Ozone-Herbicide Interactions on Sorghum (Sorghum bicolor) and Velvetleaf (Abutilon theophrasti) Seedlings

Abstract

The potential interactive effects between the herbicides chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl] benzenesulfonamide}, PP009 {butyl 2-[4-[5-(trifluoromethyl-2-pyridinyl) oxy] phenoxy] propanoate}, and BAS 9052 OH {2-[1-(ethoxyimino)-butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexene-one} and the air pollutant ozone (O3) on the growth of sorghum [Sorghum bicolor(L.) Moench. ‘Funk G623rg’] and velvetleaf (Abutilon theophrastiMedic. # ABUTH) were examined. All three herbicides were applied postemergence either before or after a single 6-h fumigation of sorghum and velvetleaf seedlings with O3at 0, 0.1, and 0.2 ppmv. Chlorsulfuron was applied at 0, 0.06, or 0.12 kg ai/ha, while PP009 and BAS 9052 OH were applied at 0, 0.6, and 1.2 kg ai/ha. Two weeks after treatment, dry weight responses of velvetleaf seedlings revealed that PP009 interacted synergistically while chlorsulfuron and BAS 9052 OH interacted antagonistically with O3. The sequence of O3fumigation and herbicide treatment appeared to be an important factor determining the type of interactive effects of these herbicides with O3. The interactive effects of all three herbicides with O3on sorghum seedlings were additive regardless of the sequence of O3fumigation and herbicide treatment.