Trials were conducted on bio-control of the common smut disease caused by Ustilago maydis (DC.) Cda on teosinte (Zea mexicana) and maize (Zea mays). Soybean, maize, sunflower and vegetable oils were used as foliar spray at 30 cc/L of water under artificial inoculation under greenhouse and field conditions. Oil foliar applications wear done one day before, on the same day and one day after plant inoculation by the smut pathogen, or before and after. The results on teosinte showed the efficacy of maize and soybean oils without significant differences. The overall results showed that the ranked order of treatments revealed the effectiveness of maize oil followed by the fungicides, vegetable oils (in one experiment), and soybean oil in a descending order in greenhouse. Repeated greenhouse test indicated significant differences between both treatments of soybean and maize oils, and the check (not-treated). Foliage oil spray after plant inoculation ranked first for oils followed by simultaneous spray and plant inoculation for soybean and sunflower without significant differences. Results on maize were similar to teosinte. Both results showed the efficacy of the used oils to control the smut disease on both crops.