Differential Response of Ditchbank Grasses to Herbicides

Abstract

Herbicides were evaluated for selectivity between three tall coarse grasses and three short fine grasses. Reed canarygrass (Phalaris arundinaceaL.), quackgrass [Agropyron repens(L.) Beauv.], and smooth brome (Bromus inermisLeyss) were consistently more susceptible to amitrole-NH4CN (3-amino-s-triazole-ammonium thiocyanate) than three desirable short grasses, Kentucky bluegrass (Poa pratensisL.), creeping red fescue (Festuca rubraL.), and redtop (Agrostis albaL.). Reed canarygrass and redtop were more susceptible to dalapon (2,2-dichloropropionic acid) than creeping red fescue. Amitrole-NH4CN and dalapon combinations were more toxic to reed canarygrass, smooth brome, and redtop than creeping red fescue. Pyriclor (2,3,5-trichloro-4-pyridinol) was quite toxic to all grasses with Kentucky bluegrass showing the most tolerance. When TCA (trichloroacetic acid) was combined with amitrole-NH4CN results were similar to the dalapon combination but overall toxicity was reduced.