Quackgrass is a persistent and aggressive perennial grass weed that can be very difficult to control in lawns. Once quackgrass gets established, it spreads rapidly through its rhizomes and can take over large areas of your lawn quickly. The key to controlling quackgrass is using a combination of cultural practices and herbicide applications. Here are some effective strategies for getting rid of quackgrass in your lawn.
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What is quackgrass?
Quackgrass (Elymus repens) is a cool-season perennial grass that is considered a weed in lawns and gardens. It is native to Europe but has spread widely across North America. Quackgrass gets its name from its hollow stems that were used to make duck calls. Other common names for quackgrass include couchgrass, quitch grass, dog grass, and witchgrass.
Quackgrass spreads aggressively through rhizomes, which are underground stems that can grow up to 6 feet long. Nodes along these rhizomes can produce new shoots and roots. Even small rhizome fragments left in the soil can re-sprout into new plants. Quackgrass also spreads readily by seed, producing up to 800 seeds per plant which can remain viable in the soil for up to 4 years.
Once established, quackgrass forms dense clumps and mats that crowd out desirable lawn grasses. It is distinguished from typical lawn grasses by its broader, lighter green leaves, clasping auricles, and spreading rhizomes. Quackgrass is quicker to green up in spring than associated cool-season lawn grasses.
Why is quackgrass a problem in lawns?
There are several reasons why quackgrass can become a problematic weed in lawns:
- It’s extremely competitive – Quackgrass grows rapidly and produces a large root system, allowing it to outcompete surrounding lawn grasses for water, nutrients, light and space.
- Forms thick clumps – Individual quackgrass plants grow together in clumps or patches that can quickly dominate areas of the lawn.
- Spreads aggressively – Its spreading rhizomes allow quackgrass to invade new areas of the lawn each year, increasing its coverage.
- Difficult to control – Quackgrass has a high tolerance for many herbicides. Its extensive root system enables it to recover quickly from mowing, digging or other control attempts.
- Detracts from lawn appearance – The lighter color and different texture of quackgrass stands out from surrounding lawn grasses, creating an uneven, patchy look.
- Reduces lawn function – Dense quackgrass clumps restrict movement for sports and other lawn activities and access for mowing.
If quackgrass is not controlled, it will continue spreading and may eventually overtake the entire lawn. It is very difficult to eradicate once established, so taking action at the first signs of quackgrass invasion is advised.
Cultural control of quackgrass
Cultural practices that promote healthy, dense turfgrass can help reduce quackgrass invasion and growth. Cultural control options include:
- Proper mowing – Maintain lawn at the highest recommended height for the turfgrass type. This increases competition against quackgrass. Do not mow quackgrass too short, as this can stimulate growth.
- Irrigation – Water infrequently but deeply to encourage deeper root growth of desired turfgrasses. Quackgrass prefers frequent, light irrigation.
- Fertilization – Apply moderate levels of nitrogen fertilizer to improve vigor of desired turfgrasses. Avoid excessive nitrogen which favors quackgrass growth.
- Dethatching – Removal of thatch improves turfgrass vigor and reduces quackgrass habitat.
- Overseeding – Slit seeding helps desirable turfgrasses fill in bare areas and thin spots vulnerable to quackgrass invasion.
- Aeration – Core aeration relieves soil compaction and encourages deeper rooting of desired turf.
While cultural practices help discourage quackgrass, they alone are usually insufficient for controlling existing heavy infestations. Combining cultural and chemical controls is most effective.
Herbicide control options
Several effective herbicide options are available for quackgrass control in lawns. Timing, choice of product, and proper application technique are important factors for achieving control. Herbicide options include:
Pre-emergents
Pre-emergent herbicides like prodiamine, dithiopyr and pendimethalin provide some suppression of quackgrass by inhibiting new shoot growth from rhizomes. However, they do not control existing plants. Apply pre-emergents in early spring before soil temperatures reach 55°F.
Glyphosate (non-selective)
Glyphosate is a systemic, non-selective herbicide that controls most types of vegetation. When applied to actively growing quackgrass, it translocates down through the plant’s rhizomes to kill the entire plant. Glyphosate is available is several products such as Roundup and KleenUp.
