Studies show that once a suppressive effect has been established, a green manure treatment for a single season is sufficient to either maintain or to re-establish the control of Verticillium wilt of potato. Verticillium wilt, caused by Verticillium dahliae Kleb., was controlled on the first years of Russet Burbank potato cropping following 2-3 successive years of green manure treatments. Following this control, yields were increased with the first year of potato cropping, but were reduced during the second consecutive year of cropping with potato. In the second year of continuous cropping with Russet Burbank, total yields were reduced by 10% and U.S. #1 tubers by 40%, and these yield reductions were accompanied by increased soil populations of V. dahliae by >5-fold. Yet, with a single season of an earlier-used green manure treatment (e.g. Austrian winter pea, sudangrass, Dwarf Essex rape, Bridger rape, oats, rye, or sweet corn), Verticillium wilt was again controlled and yields of Russet Burbank were increased to higher levels or to levels that were equivalent to those initially observed following either 2 or 3 successive seasons of green manure treatment. Green manures also demonstrated significant effects on microbial activities, which were inversely related to the incidence of Verticillium wilt. More specific effects on microbial activity and soilborne ecology were shown with increased populations of Fusarium spp. Verticillium wilt was negatively correlated with infections of potato feeder roots and stem-ends of potato tubers by F. equiseti. Exemplifying the effect of a green manure on fungal ecology, sudangrass treatments were shown to have lasting effects on Fusarium avenaceum populations with quantitative changes that extended 5 years beyond the time of soil incorporation with sudangrass.Resumen Los estudios demuestran que una vez que se ha establecido el efecto supresivo, es suficiente un tratamiento con abono verde por un ciclo de cultivo ya sea para mantener o re-establecer el control del marchitamiento por Verticillium en papa. El marchitamiento por verticillium, causado por Verticillium dahliae Kleb, fue controlado en los primeros años del cultivo de papa Russet Burbank siguiendo dos o tres años sucesivos de tratamientos con abono verde. Siguiendo este control, se aumentaron los rendimientos en el primer año del cultivo de la papa, pero se reducía durante el segundo año consecutivo de cultivo con papa. En el segundo año continuo del cultivo con Russet Burbank , se redujo el rendimiento total en un 10% y los tubérculos U.S. # 1 en 40%, y estas reducciones se acompañaron por el aumento en las poblaciones de V. dahliae en más de cinco veces. Pero con un tratamiento temprano de abono verde en un ciclo (por ejemplo, chícharo Australiano de invierno, pasto sudán, colza enana Essex, colza Bridger, avena, centeno, o maíz dulce), se controlaba nuevamente el marchitamiento por Verticillium y se aumentaban los rendimientos de Russet Burbank a niveles más altos o equivalentes a aquellos observados inicialmente sig...