Summary.Studies on the physiological effects of dalapon inCynodon dactylon(L.) Pers. were carried out. Field and glasshouse experiments showed that dalapon is freely translocated in the aerial organs and from these to the rhizomes. No transformation of the herbicide was detected during 72 h following application. In rhizomes as well as in stolons, dalapon caused growth inhibition and necrosis of buds while root growth was apparently not affected. This differential susceptibility was confirmed by culturing node explants in nutrient solution containing dalapon. Although dalapon killed aerial organs, most rhizomes were capable of recovery even when a high dose was applied. These results are discussed.Effets physiologiqius du dalapon surCynodon dactylon (L.)Pers.