Municipalities are considering alternatives to traditional herbicides for suppressing weeds and vegetation in areas frequented by the public. Two field experiments were conducted to test the efficacy of alternative nonselective herbicides: one in Corvallis, OR, on a mixed lawn of perennial ryegrass, annual bluegrass, and broadleaf weeds, and another in Las Cruces, NM, on a predominantly bermudagrass lawn with broadleaf weeds. The experimental objective was to quantify and compare the effects of repeated applications of 10 nonselective herbicides to terminate a lawn with mixed vegetation. Applications were made every 2 wk for four applications starting on April 15, 2022, in Corvallis and on May 26, 2022, in Las Cruces. Data collected included the percent green cover over time calculated using an area under the percent green cover progress curve (AUPGCPC), the percent green cover at the conclusion of the experiment, and the changes in monocot and dicot densities over the course of the experiment. All treatments resulted in a lower AUPGCPC compared to water only, except for mint oil + sodium lauryl sulfate + potassium sorbate. The only treatments with average percent green cover <50% were ammoniated soap of fatty acids + maleic hydrazide (47% green cover) in Corvallis and pelargonic acid (38%) in Las Cruces, suggesting that more applications would be needed to terminate the lawn under similar circumstances. At the conclusion of the experiment, the water-only plots averaged 90% and 93% green cover in Corvallis and Las Cruces, respectively. The changes in monocot and dicot densities over the course of the experiment indicated that some of the products tested may be more sensitive to dicots, or, in some cases, monocots, suggesting a potential for future selective herbicide research in certain locations and climates.

Field studies were conducted at Charleston, SC to evaluate the effects of six chemical treatments on bahiagrass and the potential of these treatments to reduce mowing operations. Sulfometuron, maleic hydrazide, and imazethapyr plus imazapyr, in decreasing order of effectiveness, were the most consistent treatments evaluated during the 2-yr study. Sulfometuron reduced bahiagrass vegetative height (23%) for 6 to 8 WAT and suppressed 87 to 92% of seedheads without adversely affecting turf quality. All treatments temporarily discolored turf; however, effects were not objectionable for medium- to low-quality turf settings. Sulfometuron, maleic hydrazide, and imazethapyr plus imazapyr controlled growth and maintained acceptable turf quality for an average of 9, 9, and 8 wk, respectively; thereby reducing mowing operations by an average 29%. Mefluidide plus fluazifop-P, mefluidide plus sulfometuron, and chlorosulfuron were the least effective and/or consistent treatments evaluated.