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.

A two-choice type bioassay has been used to screen extracts from a number of plants of the sagebrush community for their antifeeding properties against the Colorado potato beetle, Leptinotarsa decemlineata Say. The extracts of Artemisia tridentata, Purshia tridentata and Chrysothamnus nauseosus have been fractionated for their antifeeding constituents. Known constituents of these plants (deacetalmatricarin, coumarins, cucurbitacins, polyphenols, polyacetylenes, and essential oils) were also screened. The results indicate that several chemical classes of compounds are responsible for antifeeding activity in each plant. Water soluble substances present in the waste marc after steam distillation of peppermint oil were highly active, too.