Key Takeaways

• Goosegrass is a challenging weed to control because it is highly adaptable, is a prolific seed producer and has a long and unpredictable period of seedling emergence.
  
  
• Herbicide resistance is a major issue and goosegrass populations have been reported with resistance to several herbicide modes of action. Additionally, changing weather patterns are impacting preemergence herbicide timing.
  
  
• Healthy turf is the best defense against goosegrass. Implementing cultural practices that reduce compaction, minimize bare soil, and promote a dense, healthy turf canopy will reduce goosegrass germination and development. 
  
  
• Oxadiazon is the foundation of many preemergence programs and use for goosegrass control in cool-season turf has increased due to resistance issues with other herbicides. However, there are important new label changes to consider and thoughtful application strategies are needed.
  
  
• Superintendents are having success controlling goosegrass by combining multiple pre or postemergence active ingredients in a single application, incorporating new herbicides, using class B PGRs, and employing other innovative chemical control methods alongside conventional control strategies.
   

Ecotypes

Once goosegrass plants have emerged and begin tillering, identification is fairly easy due to its prostrate appearance, characteristic silver color at the base, tightly folded vernation and wide, flat stems. Similar to annual bluegrass, goosegrass’ ability to adapt to a wide range of management practices and growing environments on a golf course has given rise to different ecotypes. In shaded environments, plants grow more upright to compete with turfgrasses. In fairways, tees and collars, plants adapt to close mowing heights by growing stems nearly horizontally and can produce viable seed at fairway height and lower. A study of extremely dwarf ecotypes collected from putting greens in Texas and Florida suggests the plants can adapt to new environments and pass those traits along to future generations (Patel et al., 2023).

Preemergence Herbicide Timing and Duration of Control Considerations

The fact that goosegrass germination begins three to four weeks later in the spring than crabgrass and continues all summer is a concern for golf course superintendents and is problematic considering traditional preemergence herbicide timing. In Tennessee for example, emergence typically begins in April and continues through at least August, long after any preemergence products applied for crabgrass and other weeds in late winter or early spring would still be effective. This highlights the need for a dedicated control program specifically targeting goosegrass. Changing weather patterns are complicating matters further, shifting the emergence window to earlier in the spring and later in the summer in many areas.
 

Herbicide Resistance Complicates Control

Herbicide resistance is a major issue that impacts the control of many weeds on golf courses, including goosegrass. Resistance develops from repeated use of the same herbicide or mode of action. As susceptible goosegrass is controlled, resistant plants spread, shifting weed populations from susceptible to resistant over time.

Goosegrass populations have been reported in turfgrass and agricultural settings with resistance to multiple herbicide modes of action including the following Herbicide Resistance Action Committee (HRAC) classification groups:

• Group 1: Inhibition of acetyl-coenzyme A carboxylase (ACCase), e.g., sethoxydim (Segment) and fluazifop (Fusilade II).
  
  
• Group 2: Inhibition of acetolactate synthase (ALS inhibitors), e.g., foramsulfuron (Revolver).
  
  
• Group 3: Inhibition of microtubule assembly, e.g., dithiopyr (Dimension) and prodiamine (Barricade).
  
  
• Group 5: Photosystem II inhibitors/serine 264 binders, e.g., metribuzin (Sencor).
  
  
• Group 9: Inhibition of 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase, e.g., glyphosate (Roundup).
  
  
• Group 10: Glutamine synthetase inhibition, e.g., gluphosinate (Finale).
  
  
• Group 14: Inhibition of protoporphyrinogen oxidase, e.g., oxadiazon (Ronstar).
  
  
• Group 15: Inhibition of very-long-chain fatty acid synthesis, e.g., metolachlor (Pennant Magnum).
  
  
• Group 22: Photosystem I electron diversion, e.g., paraquat and diquat.
  
