Trial was carried out in March 2015 at dedo district, South West Ethiopia to test host resistance and reduced fungicide application for management of late blight. In this experiment four improved and one local potato varieties were used. RCBD with seven replications were established. A recommended rate of Ridomil-gold WP 65% fungicide was applied while susceptible local variety developed the first blight symptom. GLM procedures were followed to analyze yield, yield components, disease incidence and severity. LSD (P<0.05) values were used to separate treatments mean. Number of tubers per plant, weight of tubers per plant, total weight of tubers per plot and weight of marketable tubers per plot were show significant difference (P<0.01) among treatments. The highest number of tuber per plant was scored by variety Jalene (13.6). Bubu and local varieties scored the least (10.07 and 10.47) respectively. Variety belete gave the highest weight of tubers per plant (1.37 kg) where as local variety gave the least (0.7 kg). Local variety scored lower total weight of tubers per plant and marketable tubers per plot (31.53 and 26.03 kg). Variety belete scores the highest total weight of tubers per plant and marketable tubers per plot (61.77 and 58.22 kg). Local potato variety also gave the highest unmarketable tubers weight per plot. The result indicated that there were a significant difference (P<0.05) among treatments on late blight incidence and severity. Local variety showed highest late blight incidence and severity as compare to variety belete. The experiment result suggested that application of Ridomil-gold WP 65% once on variety belete results in significant reduction on late blight progress, with a corresponding increased tubers yield.