Published online by Cambridge University Press: 12 June 2017
Bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] was evaluated for Canada thistle [Cirsium arvense (L.) Scop. # CIRAR] control and birdsfoot trefoil (Lotus corniculatus L. ‘Norcen’) tolerance. Bentazon applied in split applications controlled more Canada thistle than a single application of equal rate in both greenhouse and field studies. Bentazon applied four times reduced the level of total nonstructural carbohydrates (TNC) in the roots of both greenhouse- and field-grown Canada thistle and increased birdsfoot trefoil injury more than bentazon applied in a single application of equal rate. All bentazon treatments caused unacceptable injury when birdsfoot trefoil was grown for seed.