What Herbicide Kills Dallisgrass – Your Ultimate Guide To Eradicating

Are you battling persistent clumps of dallisgrass in your otherwise pristine lawn? You’re not alone. This aggressive, warm-season perennial weed is a common frustration for homeowners and landscapers alike, known for its rapid growth and unsightly appearance. It can quickly spread, outcompeting desirable turfgrass and making your lawn look patchy and unkempt.

Identifying dallisgrass is the first step, but the real challenge lies in finding an effective solution. Many common weed killers simply won’t touch it, leaving you feeling defeated. That’s why understanding exactly what herbicide kills dallisgrass is crucial for reclaiming your green space.

In this comprehensive guide, we’ll dive deep into identifying this stubborn weed, explore the most effective herbicide options available, detail proper application techniques, and outline essential cultural practices for long-term control. Get ready to arm yourself with the knowledge to achieve a beautifully uniform, dallisgrass-free lawn.

Understanding Dallisgrass: The Enemy Identified

Dallisgrass (Paspalum dilatatum) is a warm-season perennial grass native to South America. It thrives in various soil types and climates, making it a widespread problem across many regions. Recognizing it early is key to successful management.

Key Identification Features

• Growth Habit: It grows in unsightly clumps, often larger and coarser than surrounding turf.
• Leaf Blades: The leaves are wide (up to ½ inch), light green, and typically have a prominent midrib. They are usually folded in the bud.
• Seed Heads: A distinctive feature is its long, slender seed stalk with 2-7 spike-like branches (racemes) arranged alternately along the upper portion. Seeds are fuzzy and often appear in summer and fall.
• Rhizomes: Dallisgrass spreads by short, thick rhizomes (underground stems) as well as by seed, making it particularly difficult to eradicate.

Unlike crabgrass, which is an annual that dies with the first frost, dallisgrass is a perennial. This means its roots survive winter, allowing it to return year after year, often stronger than before.

The Challenge of Dallisgrass Control

Controlling dallisgrass is notoriously difficult due to several factors. Its vigorous growth habit and ability to regenerate from rhizomes make it resilient. Many common broadleaf weed killers are ineffective against grassy weeds like dallisgrass.

Why Dallisgrass Is So Stubborn

• Deep Root System: Its extensive root system allows it to withstand drought and makes manual removal challenging.
• Prolific Seeder: Each plant produces thousands of viable seeds, ensuring its return if not properly managed.
• Perennial Nature: Unlike annual weeds, it doesn’t die off completely in winter, regrowing from its crown and rhizomes each spring.
• Selective Control Difficulty: Finding an herbicide that kills dallisgrass without harming desirable turfgrass is a balancing act.

Understanding these challenges helps set realistic expectations and emphasizes the need for a multi-pronged approach.

What Herbicide Kills Dallisgrass? Effective Solutions

When tackling dallisgrass, you’ll primarily consider two types of herbicides: pre-emergents and post-emergents. Each plays a vital role in a comprehensive control strategy. Knowing what herbicide kills dallisgrass effectively means choosing the right product for the right situation.

Pre-Emergent Herbicides: Prevention Is Key

Pre-emergent herbicides create a chemical barrier in the soil that prevents germinating seeds from establishing. They do not kill existing weeds.

• Active Ingredients: Look for products containing prodiamine (e.g., Barricade), dithiopyr (e.g., Dimension), or pendimethalin.
• How They Work: These chemicals inhibit cell division in germinating seeds, stopping them before they emerge.
• Timing: Apply pre-emergents in early spring before soil temperatures consistently reach 55-60°F, which is when dallisgrass seeds begin to germinate. A fall application can also help control late-season germination.
• Considerations: Do not apply pre-emergents if you plan to overseed your lawn, as they will prevent desirable grass seeds from germinating too.

Post-Emergent Herbicides: Targeting Established Weeds

Post-emergent herbicides are applied directly to existing dallisgrass plants. These are the chemicals you’ll use when you see the weed actively growing.

