Herbicides applied April 30, May 10, or October 14 gave best control of musk thistle (Carduus nutansL.). The most effective herbicide at all dates and rates was 4-amino-3,5,6-trichloropicolinic acid (picloram). Two lb/A of 2-methoxy-3,6-dichlorobenzoic acid (dicamba) also was effective at all spring dates. Two lb/A of 2,4-dichlorophenoxyacetic acid (2,4-D) resulted in excellent control of musk thistle when applied May 10 or October 14.More musk thistle seedlings became established in nongrazed, cool season grass pastures than in nongrazed, mixed warm season grass pastures. Greater germination was attributed to the reserve moisture and accumulation of litter which served as an excellent germination medium. However, only one musk thistle plant remained in the nongrazed pastures 1 year after seeding. The remainder of the seedlings and young rosettes found in the protected areas in 1965 had succumbed to the heavy competition by 1966.
