Tall fescue, a coarse, bunch-forming grass, is widely used in lawns, pastures, and erosion control. Its hardiness and adaptability make it a popular choice, but these same qualities can make it a persistent weed in unwanted areas. Effective tall fescue control requires understanding which herbicides work best, when to apply them, and how to minimize damage to desirable plants.
Understanding Tall Fescue and Why Control Matters
Tall fescue (Schedonorus arundinaceus) is a cool-season grass known for its deep roots, drought tolerance, and resistance to heavy foot traffic. While these attributes are beneficial in many situations, tall fescue can become problematic when it invades fine-textured lawns or ornamental gardens, creating an uneven and aesthetically displeasing appearance.
The aggressive nature of tall fescue allows it to outcompete other, more desirable grasses. Its clumping growth habit can disrupt the uniformity of a lawn, and its coarse texture can stand out against finer-bladed varieties. In pastures, uncontrolled tall fescue can reduce the palatability and nutritional value of the forage.
Therefore, effective tall fescue control is essential for maintaining the health, appearance, and functionality of lawns, gardens, and pastures. Selecting the right herbicide is a critical step in achieving this goal.
Glyphosate: The Go-To Non-Selective Herbicide
Glyphosate, the active ingredient in Roundup and numerous other products, is a non-selective herbicide, meaning it kills virtually any plant it comes into contact with. It’s a systemic herbicide, meaning it is absorbed by the plant’s foliage and translocated throughout the entire plant, including the roots, leading to complete kill.
Glyphosate is effective against tall fescue, but its non-selective nature necessitates careful application to avoid damaging desirable plants.
Application Techniques for Glyphosate
The key to using glyphosate effectively is precise application. Here’s how to maximize its impact:
- Spot Treatment: For isolated clumps of tall fescue in lawns or gardens, spot treatment is the preferred method. Use a handheld sprayer to carefully apply glyphosate directly to the leaves of the target grass, avoiding contact with surrounding plants. Shielding devices can further protect nearby vegetation.
- Wick Application: In areas where desirable plants are intermingled with tall fescue, a wick applicator can be used. This device applies the herbicide directly to the tall fescue leaves, minimizing the risk of overspray.
- Renovation Projects: When renovating an entire lawn or pasture infested with tall fescue, a broadcast application of glyphosate may be necessary. In this case, it’s crucial to wait the recommended amount of time after application before reseeding or replanting.
- Timing: Glyphosate is most effective when applied to actively growing tall fescue. This typically occurs in the spring and fall when temperatures are moderate and moisture is adequate. Avoid applying glyphosate during periods of drought stress or extreme heat, as this can reduce its effectiveness.
Considerations When Using Glyphosate
While glyphosate is a powerful tool for tall fescue control, several factors should be considered:
- Non-selectivity: Always protect desirable plants from accidental exposure.
- Environmental impact: Glyphosate can have environmental consequences if not used responsibly. Follow label instructions carefully and avoid applying it near waterways or sensitive areas.
- Resistance: Repeated use of glyphosate can lead to the development of herbicide-resistant weeds. Rotate herbicides with different modes of action to prevent resistance.
- Soil Activity: Glyphosate is generally considered to have little to no soil activity, meaning it doesn’t persist in the soil and affect future plantings. However, it’s always a good idea to check the product label for specific information.
Selective Herbicides: Targeting Tall Fescue While Protecting Other Grasses
While glyphosate offers a broad-spectrum solution, selective herbicides can target tall fescue without harming certain other grasses. These herbicides work by exploiting physiological differences between tall fescue and other species.
Selective herbicides are particularly useful in situations where you want to remove tall fescue from a mixed lawn without killing all the grass. It’s important to note that finding truly selective herbicides for tall fescue can be challenging, especially if the desired grass is closely related.
Examples of Selective Herbicides (Use with Caution)
While true selective control of tall fescue within a desirable cool-season lawn can be difficult, certain herbicides, used judiciously and with careful attention to label instructions, may offer some level of selective control. However, complete kill of tall fescue without some damage to desirable grasses should not be expected.
- Fenoxaprop-p-ethyl: This herbicide, found in products like Acclaim Extra, is primarily used for post-emergent control of grassy weeds. While it may suppress tall fescue, it is more effective on other annual grasses.
- Sethoxydim: This is another post-emergent grass killer. The selectivity can vary depending on the species of desirable grass you’re trying to keep.
Important Considerations:
- Label Instructions: Always read and follow the herbicide label instructions carefully. The label is the law.
