Bean IPM

Legume ipmPIPE Diagnostic Series

Machismo or Phytoplasma Disease Group


Machismo or Phytoplasma organisms transmitted by leafhoppers such as Scaphytopius fuliginosus. Symptoms of this disease group may include witches’ broom, virescence (flower petals turn light to dark green), phyllody (unopened, distorted floral structures), elongation of stems, and distorted pods with few seeds which may germinate in healthy appearing pods.

Factors favoring
  • Presence of previously infested crop debris
  • Lack of crop rotation
  • Poor sanitation of previous legume and weed debris
  • Contaminated seed
  • Susceptible varieties
  • Moderate to high moisture conditions favor slugs
  • Infection at V2 – R2 results in plant death, and/or reduced pod set, poor seed fill, and yield loss
Phytoplasma stunted leaves
Phytoplasma stunted leaves
Distorted leaves
Additional Resources

H. F. Schwartz, Colorado State University and S. K. Mohan, University of Idaho

Photo credits

Courtesy of G. E. Galvez (CIAT – APS Bean Compendium), S. K. Mohan and H. F. Schwartz