), statistically significant (P = 0.01) yield reductions were observed when 50% or more of the plants were inoculated at the midbloom stage. In one experiment (planted 29 December 1976), yield reductions were statistically significant (P = 0.05) when 25% or more of the plants were inoculated at the primary leaf stage and (P = 0.01) when 50% or more were inoculated at the primary leaf or midbloom stage. Correlation coefficients between disease incidence and yield were significant (P = 0.05) for inoculation at the primary leaf stage in two of three experiments and for inoculation at the midbloom stage in all experiments.