• Quinclorac: The Go-To Option
  • Effectiveness: Quinclorac is widely considered one of the most effective selective post-emergent herbicides for dallisgrass in many turfgrass types, including fescue, perennial ryegrass, Kentucky bluegrass, and some warm-season grasses like Bermuda.
  • How it Works: It’s a systemic herbicide, meaning it’s absorbed by the leaves and transported throughout the plant, including the roots and rhizomes, leading to complete kill.
  • Brand Names: You’ll find quinclorac in products like Drive XLR8, Image Kills Dallisgrass, and various crabgrass killers that also list dallisgrass on their label. Always check the label for specific weeds controlled.
  • Application: Often requires a non-ionic surfactant to improve absorption. Multiple applications, 2-3 weeks apart, may be necessary for complete eradication due to dallisgrass’s robust nature.
• MSMA (Monosodium Methylarsonate): Restricted Use
  • Effectiveness: Historically, MSMA was very effective for dallisgrass control in warm-season grasses like Bermuda, zoysia, and centipede.
  • Restrictions: Due to environmental and health concerns, MSMA’s use is now heavily restricted in the United States. It is typically only available for use on golf courses, sod farms, and similar commercial applications, not for residential lawns. Always check local regulations.
• Glyphosate: Non-Selective Caution
  • Effectiveness: Glyphosate (e.g., Roundup) is a highly effective non-selective herbicide that kills almost any plant it touches, including dallisgrass and your desirable turf.
  • Use Cases: It’s best reserved for spot treatment of isolated dallisgrass clumps in landscape beds, cracks in pavement, or for complete lawn renovation where you intend to reseed or resod the entire area.
  • Caution: Exercise extreme care to avoid drift onto desirable plants. Use a spray shield or paintbrush for precise application.
• Other Selective Options (Warm-Season Grasses):
  • For warm-season lawns like Bermuda or zoysia, some specialized herbicides containing active ingredients like sulfosulfuron (e.g., Certainty) or foramsulfuron (e.g., Revolver) can provide dallisgrass control. These are often professional-grade products and require careful application.
  • Fenoxaprop-p-ethyl (e.g., Acclaim Extra) is another option for certain turf types, particularly fescue, for grassy weed control.

Selective vs. Non-Selective: Making the Right Choice

Understanding the difference is crucial. Selective herbicides are designed to kill specific weeds without harming desirable plants (e.g., quinclorac in a fescue lawn). Non-selective herbicides kill nearly all plant material they contact (e.g., glyphosate).

For dallisgrass in your lawn, you almost always want a selective post-emergent. If a clump is too large or in a non-turf area, a targeted glyphosate application might be considered, but with utmost care.

Applying Herbicides Safely and Effectively

Proper application is just as important as choosing the right product. Incorrect use can lead to ineffective control, damage to your lawn, or environmental harm.

Read the Label: Your Most Important Tool

Every herbicide product has a detailed label that is a legal document. It provides critical information on:

• Target weeds and compatible turfgrass types.
• Application rates and mixing instructions.
• Safety precautions and Personal Protective Equipment (PPE).
• Environmental hazards and restricted entry intervals (REI).
• Optimal application timing and conditions.

Never apply an herbicide without thoroughly reading and understanding its label. This is non-negotiable for safety and efficacy.

Timing Is Everything: When to Apply

For post-emergent herbicides like quinclorac, application is most effective when dallisgrass is actively growing. This typically means late spring through early fall, when temperatures are consistently between 65°F and 85°F.

• Avoid applying when temperatures are too hot (above 90°F), as this can stress your desirable turf.
• Apply when rain is not expected for at least 24 hours to allow the herbicide to be absorbed.
• Multiple applications (often 2-3, spaced 2-3 weeks apart) are usually required to kill dallisgrass completely due to its perennial nature.

Proper Application Techniques

• Calibration: Ensure your sprayer is calibrated to deliver the correct amount of product per square foot. Too little won’t work; too much can damage your lawn.
• Uniform Coverage: Apply the herbicide evenly over the target area. Spot treatments should be precise.
• Wind Conditions: Avoid spraying on windy days to prevent drift onto non-target plants, especially with non-selective products.
• Adjuvants: Many post-emergent herbicides, especially quinclorac, recommend or require a non-ionic surfactant (NIS) to help the herbicide stick to and penetrate the waxy leaf surface of dallisgrass.

Cultural Practices: Your Long-Term Defense Against Dallisgrass

Herbicides are powerful tools, but they are just one part of a comprehensive dallisgrass management plan. Healthy turf is the best defense against weeds.

Mowing Height: Starving the Weed

Mow your lawn at the highest recommended height for your turfgrass type (typically 3-4 inches). Taller grass shades the soil, reducing dallisgrass seed germination and outcompeting existing weeds for sunlight and nutrients.

Ensure your mower blades are sharp for a clean cut that promotes healthy grass growth and reduces disease entry points.

Proper Watering: Deep and Infrequent

Water your lawn deeply and infrequently (e.g., 1 inch of water once or twice a week). This encourages deep root growth in desirable turf, making it more resilient to stress and better able to outcompete shallow-rooted weeds.

Frequent, shallow watering can favor dallisgrass and other weeds.

Fertilization Strategies: Promoting Healthy Turf

A well-fertilized lawn is a strong lawn. Conduct a soil test to determine your lawn’s specific nutrient needs (NPK ratios). Fertilize according to recommendations, usually in spring and fall for cool-season grasses, or late spring/early summer and fall for warm-season grasses.

Healthy, dense turf leaves less room for dallisgrass to establish and thrive.

Aeration and Dethatching: Improving Soil Health

Aeration (removing small plugs of soil) improves air, water, and nutrient penetration to the root zone. Dethatching (removing excess thatch) also helps. These practices promote a healthier lawn, reducing compaction that can favor weeds.

Perform these practices when your desirable turf is actively growing and can recover quickly.