- Turfgrass Species: Selectivity varies depending on the type of desirable grass. Some grasses are more tolerant than others.
- Application Rate: Using the correct application rate is crucial. Too much herbicide can damage or kill desirable grasses, while too little may not effectively control tall fescue.
- Environmental Conditions: Environmental conditions, such as temperature and humidity, can affect herbicide efficacy and selectivity.
- Spot Treatment: Spot treatment is generally the preferred method for selective herbicide application, as it allows for more precise targeting of the tall fescue.
Challenges with Selective Control
Achieving selective tall fescue control can be difficult for several reasons:
- Close Genetic Relationship: Tall fescue is closely related to many other cool-season grasses, making it difficult to find herbicides that are toxic to tall fescue but not to other desirable grasses.
- Herbicide Sensitivity: Desirable grasses can be sensitive to herbicides used to control tall fescue, leading to injury or death.
- Application Timing: The timing of herbicide application is critical. Applying the herbicide at the wrong time of year or during unfavorable weather conditions can reduce its effectiveness and increase the risk of damage to desirable grasses.
Alternative Control Methods: Beyond Herbicides
In addition to herbicides, several non-chemical methods can be used to control tall fescue. These methods may be more labor-intensive, but they can be effective in certain situations and are often preferred by those seeking to avoid herbicide use.
Manual Removal
For small infestations of tall fescue, manual removal can be an effective option. This involves digging up the entire plant, including the roots. Be sure to remove as much of the root system as possible to prevent regrowth. This method is best suited for young plants or small clumps of tall fescue.
Smothering
Smothering involves covering the tall fescue with an opaque material, such as cardboard or black plastic, to block sunlight and kill the plant. This method can be effective for larger infestations, but it can take several weeks or months to kill the tall fescue completely. It’s important to ensure that the covering is tightly sealed to prevent sunlight from reaching the plant.
Solarization
Solarization is a similar method that uses clear plastic to trap heat and kill the tall fescue. This method is most effective during the hot summer months. The plastic should be placed over the infested area and sealed tightly to the ground. The heat trapped under the plastic will kill the tall fescue and other weeds.
Cultural Practices
Certain cultural practices can help to prevent tall fescue from becoming established in the first place. These include:
- Proper Mowing: Mowing at the correct height for your desired grass species can help to promote healthy growth and prevent tall fescue from outcompeting it.
- Fertilization: Proper fertilization can also help to promote healthy grass growth and prevent tall fescue from becoming established.
- Overseeding: Overseeding with desirable grass species can help to fill in bare spots and prevent tall fescue from invading.
- Watering: Water deeply and infrequently to encourage deep root growth in desirable grasses, making them more competitive against tall fescue.
Preventing Tall Fescue Infestations
The best way to control tall fescue is to prevent it from becoming established in the first place. This can be achieved through a combination of good cultural practices and vigilant monitoring.
- Use Certified Seed: When seeding or overseeding your lawn, use certified seed that is free of weed seeds, including tall fescue.
- Maintain a Healthy Lawn: A healthy, dense lawn is less susceptible to weed infestations. Proper mowing, fertilization, watering, and aeration can help to maintain a healthy lawn.
- Control Existing Infestations: Address small infestations of tall fescue promptly before they have a chance to spread.
- Monitor Regularly: Regularly inspect your lawn for signs of tall fescue and take action as needed.
Choosing the Right Approach: A Summary
Selecting the appropriate method for controlling tall fescue depends on several factors, including the size of the infestation, the type of plants you want to protect, and your personal preferences.
- Small Infestations: Manual removal or spot treatment with glyphosate or a selective herbicide may be sufficient.
- Large Infestations: Broadcast application of glyphosate or smothering may be necessary.
- Protecting Desirable Plants: Selective herbicides, wick application of glyphosate, or non-chemical methods may be the best options.
- Environmental Concerns: Non-chemical methods or careful application of glyphosate may be preferred.
Regardless of the method you choose, it’s important to follow label instructions carefully and take precautions to protect yourself and the environment. Persistence and vigilance are key to achieving long-term tall fescue control.
What is Tall Fescue and Why is it Considered a Weed?
Tall Fescue is a cool-season perennial grass often used for lawns, pastures, and erosion control due to its durability and adaptability. However, it can become an undesirable weed when it invades areas where a different, more desirable turfgrass species is preferred, creating unsightly clumps and disrupting the uniform appearance of the lawn. Its coarse texture and rapid growth rate allow it to outcompete other grasses, making it difficult to maintain a consistent lawn surface.
