Compounds of Formulae I, II, III and IV:
wherein
R¹ is alkyl;
R² is H, alkyl, alkenyl or alkynyl;
R³ and R⁴ are independently H, optionally substituted alkyl, alkenyl or alkynyl;
X is selected from various organic groups; and
Q is selected from various aryl and heterocyclic groups;
exhibit broad spectrum preemergent and postemergent herbicidal activity.