Wheat Tolerance to TCA for Green Foxtail Control

Abstract

Seven cultivars of spring wheat (Triticum aestivum L.) and one hybrid (Triticale hexaploid Lart. ‘Rosner’) were evaluated in seven field experiments and one greenhouse test for tolerance to the postemergence application of the sodium salt of trichloroacetic acid (TCA) for the control of green foxtail (Setaria viridis (L.) Beauv.). The control of green foxtail and broadleaf weeds was also studied. Of the seven cultivars, ‘Pitic 62’ and ‘Stewart’ were most susceptible to injury from TCA. All other cultivars were tolerant to 0.56 kg/ha. ‘Selkirk’ appeared to be most resistant. With ‘Manitou’ 0.56 kg/ha of TCA gave about 50% control of green foxtail. Higher rates permitted increased growth of broadleaf weeds as a result of reduced competition from injured wheat and green foxtail. Control of all weeds was improved by 10 to 30% when TCA was applied with one of the phenoxy herbicides. Satisfactory crop tolerance and good weed control was achieved with 0.56 kg/ha TCA and 0.56 kg/ha of the amine salt of (2,4-dichlorophenoxy)acetic acid (2,4-D).