Herbicidal Control of Greasewood (Sarcobatus vermiculatus) and Salt Rabbitbrush (Chrysothamnus nauseosus ssp. consimilis)

The control of greasewood [Sarcobatus vermiculatus (Hook.) Torr.] and salt rabbitbrush [Chrysothamnus nauseosus ssp. consimilis (Greene) Hall and Clem.] was investigated with application of 2,4-D [(2,4-dichlorophenoxy)acetic acid] and a mixture of 2,4-D and picloram (4-amino-3,5,6-trichloropicolinic acid). The herbicides were applied at 2-week intervals from May 1 to August 1. Greasewood had accelerated shoot growth and was most susceptible to application of 2,4-D during June. Accelerated shoot growth and maximum susceptibility to 2,4-D of salt rabbitbrush began in June and extended into July. Mortality of greasewood and salt rabbitbrush from 2,4-D at 2.2 kg/ha applied at optimum dates averaged 72 and 87%, respectively. The picloram/2,4-D mixture was more effective for greasewood control than 2,4-D alone in 1 yr at very early and late application dates on a xeric site and only at the last date of application on a mesic site. Reapplication of 2,4-D at 2.2 and 3.3 kg/ha in June to partially controlled stands gave excellent control of both greasewood and rabbitbrush.