Since 1967, many diseases have been associated with mycoplasma- like microorganisms (MLM), especially when symptoms have been characterized by general plant chlorosis, stunting, excessive proliferation of branches (witches' broom), bud proliferation and disorders of floral organs (phyllody and virescence). Many causal agents are transmitted naturally by leafhoppers to various hosts. Various MLM are known to infect beans, such as legume little-leaf transmitted by Orosius argentatus, witches'-broom, phyllody and virescence. In Colombia, a MLM was detected and is known as machismo or amachamiento, transmitted by Scaphytopius fuliginosus. The symptoms of infection generaly become apparent during flowering and pod development. Control measures include adequate crop rotation and elimination of weed hosts, and the use of insecticides. The symptoms and damage caused by the organisms are illustrated in color. (CIAT)Desde 1967, muchas enfermedades se han asociado con los microorganismos semejantes a micoplasmas (MSM) especialmente cuando los sintomas se han caracterizado por una clorosis general de la planta, raquitismo, proliferacion excesiva de ramas (superbrotamiento) y desordenes en los organos florales (filodia y virescencia). Los saltahojas transmiten en forma natural numerosos agentes causales a diversos hospedantes. Se conocen varios MSM que infectan el frijol como la hoja pequena de las leguminosas transmitida por Orosius argentatus, el superbrotamiento y filodia y virescencia. En Colombia se registro un MSM conocido como machismo o amachamiento transmitido por Scaphytopius fuliginosus. Los sintomas de infeccion generalmente se manifiestan durante el periodo de floracion y formacion de vainas. Las medidas de control incluyen una adecuada rotacion de cultivos y eliminacion de las malezas hospedantes, y el uso de insecticidas. Se ilustran a color los sintomas y danos causados por los organismos. (RA
