Imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} sorption and mobility were studied in five Alabama soils ranging from sandy loam to clay. Techniques included thinlayer soil chromatography, batch equilibrium, and soil solution recovery. Imazaquin was mobile in all soils with Rfvalues of 0.8 to 0.9. Sorption based on batch equilibrium was minimal with Kdvalues ranging from 0.001 to 0.21. The soil solution recovery technique was used to evaluate imazaquin sorption in each soil as influenced by imazaquin concentration, wetting and drying, and pH. As herbicide concentration added to the soils was increased from 0.1 to 10 mg/kg, the amount of14C-imazaquin in soil solution increased. Temporarily drying each soil to 25 or 50% of field capacity resulted in maximum sorption of imazaquin. Lowering the pH enhanced sorption in all soils such that the amount of imazaquin in solution ranged from 38 (low pH) to 100% (high pH). Soil sorption appeared to be governed by the pH-dependent charge surfaces from aluminum and iron oxyhydroxides (specifically hematite and gibbsite) and kaolinite.

Transformation of soybean [Glycine max (L.) Merr.] with a gene encoding a glyphosate‐tolerance 5‐enolpyruvylshikimate‐3‐phosphate synthase enzyme from Agrobacterium sp. strain CP4 resulted in the development of glyphosate‐tolerant line 40‐3‐2. Glyphosate (N‐phosphonomethyl glycine) is the active ingredient of Roundup herbicide. Line 40‐3‐2 was yield tested at 17 locations in 1992,23 locations in 1993, and 18 locations in 1994. At those locations, broadcast applications of glyphosate at various rates were made over 40‐3‐2 or its derivatives from early vegetative growth to pod fill. No significant yield reduction was observed as a result of the glyphosate treatment at any of the locations. Development of glyphosate‐tolerant soybean promises to provide the farmer with access to a new weed control system that should result in lower production costs and reliable weed control under a wide range of conditions.

Annual bluegrass is commonly controlled by acetolactate synthase (ALS)-inhibiting herbicides in managed turfgrass. An annual bluegrass population with suspected resistance to ALS-inhibiting herbicides was collected from Grand National Golf Course in Opelika, AL (GN population). Subsequent testing confirmed resistance of the GN population to foramsulfuron, trifloxysulfuron, bispyribac-sodium (bispyribac), and imazaquin when compared to a susceptible population collected locally at Auburn University (AU population). Sequencing of the ALS gene revealed a point mutation resulting in an amino acid substitution at Trp574. Cloning of the ALS gene surrounding the Trp574 region yielded two distinct ALS gene sequences: one producing Trp574 and one producing Leu574. Trp574 to Leu has been previously correlated with resistance to ALS-inhibiting herbicides. Both AU and GN gene sequences contained other similar silent and missense mutations. This research confirms resistance of annual bluegrass to ALS-inhibiting herbicides with Trp574 to Leu amino acid substitution being the most likely mode of resistance based on past literature.

Integrated weed management (IWM) became an accepted, and frequently used, term by weed scientists in the early 1970's. It has been argued by some that IWM is simply new terminology for a system that was previously called “weed control”. In any event, the acceptance of the “management concept” has assured the grower that chemicals for weed control are merely a component part of a total system for managing weeds in crops (9, 65).