Response of Kleingrass and Buffelgrass to Herbicides1

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AbstractKleingrass and buffelgrass are sometimes difficult to establish in the field from seeding because of poor seedling vigor and severe competition from weeds. Greenhouse studies were conducted to evaluate the tolerance of kleingrass (Panicum coloratum L. ‘Selection 75’) and buffelgrass (Cenchrus ciliaris L. ‘Nueces’) seedlings to nine herbicides applied pre and postemergence at rates of 0, 0.28, 0.56, 1.12, and 2.24 kg/ha. Herbicides investigated were atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine], ametryn [2‐(ethylamino)‐4‐(isopropylamino)‐6‐(methylthio)‐s‐triarine], prometryn [2,4‐bis(isopropylamino)‐6‐(methylthio)‐s‐triazine], and propazine [2‐chloro‐4,6‐bis(isopropylamino)‐s‐triazine]; linuron [3‐(3,4‐dichlorophenyl)‐l‐methoxy‐l‐methylurea], pendimethalin [N‐(lethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine], alachlor [2‐chloro‐2',6'‐diethyl‐N‐(methoxymethyl)acetanilide], metolachlor [2‐chloro‐N(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐l‐methylethyl)acetamide], and propachlor [2‐chloro‐N‐isopropylacetanilide].Kleingrass and buffelgrass were grown in a 1:1:1 Houston black clay (Udic Pellustert): sand: peat moss mixture in small pots. Five to 10 plants were typically grown in each pot with five replications (pots) per treatment. All herbicides were sprayed in water at a spray volume of 93.5 L/ha. Herbicide injury counts were made by visually estimating percent desiccation and/or dead plants per pot 14 days after treatment.Kleingrass seedlings were tolerant to preemergence sprays of propazine up to and including 0.56 kg/ha. All other herbicides and rates applied preemergence were phytotoxic to emerging kleingrass. At the early postemergence stage, kleingrass tolerated rates up to and including 2.24, 0.56 and 0.28 kg/ha of propazine, propachlor and metolachlor, respectively, but did not tolerate other herbicides included in the study. Response of buffelgrass to pre and postemergence applications of propazine was similar to kleingrass. Buffelgrass, however, tolerated early postemergence sprays of propachlor and atrazine at 0.28 and 0.56 kg/ha; pendimethalin and alachlor at 1.12 kg/ha each; and metolachlor at 2.24 kg/ha. Propazine was the only herbicide that showed promise for both preemergence and postemergence applications in kleingrass and buffelgrass.