The nonselective activity of glyphosate requires careful application only on quackgrass plants to avoid lawn damage. Spot treatment of individual quackgrass clumps or early spring applications before lawn green-up are options. Glyphosate will take 1-2 weeks for complete plant death.
Selective herbicides for lawn use
Several selective post-emergent herbicides provide effective quackgrass control in lawns when applied correctly:
- Mesotrione – Found in products like Tenacity and Scotts Starter Fertilizer with Weed Preventer. Provides fair quackgrass suppression. Requires multiple applications.
- Fenoxaprop – The active ingredient in products like Acclaim Extra. Controls crabgrass and quackgrass when applied at higher rates.
- Flazasulfuron – Found in Katana turf herbicide. Labeled for quackgrass and nimblewill control in cool-season turfgrasses.
- Rimsulfuron – The active ingredient in Tomasek TM Quackgrass Killer. Provides selective quackgrass control in cool-season turfgrasses.
- Sulfosulfuron – Sold as Certainty turf herbicide. Often combined with other active ingredients like metsulfuron-methyl.
For best results, apply selective herbicides when quackgrass is actively growing in spring or fall. Adjuvants like methylated seed oils improve uptake. Avoid mowing for several days before and after application. It may take 2-3 treatments for full control. Carefully follow label directions for all herbicides.
Manual and mechanical control
For light quackgrass infestations, manual and mechanical techniques like hand-pulling, hoeing, tilling or sod removal can be effective. However, these methods rarely provide complete control due to the extensive rhizome system. For manual and mechanical control:
- Hand pull small clumps when soil is moist and attempt to remove all roots and rhizomes.
- Hoe or till repeatedly to chop up quackgrass roots and rhizomes.
- Remove sod and at least 3 inches of soil in heavily infested patches before re-sodding.
- Solarization using clear plastic sheeting can help weaken quackgrass by raising soil temperatures.
Combine manual/mechanical techniques with herbicide treatments or re-sodding for best results. Persistence is required, as quackgrass can re-grow from tiny rhizome fragments left behind.
Best practices for quackgrass control
Here is a summary of key practices that are part of an integrated strategy to get rid of quackgrass from your lawn:
- Promote healthy, dense turf with proper mowing, fertilization, irrigation, dethatching and overseeding.
- Scout regularly for new quackgrass patches and start control efforts promptly.
- Apply pre-emergent herbicides like prodiamine in spring to inhibit growth.
- Use glyphosate for spot treatment of small areas when lawn is dormant.
- Apply selective post-emergent herbicides for larger areas when quackgrass is actively growing.
- Combine chemical controls with manual removal methods like digging and hoeing.
- Re-sod areas that cannot be brought under control using other methods.
- Reseed bare areas after control efforts to establish desirable turfgrasses.
- Do not allow quackgrass to go to seed to prevent further spread.
- Continue monitoring and follow-up applications in subsequent seasons.
While difficult to eliminate, a comprehensive strategy and persistence can provide effective quackgrass control and reclaim your lawn.
Quackgrass control products
Here are some recommended products for quackgrass control, with application notes:
| Product | Active Ingredient(s) | Notes |
|---|---|---|
| Tenacity | Mesotrione | Fair suppression; multiple apps needed |
| Roundup | Glyphosate | Non-selective; avoid lawn contact |
| Acclaim Extra | Fenoxaprop | Selective; use higher rates |
| Certainty | Sulfosulfuron | Selective; combine with other herbicides |
| Katana | Flazasulfuron | Selective; cool-season grasses only |
Conclusion
Quackgrass can quickly become a stubborn weed problem in lawns, but a variety of effective control options exist. The key is using cultural practices to promote dense, competitive turfgrasses and integrating targeted herbicide applications. Products like glyphosate, Acclaim Extra, Katana and Certainty provide selective quackgrass control when applied carefully and repeatedly. Combining chemical and manual techniques offers the best defense against this aggressive perennial weed. With persistence and diligence in following these control strategies, you can rid your lawn of troublesome quackgrass.