Response of Common Goldenweed (<i>Isocoma coronopifolia</i>) and Buffelgrass (<i>Cenchrus ciliaris</i>) to Fire and Soil-Applied Herbicides

Abstract

Controlled burning during winter reduced densities of common goldenweed [ Isocoma coronopifolia (Gray) Greene] by 33 to 44% and suppressed canopy cover and height of surviving common goldenweeds for 2 yr. Applied to an unburned infestation, 2,4-D [(2,4-dichlorophenoxy) acetic acid] or dicamba (3,6-dichloro- o -anisic acid) granules only partially controlled common goldenweed at rates of 2 kg/ha or less. Tebuthiuron { N -[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl] -N,N′ -dimethylurea} or picloram (4-amino-3,5,6-trichloropicolinic acid) pellets provided excellent control of common goldenweed if applied at 2 kg/ha during March and at 1 kg/ha if applied after burning in February. The burning pretreatment appeared to synergistically enhance effectiveness of herbicides applied at relatively low rates. Increases in standing crop of buffelgrass ( Cenchrus ciliaris L.) following burning were usually small and temporary, but effective herbicide treatments and burn-herbicide combinations increased buffelgrass standing crop by as much as three-fold.