Tillage and pendimethalin either alone or in combination were compared for weed management in two potato cultivars. The best weed management program consisted of a combination of pendimethalin and tillage. Pendimethalin alone did not adequately control weeds. Multiple cultivations gave better control than pendimethalin alone but not as good as pendimethalin and cultivation combined. The net returns using tillage, pendimethalin, and tillage plus pendimethalin for weed control averaged –$86, –$208, and $ 143/ha, respectively. Independent of their effect on weeds, cultivation had a significant negative effect and pendimethalin a significant positive effect on potato yields. Each cultivation reduced yields by 1.7% and pendimethalin increased yields by 4%. The cultivar ‘Red Pontiac’ was a better competitor with weeds than ‘Red Norland’.
