NC State Warns: Herbicide Runoff Damages Golf Course Turf

Research Highlights Turf Maintenance Challenges

A recent study, published in *Weed Technology* in 2025 by Pritchard and colleagues, has shed light on an often-overlooked challenge in golf course maintenance: the downhill movement of herbicides.

While superintendents meticulously apply treatments to specific areas, the research indicates that rain or irrigation can carry these chemicals beyond their intended zones, potentially harming adjacent turf that was meant to remain untreated. This phenomenon underscores the complex considerations involved in managing diverse grass types across varied topography on a golf course.

The trials for this study were conducted at NC State University during 2023 and 2024, focusing on two specific herbicides to assess their lateral movement.

Observed Distances of Turf Damage

The study specifically investigated the lateral movement of tetflupyrolimet, a herbicide currently under consideration for future turfgrass weed control, and pronamide, which was included due to its known downhill mobility. Researchers observed that damage associated with tetflupyrolimet extended approximately 3.6 feet downslope from the treated area.

For pronamide, the farthest observed injury to perennial ryegrass, used as an indicator, ranged between five and six feet, depending on the specific conditions. These measurements reveal how even a short distance can separate a treated patch from sensitive, untreated turf, posing a challenge for precise application and protection of adjacent areas.

Experimental Conditions and Limitations

The trials at NC State University were conducted on a sloped area with sandy loam soil, under two distinct soil-moisture conditions. Perennial ryegrass was strategically planted to clearly track any herbicide-induced injury in areas below the application zone.

The researchers noted that these distances reflect the specific experimental setup, which included removing the above-ground bermudagrass canopy and planting ryegrass solely for the experiment.

They caution that these figures should not be interpreted as recommended buffer distances for product use, as real-world golf course environments with different soil types, ground cover, or water flow patterns could yield varying results. The study, funded by FMC, also disclosed an author's affiliation with the company.

Implications for Asian Golf Course Management

For golf course superintendents across Asia, these findings present critical considerations, particularly given the region's diverse climates and topographies. Many Asian courses feature undulating terrain, a mix of grass species in close proximity, and regular heavy rainfall or extensive irrigation, which can exacerbate herbicide runoff.

Managers in areas prone to monsoon seasons or with steeply sloped fairways and greens must account for potential lateral movement when planning turf treatments. This research suggests a need to review current application protocols, possibly adjusting spray patterns or considering enhanced buffer zones to protect sensitive turf areas or adjacent natural habitats.

Understanding local soil conditions and water drainage patterns will be key to mitigating unintended herbicide damage and maintaining course quality.