  

Resistance to dinitroaniline, pyridine and other Group 3 chemical families is of particular concern regarding goosegrass control as it includes the commonly used herbicides dithiopyr (Dimension), prodiamine (Barricade), pronamide (Kerb) and pendimethalin (Pendulum). These “root inhibitor” preemergence products are often foundational parts of chemical control programs and resistance is problematic for turf managers who have long relied on spring applications of these active ingredients for control of goosegrass and other weeds. Resistance to ALS inhibitors is another major concern as the chemical families comprising this mode of action include many common goosegrass herbicides, particularly the sulfonlyureas. Oxadiazon, which has gotten a lot of attention recently in both warm- and cool-season turf, has confirmed cases of resistance in Virginia and North Carolina. 

HRAC maintains a complete classification of all herbicide modes of action that is a great resource for practitioners. Unfortunately for golf course superintendents, herbicide resistance issues aren’t getting any better and will likely affect more products in the future.

Cultural Control Strategies: The Best Offense Is a Good Defense

It’s often said the best weed control is a healthy stand of turf with no voids or weak areas – this absolutely applies to controlling goosegrass. It easily outcompetes desirable turfgrass species in places where the turf is struggling, like areas that have been weakened due to traffic and/or compaction. Thin or bare areas also allow more direct sunlight to hit the soil, providing the soil temperature fluctuations and light needed for seed germination. Implementing strategies that promote a dense stand of turfgrass is just as important as any herbicide applications you make. Research has found that goosegrass growth is greatly reduced, up to 90% less, in a dense turf canopy compared to seeds planted in a divot or bare soil (Busey, 2024).
 

Goosegrass is responsive to fertilizer but isn’t necessarily reliant on nitrogen to proliferate, so supply turf with adequate fertilizer to maintain a dense canopy, particularly in spring and fall, or when goosegrass isn’t present. Light and frequent irrigation keeps the soil surface moist and encourages goosegrass seedling survival and growth. A deep and infrequent irrigation strategy is advantageous for discouraging goosegrass establishment, since turfgrasses typically have deeper roots than goosegrass seedlings. A key consideration for superintendents is that the efficacy of some goosegrass herbicides can be affected by soil moisture and care needs to be taken that adequate soil moisture is present for good weed control. 

Goosegrass is considered an indicator of soil compaction. Superintendents should implement traffic management strategies combined with proper fertilization to increase the competitiveness of desirable turfgrass relative to goosegrass. If compaction limits turf growth, do not hesitate to aerify even if you have applied a preemergence herbicide. While most labels recommend not aerating following application, multiple studies indicate that aerifying after a preemergence application will not disrupt the herbicide “barrier" in the soil. A recent study on hybrid bermudagrass in Florida showed that aerification did not influence the level of goosegrass control or make the grass more vulnerable to herbicide injury (Petelewicz, 2025). 

One exception is late-summer core aeration of creeping bentgrass greens, which can create ideal conditions for goosegrass germination. On all cool-season playing surfaces, if goosegrass infestations are severe, seeding any weak or highly affected areas in late summer or early autumn with desirable grasses will fill the voids created as goosegrass plants die and significantly decrease goosegrass seedling survival the following spring. 

Mechanical removal can be an effective strategy on high-value surfaces like putting greens, collars and tees. Goosegrass is an annual plant that can’t regrow if the crown is removed. Immature plants can be removed easily, but mature plants have a large central taproot and can be difficult to remove. Handpicking goosegrass plants is time consuming and may be impractical on large areas like fairways, but it does give immediate results. Considering that one plant can drop nearly a quarter-million seeds, handpicking will certainly help to reduce future goosegrass pressure. Mapping infested areas is also worthwhile and provides vital information for next year’s weed control program, especially in light of new acreage limits on oxadiazon.
 

Chemical Control Strategies in Cool-Season Turfgrass 

Incorporating Oxadiazon Into Traditional Preemergence Control Programs

While dithiopyr and prodiamine are often the foundation of herbicide programs for control of crabgrass and other annual grasses, it has become more common to see substantial and widespread goosegrass breakthrough where these herbicides have been used for many years. On golf courses where this occurs, we often find goosegrass biotypes with resistance to these herbicides. In such cases, the preemergence herbicide oxadiazon typically provides excellent goosegrass control when applied at the proper rate and timing. Oxadiazon continues to be a leading industry standard for preemergence goosegrass control and it has a different mode of action than dithiopyr and prodiamine, so biotypes resistant to those active ingredients are still susceptible to oxadiazon. 

