Response of Bedding Plants and Weeds to Herbicides

Abstract

Preemergence and postemergence herbicides were evaluated for summer weed control and for phytotoxicity of 6 commonly used annual bedding plant species. Dacthal (dimethyl 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate), Enide (N,N-dimethyl-a-phenyl benzene acetamide), Devrinol (N,N-diethyl-2-(1-naphthalenyloxy) propanamide), Surflan (4-(dipropylamino)-3,5-dinitro-benzenesulfonamide), Ronstar (3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-1(1,1-dimethylethy1)-1,3,4-oxadiazol-2-(3H)-one), Kerb (3,5-dichloro(N-l, 1-dimethyl-2-propynyl)benzamide), and Treflan (2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl) benzenamine) at 3.3 kg/ha (3.0 lb/A) applied as preemergence treatments and Poast (2-[1-(ethoxyimino)-butyl]-5[2-ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one) and Fusilade (+)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid) applied as postemergence treatments effectively controlled large crabgrass [Digitaria sanguinalis (L.) Scop.] throughout a two-month period. Effective prostrate pigweed (Amaranthus blitoides S. Wats.) control was achieved by use of Dacthal at 14.0 kg/ha (12.5 lb/A), Surflan at 1.1 kg/ha (1.0 lb/A) and Ronstar at 3.3 kg/ha (3.0 lb/A) and postemergence application of Escort (2-[[[[(4-methoxy-6-methyl-1 ,3,5-triazin-2-yl)amino]carbonyl]-amino] sulfonyl]benzoic acid) at 0.07 kg/ha (0.06 lb/A). SC 1084 (methyl 3-hydroxy-4-[4-[[5-(trifluoromethyl)-2-pyridinyl]-oxy]-phenoxy]-pentanoate at 0.13 kg/ha (0.12 lb/A) was ineffective in controlling either weed. Plant vigor of salvia was reduced by Dacthal at 11.2 kg/ha (12.5 lb/A), while vigor of ageratum and geranium was reduced by Enide at 4.4 kg/ha (4.0 lb/A). The vigor of geranium and salvia was lower than untreated plants when treated with Devrinol at 3.3 kg/ha (3.0 lb/A). The vigor of petunia, marigold, and salvia was also lower than untreated plants when treated with Ronstar at 3.3 kg/ha (3.0 lb/A) while vigor of geranium, salvia, marigold, and zinnia was lower when treated with Surflan at 2.2 kg/ha (2.0 lb/A). Kerb at 1.6 kg/ha (1.5 lb/A) reduced the vigor of geranium, petunia, and salvia when compared with untreated plants. Poast at 0.28 kg/ha (0.25 lb/A) did not injure any of the annuals while marigold and zinnia were injured with Fusilade at 0.2 kg/ha (0.18 lb/A). Escort at 0.07 kg/ha (0.06 lb/A) and Oust (2-[[[[(4,6-dimethyl-2-pyrimidinyl)amino]-carbonyl]amino]sulfonyl]benzoic acid) at 0.07 kg/ha (0.06 lb/A) applied as postemergence applications severely injured all annuals.