Sprays of 2.2 kg ae/ha of 2,4-D [(2,4-dichlorophenoxy)acetic acid] and 0.5, 1.1, or 2.2 kg ae/ha of clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) were applied at three Utah sites. The 2,4-D and 1.1 or 2.2 kg/ha of clopyralid effectively controlled mountain big sagebrush (Artemisia tridentata Nutt. # ARTTR ssp. vaseyana). Applications of 2.2 kg/ha of 2,4-D resulted in 84% mortality of antelope bitterbrush [Purshia tridentata (Pursh.) DC] and killed 96% of the Saskatoon serviceberry (Amelanchier alnifolia Nutt.). Clopyralid applications of 2.2 kg/ha killed only 5% of the antelope bitterbrush and 6% of the Saskatoon serviceberry. Thus, clopyralid is an effective alternative to 2,4-D for control of mountain big sagebrush when the desirable shrubs antelope bitterbrush and/or Saskatoon serviceberry are present.

Foliar-applied herbicides were evaluated in one greenhouse and five field studies for control of silver beardgrass (Andropogon saccharoides Swartz. # ANOSA). In the greenhouse, terbutryn [N-(1,1-dimethylethyl)-N′-ethyl-6-(methylthio)-1,3,5-triazine-2,4-diamine] and the isopropylamine salt of glyphosate [N-(phosphonomethyl) glycine] at 3.4 kg ai/ha each consistently controlled silver beardgrass from 7 to 75 days after treatment. Field studies were conducted to investigate silver beardgrass control as influenced by herbicides and timing of herbicide application. Generally, glyphosate at 1.1 and 1.7 kg/ha satisfactorily controlled silver beardgrass with little or no permanent damage to the existing bermudagrass [Cynodon dactylon (L.) Pers. # CYNDA] turf. Decreasing water carrier volume from 374 to 187 L/ha did not affect phytoactivity of terbutryn at 3.4 kg/ha or glyphosate at 0.4, 0.6, 0.8, or 1.1 kg/ha.

Preplant incorporation of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] at 3.6 kg ai/ha, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] at 2.2 kg ai/ha, and tank mixtures of imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} with either alachlor at 0.14 + 2.2 kg ai/ha or metolachlor at 0.14 + 1.1 kg ai/ha controlled >90% red rice (Oryza sativa L. # ORYSA) in soybeans [Glycine max (L.) Merr.]. Also, FMC-57020 [2-(2-chlorophenyl)methyl-4,4-dimethyl-3-isoxazolidinone] at 1.7 kg ai/ha applied preplant incorporated controlled > 80% of the red rice. DPX-Y6202 {2-[4-[(6-chloro-2-quinoxalinyl)oxy]-phenoxy]-propionic acid, ethyl ester} was the best and most consistent postemergence herbicide treatment for red rice control when applied once at 0.28 kg ai/ha or sequentially at 0.14 kg ai/ha each time. Haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl]oxy] phenoxy] propanoic acid} applied at 0.16 kg ai/ha followed by another application at 0.14 kg ai/ha gave excellent red rice control in 2 of 3 years. Soybeans were uninjured by the herbicide treatments and yield was higher from treated than untreated soybeans.