south american leaf blight (salb), caused by microcyclus ulei (anamorph fusicladium macrosporum), is an endemic major disease of the rubber tree (hevea brasiliensis) in america. as well as in other crop systems, its management on rubber plantations relies on plant genetic resistance availability, among other means. fx 3864 is a rubber tree clone widely planted in colombia due to its production capability and disease resistance. during 2010 salb symptoms developed in commercial crops at the meta region of colombia. crop traps located nearby the plantations showed mean disease severity levels of 5.78%. once the causal organism was microscopically confirmed as responsible for the diseased tissue, their origin was characterized by molecular means using 4 microsatellites specific to the rubber tree. the procedure confirmed that fx 3864 was the clone of origin of the leaf tissue. salb occurring over fx 3864 implies the need to redirect crop disease management measures to be followed on the new development areas of rubber cultivation, warning growers about potential hazards of disease incidence.