Research has found it is difficult to predict goosegrass emergence throughout the growing season, but it typically begins four to six weeks after forsythia full bloom when daytime high temperatures reach 80 F for a few days and requires the soil temperature thresholds mentioned earlier. Oxadiazon needs to be applied before any emergence occurs since there is no early postemergence activity. Careful monitoring of weather trends, phenological indicators, soil temperature and/or emergence-tracking websites is needed to properly time all preemergence applications.

Getting comfortable with a new preemergence herbicide is an important part of the process so that you are not questioning whether the change in your herbicide program is causing issues later in the season. It makes sense to get comfortable with oxadiazon by using it only on your most-problematic areas in the first year and using it more widely in subsequent years. One advantage of oxadiazon is that it targets shoot growth and does not inhibit root development in turfgrasses, but there are a couple of things to keep in mind to prevent turfgrass injury. As mentioned earlier, oxadiazon is an HRAC Group 14 herbicide (protoporphyrinogen oxidase (PPO) inhibitor) that is active on shoot tissue. For a safe application to mature turf, you want minimal contact of the herbicide with green leaf tissue. To accomplish this, oxadiazon should be applied on a granular carrier to dry turfgrass and watered in as soon as possible to move the herbicide into the soil. Research trials have shown some transient injury when oxadiazon is applied to dew-covered turf. Avoid applying before a heavy rain event which will result in herbicide moving into standing water and being absorbed by turfgrass leaf tissue. While liquid formulations of oxadiazon can be used on dormant warm-season turf, they should never be used in cool-season turf. 

In terms of goosegrass control, results will vary depending on soil and environmental factors, but there is typically excellent goosegrass control when oxadiazon is applied once at 3.0 pounds of active ingredient per acre. A 2.0-pound-per-acre rate can be less effective in severe infestations, and the maximum single application rate is 4.0 pounds per acre (recent oxadiazon label changes are described in detail in the warm-season control section below). One strategy is to start at 3.0 pounds of active ingredient per acre and then increase the rate the following year if control doesn’t meet your expectations. Another important note is that oxadiazon is less effective against crabgrass than goosegrass. In areas with a history of severe crabgrass infestation, do not abandon your standard preemergence herbicide programs; use oxadiazon in addition. 

Finally, another key point regarding oxadiazon is that the size of the granule (size guide number or SGN) is critical. Just binding oxadiazon to any old coarse fertilizer is not a recipe for success, smaller prills work much better. Large-SGN formulations won’t result in the coverage needed to ensure goosegrass shoots encounter the herbicide as they emerge through the top layer of soil. Although sprayable formulations provide better coverage and typically cost less than granular, it is important to note that they are not labeled for cool-season use and are very risky to the turf.

Goosegrass Control on Cool-Season Putting Greens

Where preemergence control is needed on creeping bentgrass greens, bensulide (Bensumec) or bensulide + oxadiazon (The Andersons Goosegrass and Crabgrass Control) can be applied to putting greens and bensulide alone has shown to be safe on colonial bentgrass in research trials. Both bensulide and oxadiazon need to be watered in immediately after application. Applying these herbicides only to areas of greens with a history of goosegrass and crabgrass problems is a good approach. For example, superintendents often have success with just one pass with a rotary spreader or sprayer to the putting green perimeter (collar and cleanup pass area), being careful not to overlap. Cool-season turf managers using The Andersons Goosegrass and Crabgrass Control must remember the new oxadiazon label changes apply to that product as well.

On creeping bentgrass putting greens, researchers are also seeing promising goosegrass control from the class B plant growth regulator (PGR) flurprimidol (Cutless), especially compared to turf treated with trinexapac-ethyl or prohexadione-calcium (Peppers et al., 2024). With limited control options on greens, this strategy is a good way superintendents can attack goosegrass using a product with other benefits as well, such as Poa annua reduction and improved surface performance. Applications of flurprimidol at 10-12 ounces every two weeks result in excellent goosegrass control and better turf quality.
 

