Discovery of a Mycoplasmalike Organism Associated with Diseased Soybeans in Mexico. Jacqueline Fletcher, Department of Plant Pathology and International Soybean Program (INTSOY), University of Illinois at Urbana-Champaign, Urbana 61801. Michael E. Irwin, Agricultural Entomology and Intsoy, University of Illinois at Urbana-Champaign and Illinois Natural History Survey, Champaign 61820; O. E. Bradfute, Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691; and Gustavo A. Granada, Department of Plant Pathology, Instituto Colombiano Agropecuario, Apartado Aereo 233, Palmira, Colombia. Plant Dis. 68:994-996. Accepted for publication 1 July 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-994.

Soybean plants in southwestern Mexico had symptoms similar to those reported for machismo disease in Colombia. Phloem of diseased plants displayed positive Dienes' staining. Electron microscopy revealed many mycoplasmalike organisms in sieve elements of diseased samples from Mexico and Colombia. Numerous leafhoppers (Scaphytopius fuliginosus), known vectors of the machismo disease agent, were found in affected Mexican fields. Machismo disease of soybeans appears to be more widely distributed than previously thought.