Abstract: A 4-yr field study was conducted to evaluate yellow nutsedge suppression in ‘Tifway’ bermudagrass. Herbicide programs included preemergence (PRE) applications of metolachlor (3.4 kg ai/ha) and postemergence (POST) applications of imazaquin (0.28 kg ai/ha) plus MSMA (2.2 kg ai/ha) or halosulfuron (0.07 kg ai/ha) plus MSMA (2.2 kg/ha). Herbicides were applied to the same plots each year. Yellow nutsedge shoot suppression and tuber numbers were determined each year. Suppression of yellow nutsedge shoots increased over the 4-yr period from <74% in 1993 to >83% by 1996 with two annual applications of imazaquin plus MSMA or halosulfuron plus MSMA. PRE metolachlor applications did not suppress shoot production in any year; nor did they enhance suppression from POST treatments. Sequential applications of halosulfuron plus MSMA and imazaquin plus MSMA increased shoot suppression by 17 to 24% at 3 mo after initial treatment (MAIT) compared to single applications. All treatments reduced tuber numbers (>60%) after 4 years compared to untreated plots.
Nomenclature: Halosulfuron, methyl 5-{[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl-aminosulfonyl}-3-chloro-1-methyl-1-H-pyrazole-4-carboxylate; imazaquin, 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid; metolachlor, [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide]; MSMA, monosodium salt of methylarsonic acid; yellow nutsedge, Cyperus esculentus L. #3 CYPES; bermudagrass, Cynodon dactylon Burtt-Davey X C. transvaalensis L. Pers. ‘Tifway’.
Abbreviations: MAIT, months after initial treatment; POST, postemergence; PRE, preemergence; WAIT, weeks after initial treatment.
