The herbicidal activity of Diuron against the test plants was determined following the procedure described previously. In this procedure gradient concentration below the solubility limit was prepared and added to several plastic pots containing 10 seeds of the test plant (Jew’s mallow Corchorus olitorius). The pots were then transferred to the growth chamber for 2 weeks and irrigated as necessary. After 2 weeks % growth inhibition of the tested plant was calculated according to growth inhibition equation