Q & A WITH DR. GRADY MILLER

Is there anything new for ryegrass removal on overseeded fields?

Every year, when weather conditions become warm enough to stress ryegrass, I begin receiving questions about transitioning overseeded fields back to bermudagrass. I still visit sites that do not chemically transition fields, but instead rely on Mother Nature to provide sufficiently high temperatures to weaken the ryegrass while concurrently fertilizing the bermudagrass to increase competition.

This approach can work well in warmer climates that warm early in spring and remain warm. However, in the more northern regions of the transition zone, newer perennial ryegrass cultivars can often survive through spring and into summer, with a high percentage regrowing in the fall once temperatures moderate. Increased competition from ryegrass in mid- to late spring can reduce bermudagrass stands, so a more aggressive approach may be warranted to optimize long-term turfgrass health.

A routine management practice is the use of selective herbicides as a transition aid. Several products are labeled and marketed for reducing perennial ryegrass with no adverse effects on bermudagrass color or overall turfgrass quality. These products include Certainty, Katana, Kerb, Manor / MSM, Monument, Revolver and TranXit. All of these products, except for Kerb, belong to the sulfonylurea family of herbicides. Kerb is by far the slowest-acting product in this group, with Manor / MSM being the next slowest.

You specifically asked,“ what is new?” A newer product, not belonging to the sulfonylurea family, has been labeled for ryegrass transition. This product is Sapphire( trade name penoxsulam). Although Sapphire is in a different herbicide family, it still functions by inhibiting the acetolactate synthase( ALS) enzyme, similar to the sulfonylureas.

While transition products have improved over the last 20 years, they are still not foolproof. Depending on geographic location and event timing, most managers apply these prod- ucts between mid-April( e. g., Florida) and mid-May( upper transition zone). Repeat applications may be necessary to achieve complete control. Sulfonylurea herbicides are rate- and temperature-sensitive; therefore, higher labeled rates and warmer temperatures generally result in faster perennial ryegrass removal. Always review the label before using any pesticide.

For those seeking greater assurance of transition without chemical use, fraise mowing has been identified as a cultural practice that can aid ryegrass removal in spring or summer. Research suggests that fraise mowing to a depth of 0.5 to 0.6 inches in late spring or summer is the optimum depth and timing. Shallower fraise mowing( approximately 0.3 inches) has been slower and less effective at complete ryegrass removal compared to deeper depths. Managers should note that deeper fraise mowing can delay bermudagrass recovery; therefore, later removal dates should be used to take advantage of improved bermudagrass growing conditions. If the field will experience continued use during the transition period, fraise mowing may not be a suitable option.

In summary, there are several new tools— both chemical and cultural— available today, along with many older, proven methods. The choice of tools will depend on location, budget, desired speed of removal, and the level of field use during the transition period.

Grady Miller, Ph. D. Professor and Extension Turf Specialist North Carolina State University

Questions? Send them to Grady Miller at North Carolina State University, Box 7620, Raleigh, NC 27695 or e-mail grady _ miller @ ncsu. edu

46 SportsField Management | May 2026 sportsfieldmanagementonline. com