A new benzoxazolinone, 5-chloro-6-methoxy-2-benzoxazolinone (Cl-MBOA) caused growth inhibition of roots and shoots of oat (Avena sativa), timothy (Phleum pratense), crabgrass (Digitaria sanguinalis), ryegrass (Lolium multiflorum), cockscomb (Amaranthus caudatus), cress (Lepidium sativum) and lettuce (Lactuca sativa); increasing the dose of Cl-MBOA increased inhibition. The concentrations for 40% inhibition of root growth were 0.12, 0.14, ...