Postemergence Control Strategies

Fortunately, there are effective postemergence herbicide options, although control is particularly challenging in creeping bentgrass fairways. Topramezone (Pylex) and fenoxaprop (Acclaim Extra) are the main choices. Pylex can be applied up to 0.25 ounces per acre in creeping bentgrass and 1.0 to 1.5 ounces per acre in tall fescue, perennial ryegrass and Kentucky bluegrass. At 0.25 ounces per acre and lower, Pylex won’t control goosegrass with multiple tillers, so repeat applications every two to three weeks are needed. It’s best to begin treatment as soon as goosegrass is visible, ideally before it starts tillering. Pylex causes temporary (seven to 14 days) bleaching of creeping bentgrass at 0.25 ounces, so superintendents often use lower rates and sequential applications to minimize this effect. Including 0.5% by volume of a methylated seed oil (MSO) adjuvant improves the efficacy of Pylex. Researchers have looked at several other additives that could potentially reduce bleaching from Pylex, including chelated iron and triclopyr (Turflon Ester), but results have been inconsistent (Boyd et al., 2021; Cox et al., 2017). Many factors contribute to the response of weeds and turfgrasses to herbicides and it is essential to test any new herbicide mixtures or "safeners" on a small area before making a broadcast application. 

Interestingly, a recently published paper shows that chlorothalonil fungicides applied at or near the same time as Pylex reduce goosegrass control (Peppers et al., 2023). Don’t mix them or spray products containing topramezone and chlorothalonil within the same short period of time, or your goosegrass control may suffer.

Acclaim Extra can be applied at up to 3.5 ounces per acre in creeping bentgrass, 28 ounces per acre in Kentucky bluegrass and 39 ounces per acre in tall fescue and perennial ryegrass. While higher rates will control larger plants, the bentgrass rate will only control early leaf-stage goosegrass. To achieve season-long control in bentgrass, multiple applications are required, starting before plants are visible above the turf canopy. One advantage of Acclaim Extra compared to Pylex (when used alone) is that Acclaim Extra does not cause bentgrass bleaching.

In non-bentgrass turf, the combination product of 2,4-D + MCPP + dicamba + carfentrazone (SpeedZone) is another option. While a single application of SpeedZone won’t control goosegrass with multiple tillers, tank-mixing with Pylex improves control and eliminates goosegrass bleaching caused by Pylex. In severe gooosegrass and crabgrass infestations, the bleaching of the actual target weeds (in addition to the turfgrass) can have a dramatic and undesirable appearance as weeds are controlled. Therefore, there is interest in reducing this symptom on both the weeds and turf. Another common tank-mixture with Pylex is quinclorac (Drive) and is colloquially known as “PyleDriver.” The addition of quinclorac does not improve goosegrass control or reduce goosegrass bleaching, but it does improve crabgrass and broadleaf weed control and nearly eliminates crabgrass bleaching caused by Pylex. These mixtures significantly reduce bleaching of the target weeds and to some extent the turfgrasses; however, there are many factors at play and superintendents should always be prepared for some degree of bleaching when using Pylex. 

Finally, it’s recommended to rotate which nonselective herbicides are used to control goosegrass in bunkers, cart paths or other non-turf areas. Goosegrass has shown resistance to all common nonselective herbicides used in the golf course maintenance industry.
 

Chemical Control Strategies in Warm-Season Turfgrass 

Preemergence Control Options

Postemergence control of goosegrass is a lot more difficult than preventing it from appearing in the first place, so preemergence control is critical. In many parts of the transition zone and southern U.S., the potential for goosegrass emergence has shifted to earlier in the spring. In some cases, goosegrass is emerging three to four weeks earlier than superintendents have been accustomed to. It’s critical for superintendents to monitor soil temperatures and other indicators of goosegrass germination for proper application timing. Hiring a contractor to bulk spread preemergence products is a common and economical application method often used by warm-season turf managers, yet superintendents are often at the mercy of contractor schedules. As emergence shifts earlier due to changing weather patterns, it’s important for superintendents to work with contractors and schedule bulk spreads well ahead of time to ensure preemergence is in place when needed. Bulk spreads of oxadiazon on a fertilizer carrier, often referred to as “kicker apps” are a popular option.

