Summary 1. Six years of work with post emergence applications of propanil to potatoes have proven that it is an efective herbicide. 2. To control weed populations propanil should be used at 0.75 to 1 pound of active ingredient per acre when the broad-leaved weeds are from two to four inches high. Applications at 2 pounds and over per acre reduced yields in several tests. 3. Applications of the herbicide should be made with a suitable sprayer, using a sufficient pressure and volume of spray mixture to ensure adequate coverage of weeds growing within and below the canopy formed by the potato vines. 4. Propanil should not be used in conjunction with the insecticides Sevin, Thimet, or malathion. 5. The insecticide Thiodan and the fungicide maneb have been proven to be compatible with propanil.