However, several treatments are necessary for effective control. Biology, Ecology and Control in Florida by Colvin et al . Application of herbicids to kill cogongrass along roadsides does not present a problem of off-target drift. However, in wooded areas, care must be used to avoid herbicides which harm trees. The dead leaves of cogongrass remain upright and do not decay easily.
Dead leaves prevent herbicides from being effectively absorbed.
For effective control, herbicides should be applied to green leaves. Living leaves allow the herbicide to be transported to rhizomes. When a herbicide reaches the rhizomes, better control results. The timing for application of herbicides is critical. Late fall is an excellent time to apply herbicides because plants are then sending carbohydrates into the roots and rhizomes for storage.