How To Maximize Oxadiazon Applications and Navigate Label Changes  

Similar to dithiopyr in cool-season turf, oxadiazon (Ronstar) has long been the foundation of warm-season turf preemergence programs and is often applied using the flowable formulation (Ronstar FLO) in addition to granular applications. As goosegrass emergence shifts earlier in the spring and later into the summer due to changing weather patterns, it’s vital for superintendents to adjust application timing and frequency so coverage is in place throughout the potential window of emergence. One application of Ronstar at 3.0 pounds of active ingredient per acre made in February is not likely to last the season in the Southeast.
 

Further complicating control are new label changes affecting Ronstar use on golf courses. The important changes superintendents need to know are that for Ronstar FLO, only one application can be made annually at a maximum of 3.0 pounds of active ingredient (122 fluid ounces of product) per acre. Ronstar can be applied to only 30% of all managed turf; this includes driving ranges, lawns and other areas as well as the golf course. Ronstar on fertilizer applications can be made after Ronstar FLO applications, but not vice versa and must remain under 6.0 total pounds of active ingredient per acre annually. Golf courses with “heavy weed pressure” can make two applications of granular oxadiazon only at 4.0 pounds of active ingredient per acre with an annual maximum of 8 pounds. There is a 60-day interval required between any application of oxadiazon regardless of rate or formulation, a new restriction that impacts courses in Florida and other parts of the Deep South in particular.

To navigate these changes, superintendents need to prioritize the most important surfaces and areas with heavy goosegrass pressure. Rotating different areas each year between root-inhibiting preemergence herbicides and oxadiazon can limit turfgrass root damage while keeping applications within the 30% total area limit. Similar to how Northern superintendents are learning to incorporate oxadiazon into preemergence programs due to resistance issues, Southern superintendents need to incorporate other herbicide options into their weed control programs to account for oxadiazon label changes. 

Other Preemergence Herbicide Options

Flumioxazin (StayGuard/SureGuard) is another good product for warm-season turf managers and is useful for picking up preemergence coverage of goosegrass later in the season as oxadiazon coverage diminishes. Flumioxazin also has activity against crabgrass and Poa annua. Superintendents need to exercise caution with flumioxazin because traffic after application can cause injury, and damage to bermudagrass roots can occur in certain conditions. Different flumioxazin formulations have different label restrictions on whether they can be applied to dormant or green, growing bermudagrass. Dimethenamid-p (Tower) is labeled for both warm- and cool-season grasses and is often used for Poa annua control but provides good goosegrass control as well.

S-metolachlor (Pennant Magnum) is another good preemergence option and is labeled for all warm-season grasses except seashore paspalum. Application rates of 1.3 to 2.6 pints per acre provide good goosegrass control as well as crabgrass and sedge control. Mixing s-metolachlor with prodiamine is a way some superintendents are extending control. It is important to mention that low-cut bermudagrass is more sensitive to root-inhibiting preemergence herbicides, like prodiamine, in the transition zone compared to the Deep South. A rotation off of root inhibitors to other products is recommended at least every three years in the transition zone. 

Finally, indaziflam (Specticle) is a staple of many warm-season herbicide programs and provides good preemergence goosegrass control. Indaziflam is suspected to reduce bermudagrass vigor in the shoulder seasons and is recommended for use mainly in the middle of the summer or when warm-season turf is actively growing.
 

Goosegrass Control on Warm-Season Putting Greens

Pethoxamid (StriCore) is commonly used for Poa annua control but is an effective new tool for combating goosegrass in bermudagrass putting greens. Whether on greens or other playing surfaces, it’s best used in combination with other options with longer residual effect. It’s also been shown to be safe on creeping bentgrass putting greens. Warm-season turf managers using The Andersons Goosegrass and Crabgrass Control on putting greens must remember the new oxadiazon label changes apply to that product as well. Using the PGR flurprimidol to control goosegrass was discussed earlier and is an approach that can also work in warm-season greens. However, bermudagrass is much more sensitive to class B PGRs than creeping bentgrass, therefore other options may be safer.

Postemergence Control Strategies

Superintendents will be familiar with many of the common postemergence herbicide strategies used for goosegrass control in warm-season turf, such as foramsulfuron (Revolver) and Speedzone (discussed earlier in the cool-season control section). A list of several of those products can be found above in Table 2. The following are some recent trends in postemergence goosegrass control that can also help superintendents.

