The work was conducted in the northern area of

Costa Rica where two plots were sown: one of minimum

tillage (1.85 ha) and another of conventional tillage (2 ha).

Both tillage systems were planted with a hydraulic sower

fertilizer. The sown variety was the Brunca. The population of

bean plants evaluated during the vegetative stage was of 9.37

plants/lineal meter in minimum tillage, and of 9.55

plants/lineal meter in conventional tillage. The weed density

was larger under conventional tillage and the most prevalent

weeds were Richardia scabra, Rottboellia cochinchinensis y

Spermacoce sp. The dry weight of weeds was of 37.6 g of

weed/frame of 0.25 m2 in minimum tillage, while in the

conventional tillage it was of 46.4 g of weed/frame. The

incidence and severity of web-blight (Tanatheporus

cucumeris) in the system of minimum tillage was of 42.8%

and of 0.83, respectively, while in conventional tillage it was

of 52.2% and 1.22, respectively. In the system of minimum

tillage the yield was of 930 kg/ha, and in conventional of 676