In lawns comprised of finer-textured grasses like Kentucky Bluegrass or Perennial Ryegrass, Tall Fescue’s wider blades and bunch-forming growth habit stand out noticeably. This difference in texture and color disrupts the aesthetic uniformity prized by many homeowners. Furthermore, its resilience makes it difficult to eliminate without damaging the surrounding desired grasses, leading to frustration and the need for effective control methods.
What are the most effective herbicides for killing Tall Fescue?
Selective herbicides containing active ingredients like fenoxaprop-p-ethyl or fluazifop-p-butyl are effective for controlling Tall Fescue in certain situations. These herbicides target grasses and can selectively kill Tall Fescue without harming most broadleaf plants. However, they are generally less effective on mature Tall Fescue plants and may require multiple applications for complete control. Always read and follow label instructions carefully, as improper application can damage desirable grasses as well.
Non-selective herbicides containing glyphosate are also effective for killing Tall Fescue, but they will kill any plant they come into contact with. Therefore, they are best used in situations where you want to eliminate all vegetation in a specific area or for spot treatments where you can carefully apply the herbicide directly to the Tall Fescue without affecting surrounding plants. Remember to protect desirable plants by covering them or carefully applying the herbicide on a calm day to prevent drift.
How do I prepare my lawn before applying herbicide to kill Tall Fescue?
Proper lawn preparation is crucial for maximizing herbicide effectiveness and minimizing damage to desirable grasses. Start by identifying the Tall Fescue patches you want to eliminate. Avoid mowing the lawn for a few days before applying the herbicide, as this allows the Tall Fescue to have more leaf surface for absorption of the herbicide.
Water the lawn thoroughly a day or two before application, unless the herbicide label specifies otherwise. This helps ensure the Tall Fescue is actively growing, which will improve herbicide uptake and effectiveness. Avoid applying herbicide during periods of drought stress or extreme heat, as this can reduce its efficacy and increase the risk of injury to surrounding plants.
How do I apply herbicide correctly to target Tall Fescue?
Read and follow the herbicide label instructions carefully, paying close attention to the recommended application rate, timing, and safety precautions. Use a calibrated sprayer to ensure accurate and even application. Avoid overlapping spray patterns, as this can lead to over-application and potential damage to desirable plants.
When using a selective herbicide, spot treat the Tall Fescue clumps directly, avoiding overspray onto surrounding desirable grasses as much as possible. For non-selective herbicides like glyphosate, take extra care to protect nearby plants by covering them with cardboard or plastic sheeting. Apply the herbicide on a calm day to prevent drift, which can harm non-target plants.
What should I do after applying herbicide to Tall Fescue?
Avoid mowing the treated area for several days after applying herbicide to allow the herbicide to fully translocate throughout the plant. Monitor the treated Tall Fescue clumps for signs of dieback, which may take several days or weeks depending on the herbicide used and the size and maturity of the plants.
If the Tall Fescue does not show signs of decline after the recommended waiting period, a second application may be necessary, following the label instructions carefully. Once the Tall Fescue is dead, remove the dead clumps and prepare the area for reseeding or sodding with a desirable turfgrass species.
How can I prevent Tall Fescue from returning to my lawn?
Maintaining a healthy and dense lawn is the best defense against Tall Fescue invasion. Proper fertilization, watering, and mowing practices will help your desirable grasses thrive and outcompete Tall Fescue seedlings. Regular overseeding with a high-quality turfgrass mixture can also help fill in bare spots and prevent Tall Fescue from gaining a foothold.
Avoid introducing Tall Fescue seeds into your lawn by using certified weed-free grass seed and being mindful of potential sources of contamination, such as contaminated compost or improperly cleaned lawn equipment. Address any bare spots or thin areas promptly by reseeding or sodding to prevent Tall Fescue from establishing.
Are there any natural or organic methods for controlling Tall Fescue?
While natural or organic methods may not be as effective as chemical herbicides for completely eradicating Tall Fescue, they can help manage its growth and prevent it from spreading. Manual removal, such as digging up individual clumps of Tall Fescue, can be effective for small infestations, but it can be labor-intensive and requires removing the entire root system to prevent regrowth.
Smothering Tall Fescue with cardboard or black plastic can also be effective, but it can take several weeks or months to kill the plants. Another option is to use a concentrated vinegar solution (horticultural vinegar), but this is a non-selective herbicide and will kill any plant it comes into contact with, so it should be used with caution. Employing cultural practices that favor your desired grasses, like proper watering and fertilization, can also naturally suppress Tall Fescue growth over time.