Control of Green Rabbitbrush and Big Sagebrush with 2,4-D and Picloram

A mixed stand of green rabbitbrush (Chrysothamnus viscidiflorus (Hook.) Nutt. var. puberulus Jepson) and big sagebrush (Artemisia tridentata Nutt.) was sprayed at different dates for 3 years with potassium salt of 4-amino-3,5,6-trichloropicolinic acid (picloram) at ¼, ½, and 1 1b/A, propylene glycol butyl ether esters of 2,4-dichlorophenoxyacetic acid (2,4-D) at 1, 2, and 3 1b/A, and a mixture of triisopropanolamine salts of picloram plus 2,4-D at ¼ plus 1 and ½ plus 2 1b/A. Picloram at ½ and 1 1b/A controlled rabbitbrush but not sagebrush. Poor rabbitbrush control and fair to good sagebrush control resulted from 2,4-D. The mixture of picloram and 2,4-D controlled rabbitbrush well but only partially controlled sagebrush. Forage release from brush control was negligible the first 2 years after spraying. During the third and subsequent years, production of crested wheatgrass (Agropyron desertorum (Fisch.) Schult.) was greatly increased.