ABSTRACT
Much of the ground water quality concern, related to the use of herbicides on golfcourses, is based on extrapolation from agricultural situations rather than data developed from studies conducted in field turfgrass situations. To address this data gap, a two-year field project evaluating the behavior and mobility of the commonly used preemergent herbicides, benfluralin, trifluralin, bensulide, oxadiazon, pendimethalin, and DCPA with its two metabolites was conducted at OARDC/The Ohio State University, Wooster, Ohio, in 1988–89. Plots were located on a site with thatch (WT) and one with no thatch (NT) to further clarify the impact of thatch on herbicide behavior. Treatments were applied in April and samples of thatch and four zones of soil (0–2.5, 2.5–5, 7.5–10 and 22.5–25 cm) were collected throughout the year and analyzed for residue dissipation. Residues of pendimethalin, benfluralin, and trifluralin in the 22.5–25 cm zone were below the limit of determination. No detectable oxadiazon residues were found in this zone at the WT site in 1988 but on two occasions, residues of 0.01 and 0.02 kg/ha were found in 1989. At the NT site, residues in this zone on one occasion were 0.02 kg/ha in 1988 and none in 1989. Residues of bensulide in the same zone ranged not detectable (ND)-0.02 kg/ha in both locations. The DCPA residues in the 22.5–25 cm zone ranged ND-0.10 kg/ha (WT), ND-0.27 kg/ha (NT) in 6141988, and ND-0.02 kg/ha (WT), ND-0.04 kg/ha (NT) in 1989. The residues of SDS 1449, the less stable of two dacthal metabolites, were very low but higher in 1988 than in 1989 in both locations. The SDS 954 residues in 22.5–25 cm zone ranged ND-0.1 kg/ha (WT), and ND-0.16 kg/ha (NT) in 1988, and ND-0.26 kg/ha (WT), and ND-0.27 kg/ha (NT) in 1989.
Some amount of all herbicides applied carried over into the spring of the year following application but oxadiazon and bensulide were the most persistent.