Mulching in Landscape Beds

In non-turf areas like flower beds or around trees, a 2-4 inch layer of organic mulch (e.g., shredded bark, wood chips) can effectively suppress dallisgrass. Mulch blocks sunlight, preventing seed germination and making it easier to pull any weeds that do emerge.

Integrated Pest Management (IPM) for Sustainable Dallisgrass Control

The most effective and sustainable approach to dallisgrass control is through Integrated Pest Management (IPM). This involves combining chemical, cultural, and mechanical methods to minimize weed pressure while promoting a healthy ecosystem.

Key Principles of IPM for Dallisgrass

• Identification: Correctly identify the weed.
• Monitoring: Regularly scout your lawn for new dallisgrass growth.
• Prevention: Use pre-emergent herbicides and strong cultural practices.
• Intervention: Apply post-emergent herbicides strategically when necessary.
• Evaluation: Assess the effectiveness of your methods and adjust as needed.

By integrating these strategies, you reduce reliance on herbicides, build a more resilient lawn, and achieve better long-term results.

Seasonal Considerations for Dallisgrass Management

Your approach to dallisgrass control will vary depending on the season.

• Spring: Apply pre-emergent herbicides early to prevent germination. Begin post-emergent treatments on emerging clumps once temperatures are consistently warm.
• Summer: Continue post-emergent treatments as dallisgrass is actively growing. Maintain proper mowing and watering to support turf health.
• Fall: A second round of post-emergent herbicide can target late-season growth. Consider a fall pre-emergent application to catch any seeds that might germinate before winter. Overseed desirable grass if needed.
• Winter: Dallisgrass goes dormant, so herbicide application is ineffective. Focus on dormant season lawn care and planning for spring.

Safety First: Protecting Yourself, Pets, and the Environment

Working with herbicides requires careful attention to safety. Always prioritize protection.

• Personal Protective Equipment (PPE): Wear long sleeves, long pants, closed-toe shoes, gloves, and eye protection. A respirator may be necessary for some products or in enclosed spaces.
• Wind and Drift: Never spray on windy days. Be mindful of herbicide drift, which can damage non-target plants, contaminate water sources, and pose risks to people and pets.
• Pet and Child Safety: Keep pets and children off treated areas until the spray has dried completely, or for the duration specified on the product label (Restricted Entry Interval – REI).
• Storage: Store herbicides in their original containers, in a cool, dry, secure location, out of reach of children and pets.
• Disposal: Dispose of empty containers and unused product according to label instructions and local regulations. Never pour chemicals down drains or into storm sewers.

Your safety and the health of your environment are paramount when applying any chemical product.

Frequently Asked Questions About Dallisgrass Control

Is Dallisgrass Hard to Kill?

Yes, dallisgrass is notoriously difficult to kill due to its deep root system, prolific seed production, and perennial nature. It often requires multiple applications of specific post-emergent herbicides combined with strong cultural practices.

Can I Just Pull Dallisgrass by Hand?

Manual removal is possible for small, isolated clumps, especially in landscape beds. However, it’s labor-intensive, and you must ensure you remove the entire root and rhizome system, or it will regrow. For larger infestations, it’s not practical or effective.

Will Vinegar Kill Dallisgrass?

Horticultural vinegar (acetic acid) can burn back the top growth of dallisgrass, but it typically does not kill the deep roots or rhizomes. Therefore, it’s usually not an effective long-term solution for eradication and will likely regrow.

When Is the Best Time to Apply Dallisgrass Killer?

For post-emergent herbicides, the best time is when dallisgrass is actively growing, typically from late spring through early fall, when temperatures are consistently between 65°F and 85°F. Pre-emergent herbicides should be applied in early spring before seeds germinate.

How Long Does It Take for Dallisgrass to Die After Herbicide Application?

The time it takes for dallisgrass to die varies depending on the herbicide, weather conditions, and plant health. You might see yellowing or browning within a few days to a week, but complete death can take 2-3 weeks. Multiple applications are often needed for full control.

Conclusion: Reclaim Your Lawn From Dallisgrass

Dallisgrass may be a formidable foe, but with the right knowledge and tools, you can win the battle. Understanding what herbicide kills dallisgrass effectively, coupled with diligent application and robust cultural practices, is your pathway to success. Remember, consistency and patience are key.

By implementing a comprehensive IPM strategy – combining selective post-emergent herbicides like quinclorac with preventive pre-emergents and excellent lawn care – you can significantly reduce and eventually eliminate this stubborn weed. Reclaim your beautiful, uniform lawn and enjoy the fruits of your labor!

Taylor Galla Founder of Garden Aider

• Mechanical engineer
• Gardening since 2010
• Univ. of Nevada, Reno

From the author's notebook

Taylor pairs an engineer's eye with years of hands-on work in soil, lawns and outdoor machinery. He tests ideas in his own garden, keeps tractors and mowers running himself, and speaks to local horticulture groups. Every Garden Aider guide is written to be practical, accurate and safe to follow.

“To bring life alive, you just need to mix some love with the compost, bedding, and gardening machines.”

Published Jul 14, 2026