Metribuzin (Sencor) is a very effective postemergence option for warm-season turf managers and use has increased in recent years. It is critical to water in the product immediately to achieve the best control. Sequential applications of Sencor at 4 ounces of product per acre mixed with Pylex at 0.25 ounces of product per acre reduces bleaching from Pylex and results in excellent goosegrass control. This mixture should include 0.5% by volume of MSO and does not need to be watered in.

Trifloxysulfuron + metcamifen (Recognition) combines an ALS inhibitor with a safener and is a great option for goosegrass control, especially in zoysiagrass or St. Augustine grass. Combining Recognition at 1.95 ounces per acre with fluazifop (Fusilade II) at 24 fluid ounces per acre is a more-aggressive way to attack severe goosegrass issues in zoysiagrass.
 

What Does the Future Hold?

Changing weather patterns are already impacting goosegrass’ life-cycle and may create bigger challenges in the future. Short-lived perennial goosegrass already exists in Florida, and reports of perennial goosegrass ecotypes have been made in the Carolinas as well. Goosegrass emergence also continues to shift earlier into the spring and later in the summer, and perhaps even into the early fall. This makes extending chemical control throughout the growing season even more important, as well as getting control in place quickly in spring.

Lastly, turfgrass research scientists are hard at work studying goosegrass and there is still much to learn, including knowing more about how it develops herbicide resistance, when seeds become viable, and how changing weather patterns will affect the periodicity and life-cycle of the plant. Technology will most certainly play a role in the future of goosegrass control. Whether it’s in the form of better lab tools for researchers to analyze plant genetics or new equipment that superintendents can use for targeted herbicide treatments, turf weed science is advancing at a rapid pace. “Smart sprayers” that use machine vision and artificial intelligence are in the late stages of development and are scheduled to be released for use in golf in the near future. These marvels of modern technology will have the ability to “see and spray” goosegrass and other weeds. Just load the tank, tell the computer what types of weeds or weed species you want to target, and drive. The growth habit of goosegrass and other weeds makes them rather easy for software to distinguish from desirable grasses in a stand of turf, making autonomous identification and control more feasible than with Poa annua, for example.

The future holds promise for better goosegrass management options and weed science in general. But for now, it’s important to use a range of effective strategies if you want to get a grip on goosegrass.

Authors’ Note: We would like to acknowledge Dr. Shawn Askew of Virginia Tech and Dr. Jim Brosnan of the University of Tennessee for their contributions to this article.

References

Boyd, A.P., McElroy, J.S., McCurdy, J.D., McCullough, P.E., Han, D.Y., & Guertal, E.A. (2021). Reducing topramezone injury to bermudagrass using chelated iron and other additives. Weed Technology, 35(2), 289-296.

Busey, P. (2024). Goosegrass seedling emergence and growth in bermudagrass canopy and divots. HortScience, 59(8), 1182-1185. https://doi.org/10.21273/hortsci17949-24

Chuah, T.S., Salmijah, S., Teng, Y.T., & Ismail, B.S. (2004). Changes in seed bank size and dormancy characteristics of the glyphosate‐resistant biotype of goosegrass (Eleusine indica [L.] Gaertn.). Weed Biology and Management, 4(2), 114-121.

Cox, M.C., Rana, S.S., Brewer, J.R., & Askew, S.D. (2017). Goosegrass and bermudagrass response to rates and tank mixtures of topramezone and triclopyr. Crop Science, 57(S1), S-310.

Nishimoto, R.K., & McCarty, L.B. (1997). Fluctuating temperature and light influence seed germination of goosegrass (Eleusine indica). Weed Science, 45(3), 426-429.

Patel, J., Hall, N.D., Harris, J.R., & McElroy, J.S. (2023). Morphological and metabolic differences between turfgrass and row-crop biotypes of goosegrass (Eleusine indica). Crop Science, 63, 1602-1612. https://doi.org/10.1002/csc2.20933

Peppers, J.M., Elmore, M.T., & Askew, S. D. (2023). Evaluation of goosegrass response to combinations of topramezone and chlorothalonil. Weed Technology, 37(5), 554-559.