Published online by Cambridge University Press: 12 June 2017
Imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} was evaluated in the field for weed control in flue-cured tobacco (Nicotiana tabacum L.) during 1983 and 1984. The 75 DG formulation of imazaquin was used at 0.28 and 0.42 kg ai/ha. Methods of application were: preplant incorporated, over the top immediately after transplanting, postbed incorporated, and early postemergence. Imazaquin controlled 90%, or better, of common lambsquarters (Chenopodium album L. # CHEAL), common ragweed (Ambrosia artemisiifolia L. # AMBEL), redroot pigweed (Amaranthus retroflexus L. # AMARE), spiny amaranth (Amaranthus spinosus L. # AMASP), ivyleaf morningglory [Ipomoea hederacea (L.) Jacq. # IPOHE], sicklepod (Cassia obtusifolia L. # CASOB), and prickly sida (Sida spinosa L. # SIDSP) with all application methods except early postemergence. It controlled 80 to 89% of large crabgrass (Digitaria sanguinalis L. # DIGSA) by the soil-applied methods. Postemergence applications of imazaquin controlled common ragweed, pigweed spp., ivyleaf morningglory, prickly sida, and sicklepod. Imazaquin was less effective postemergence on lambsquarters and large crabgrass. Tobacco tolerated use of imazaquin by all methods of application except preplant incorporation.