Nutsedge & Kyllinga: Herbicide Timing Built on Biology

The Impact of Sedges on Turfgrass Quality

Few weeds are as persistent or problematic in managed turfgrass as yellow nutsedge (Cyperus esculentus), purple nutsedge (Cyperus rotundus), and kyllinga species (Kyllinga spp.).  Whether on golf courses or residential lawns, these sedges can weaken turf uniformity, outcompete desirable grass species, and challenge even the most diligent weed management programs.

Unlike most grassy weeds, nutsedges and kyllinga thrive in moist, compacted soils where other turf species struggle. Their bright green, glossy foliage and rapid growth rate stand out sharply against finer-bladed turfgrasses, creating an uneven appearance. Over time, dense colonies can form, thinning the turf canopy and increasing susceptibility to additional weed pressure.

Kyllinga, particularly false green kyllinga (Kyllinga gracillima), has become increasingly problematic in cool- and warm-season turf due to its aggressive growth, ability to spread through rhizomes, and tolerance to mowing. Yellow nutsedge, on the other hand, propagates through underground tubers, known as nutlets, which can remain dormant and viable in the soil for years—making long-term control especially difficult.

Why Are These Weeds So Tough to Control?

Nutsedges and kyllinga are not true grasses—they’re sedges. As such, they differ physiologically and anatomically, which limits the effectiveness of many conventional post-emergent herbicides. Nutsedge’s ability to produce multiple generations of tubers during the growing season adds to its persistence, while kyllinga’s creeping rhizomes make mechanical removal nearly impossible without further spread.

Moreover, many turf herbicides struggle to penetrate the waxy cuticle and erect leaf structure of sedges, leading to inconsistent control. That’s why cultural practices and strategic timing play such a crucial role in successful sedge management.

Cultural Practices to Reduce Sedge Pressure

Cultural practices form the foundation of any integrated sedge management program. Here are some best practices:

• Improve drainage: Sedges flourish in wet or poorly drained soils. Correcting drainage issues and avoiding overwatering can significantly reduce sedge infestations.
• Alleviate compaction: Aerification promotes better soil structure and root development for turf while creating less favorable conditions for sedge growth.
• Mow appropriately: Regular mowing at the correct height for your turf species can limit the energy sedges can devote to reproduction.
• Maintain dense turf: A healthy, competitive turf canopy shades out sedge seedlings and limits their establishment.

Developmental Biology: The Key to Control

Understanding the developmental biology of nutsedges is vital—especially when it comes to timing herbicide applications. The ideal window to control nutsedges is when the soil temperature at a 2" depth has reached 65°F for 7 consecutive days.

Adapted from Seasonal Development of Yellow and Purple Nutsedges

Jordan-Molero, J.E. and E.W. Stoller, 1978.

This is a critical biological sweet spot:

• At this temperature, leaf development is at its peak, allowing for maximum foliar herbicide uptake.
• Yet, the weed has not yet begun tuberization, the process by which it forms new underground nutlets. Once tuberization begins, control becomes significantly more difficult, and the weed's ability to rebound increases.

By targeting sedges at this vulnerable stage—before underground energy storage structures are formed—you dramatically improve your chances for lasting control. This timing is also highly effective for false green kyllinga control.

Recommended Solutions: Expel and Smokeshow Herbicides

When it comes to sedge control, choosing the right herbicide based on your turf type and target species is essential. Two highly effective tools in the fight against nutsedges, kyllinga, and other sedge species are Expel and Smokeshow herbicides.

Expel is a go-to choice for both cool- and warm-season turfgrasses. It provides reliable control of yellow nutsedge and false green kyllinga, with excellent turf safety and systemic activity that targets the weed at its most vulnerable stage.

• Labeled for use in a wide range of turf types, including Kentucky bluegrass, tall fescue, perennial ryegrass, bermudagrass, zoysiagrass, and more.
• Delivers strong post-emergent activity with proven efficacy against sedge species.
• Ideal for use when soil temperatures reach 65°F at 2” depth for 7 consecutive days—the optimal timing for herbicidal uptake.

Smokeshow is a powerful option specifically designed for warm-season turf, delivering broad-spectrum sedge control, including yellow nutsedge, false green kyllinga, and purple nutsedge. Its enhanced formulation provides fast knockdown with residual activity, making it an excellent choice for high-pressure areas.

• Recommended for use in bermudagrass, centipedegrass, and zoysiagrass.
• Particularly effective on purple nutsedge, which is often more difficult to control than yellow nutsedge.
• Combines multiple modes of action for enhanced control and resistance management.

Final Thoughts

Effective sedge management is not just about the "what"—it’s about the "when." By aligning herbicide applications with the biology of the weed, turf managers can significantly improve control outcomes. Cultural practices and a thorough understanding of sedge development go hand-in-hand with smart herbicide selection.

Don’t wait until these invaders have taken hold. Monitor soil temperatures early in the season, and when that 65°F threshold is met, strike with Expel or Smokeshow herbicides to stop sedges before they spread.