Chemical control of ragwort. Upper left—Ragwort is eradicated with hormone weedkillers if the first application is made when the flower stalk bolts from the rosette, the stage illustrated. Upper right-An area which was infested with ragwort and which has had the initial application with water-based salts and amines (left) compared with an untreated area (right). Lower left—If plants are sprayed at the seed-head stage, especially with water-based salts and amines, results are disappointing. Best results are obtained with oil-based esters. Lower right-Stem twisting and leaf kill of mature plants as a result of being sprayed with an ester preparation. Such late treatment often results in the formation of viable seed and strong regrowths.

New Zealand Journal of Agriculture, Volume 84, Issue 4, 15 April 1952, Page 275

Chemical control of ragwort. Upper left— Ragwort is eradicated with hormone weedkillers if the first application is made when the flower stalk bolts from the rosette, the stage illustrated. Upper right-An area which was infested with ragwort and which has had the initial application with water-based salts and amines (left) compared with an untreated area (right). Lower left— If plants are sprayed at the seed-head stage, especially with water-based salts and amines, results are disappointing. Best results are obtained with oil-based esters. Lower right-Stem twisting and leaf kill of mature plants as a result of being sprayed with an ester preparation. Such late treatment often results in the formation of viable seed and strong regrowths.