This research on " The dose of herbicides pre and post emergent in rice ( Oryza saliva L)is watered with the system of minimum tilling in Bajo Mayo in the district of Cacatachi". It was developed in a farm that belongs to The National University of San Martín (UN.S.M) which is located in the district ofCacatachi in the province of San Martin, toan altitude of 350 o. s. l., with a rainfall of 1135 mm/year and an average temperature of 25° C. The development took from February to August in 2000. The main objectives pursued were to evaluate the effect and the efficiency of three pre emergent herbicide dose and three post emergent herbicide dose, a witness with manual weeding and with an absolute witness without weeding in the Capirona variety. Oxadiargyl (Raft), a pre emergent herbicide, was used and Carboxipirimidinil (Nominee), a post herbicide emergent, was used, too. A significant dif...