Bromus diandrus Roth. control with MON 37532 in spring wheat (Triticum aestivum L.). 1. Time of application and dosage rate
MON 37532 (sulfosulfuron) is a new herbicide for the selective control of grasses and annual broadleaf weeds in wheat (Triticum aestivum L.). In this glasshouse study done in 2-litre pots filled with coarse sand, the product was evaluated for the selective control of Bromus diandrus Roth. in spring wheat. Dosage rates of MON 37532 varying between 0 and 45 g a.i ha-1, plus 0.25% of the surfactant, Agral 90, were applied at the 1-, 2-, 3- and 4-leaf stage of the weed plants. Although efficient control (> 85%) was only achieved when weeds were sprayed at the 1-leaf stage, leaf growth of all B. diandrus plants ceased within 5 days after spraying, irrespective of time of spraying. Leaf area and dry mass determinations done at 6 weeks after spraying in this study confirmed that even if sprayed at the 4-leaf stage, MON 37532 stops B. diandrus from further growth and competition with the wheat plants. Higher dosage rates may be needed when sprayed at later growth stages. Growth of the spring wheat cultivar, SST 55, used in this study was not affected by the herbicide.