Management of herbicide resistant weeds in Latin America: The case of propanil-resistant Echinochloa colona in rice

The most important case of herbicide resistance in Latin America is that of junglerice, Echinochloa colona, resistant to propanil. Resistant populations have been found in all Central American countries and Colombia. Resistance is associated with an increased activity of the enzyme aryl acylamidase in the resistant biotypes which enables them to metabolize propanil at a much higher rate than the susceptible biotypes. Integrated management tactics can help in controlling resistant populations and preventing resistance evolution. In-crop modification of conventional weed control practices, including the use of alternative herbicides and specific synergists, allow economical management of resistant populations.