Annual Trampweed

Revised by Joey Williamson HGIC Horticulture Extension Agent, Clemson University, 11/09. Originally prepared by Joey Williamson, HGIC Horticulture Extension Agent, Clemson University. New 12/08. Pesticides Updated 10/16.

HGIC 2319

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Has your lawn been invaded by a weed that goes to seed in early summer with white, fluffy, dandelion-like seeds? This invasive, winter annual weed is Facelis retusa, or annual trampweed. It’s been in South Carolina for decades, but with decreased annual rainfall in recent years, this highly competitive weed is colonizing any bare spaces in drought-stressed and low-fertility lawns and roadsides. 

Annual trampweed (Facelis retusa)
Annual trampweed (Facelis retusa)
Joey Williamson, Clemson University HGIC

Annual trampweed is a low-growing, broadleaf weed with narrow, alternate foliage. The upper leaf surface is a dull green, and the lower surface has white tufts of long hairs. The plant has freely-branching stems that have a prostrate and spreading habit.

Cultural Control

To significantly control annual trampweed in lawns, homeowners must improve growing conditions for their lawns. A healthy and thick lawn will out-compete annual trampweed, and shade the soil to reduce trampweed seed germination in the fall. Proper turfgrass care includes taking a soil sample, applying the correct amount of dolomitic limestone to adjust the soil pH for optimum grass growth, and fertilizing the grass at the correct times with the appropriate lawn fertilizers see HGIC 1201, Fertilizing Lawns.

With the reduced rainfall levels in recent years, turfgrass may need supplemental watering. Under most conditions, lawns in South Carolina require rainfall to be supplemented with irrigation for a total of one inch per week see HGIC 1207, Watering Lawns. Implementing the proper mowing height for your turfgrass species is also important to maintain a thick grass stand see HGIC 1205, Mowing Lawns.

If allowed to go to seed, one can reduce annual trampweed spread culturally by using a bagger on the lawnmower to catch the seeds along with the clippings.

Chemical Control

By the time annual trampweed makes its fluffy, white seed heads in early summer, it is too late to use post-emergence chemical control.

Weed Control in Warm-Season Turfgrass: In warm-season grass lawns (such as bermudagrass, centipedegrass, St. Augustinegrass and zoysiagrass), a broad-leaf weed killer (post-emergence herbicide) should be applied in November and again in February, if needed.

A 3-way, broadleaf herbicide that contains 2,4-D, dicamba, and mecoprop (often abbreviated as MCPP) will control annual trampweed. These are liquid concentrates that are mixed with water in a pump-up sprayer and sprayed on broadleaf weeds in the lawn. See Table 1 for examples of brands and products.

Always follow the product label for application rates and safe use. Notice on the product labels that for use on centipedegrass or St. Augustinegrass, a reduced rate of 3-way herbicides should be used. The two applications of these herbicides will kill any trampweed seedlings that germinated in the fall and those that germinated in the late winter. Do not apply broadleaf weed killers to any warm-season lawns during turfgrass green-up in the spring, as they may severely injure the lawn.

Alternatively, atrazine may be used for annual trampweed control, but only on centipedegrass and St. Augustinegrass. Apply atrazine spray to annual trampweed in November and again in February. A maximum of two applications per year is permitted. Do not apply atrazine during the spring green-up of these warm-season turfgrasses, especially centipedegrass and St. Augustinegrass, as significant injury to the lawn may occur. See Table 1 for examples of brands and products. Follow the directions on the product label for application rate and safe use.

Weed Control in Cool-Season Turfgrass: In turfgrass tall fescue lawns that are typically over-seeded annually in October to maintain a thick grass cover, the application of a 3-way, post-emergence, broad-leaf weed killer should be delayed until February and then applied again in March. This will kill the trampweed plants from seed that germinated during the fall and spring. The early fall application is not made because this type of herbicide can injure tender, young fescue seedlings. See Table 1 for examples of brands and products. Follow the directions on the product label for application rate and safe use.

Alternatively, herbicides containing triclopyr may be used on tall fescue lawns to control annual trampweed. Make applications in February and again in March. Some products have a lower concentration of triclopyr in their mix, and these may be used also on zoysiagrass and bermudagrass. On these two warm season turfgrasses, apply one of these reduced rate triclopyr products in November and again in February. Follow the directions on the product label for application rate and safe use. See Table 1 for examples of brands and products.

Product Labels & Safe Use: In choosing a lawn weed killer, be sure to look at the product label. It will state onto which lawn species the product can safely be applied and which weeds will be controlled. Many consumer brands have several products with very similar names. A particular product may come in as many as three different forms: a concentrate to put into a pump-up sprayer, a ready-to-spray container with built-in sprayer, and a hose-end container that attaches to the garden hose. Sometimes the active ingredients are different in each of the three product forms. The best advice is: read the label for the active ingredients in the product, look for the weed to be controlled on the label, and make sure it can be used safely on your lawn species and at what time of year.

Remember that your trees and shrubs are broad-leafed plants, and all of the above herbicides can injure or kill them. Most deciduous trees and shrubs have lost their leaves by November and will not have leafed-out again by early March, so applications during these late fall and winter periods are less likely to affect them. However, do not spray heavily around the root zones of these ornamentals, as many herbicides can be taken up by plant roots. Fortunately, annual trampweed seems to be worse in most cases out in sunny areas of the lawn and far enough from trees and shrubs to not be a problem.

 
Table 1. Examples of Post-emergence Herbicides for Annual Trampweed Control in Lawns.
Brands & Specific ProductsHerbicide Active Ingredients% Active Ingredient in ProductTurfgrass Labeled for Use
Note: There are many broadleaf weed killers in the stores, and many are similar to the 3-way herbicides, but have additional weed killers added to the mix. They may also work to control annual trampweed, but these additional components often restrict to which type of lawn they can be applied. Be sure to read the label for mixing rate and on which lawn it can be applied.
Ferti-lome Weed-Out Lawn Weed Killer (Concentrate) 2,4-D
Mecoprop
Dicamba
5.88%
5.45%
1.21%
Centipedegrass
St Augustinegrass
Bermudagrass
Zoysiagrass
Tall Fescue
Southern Ag Lawn Weed Killer with Trimec® (Concentrate) 2,4-D
Mecoprop
Dicamba
3.05%
5.30%
1.29%
Centipedegrass
St Augustinegrass
Bermudagrass
Zoysiagrass
Tall Fescue
Bonide Weed Beater Lawn Weed Killer Concentrate 2,4-D
Mecoprop
Dicamba
7.59%
1.83%
0.84%
Centipedegrass
St Augustinegrass
Bermudagrass
Zoysiagrass
Tall Fescue
Hi-Yield Atrazine Weed Killer Atrazine 4.0% St Augustinegrass
Centipedegrass
Southern Ag Atrazine St Augustine Weed Killer Atrazine 4.0% St Augustinegrass
Centipedegrass
Image Herbicide for St Augustine & Centipede with Atrazine Atrazine 4.0% St Augustinegrass
Centipedegrass
Bonide Chickweed, Clover & Oxalis Killer Concentrate (Ready to Spray) Triclopyr
2,4-D
Dicamba
1.56
13.72
1.35
Tall Fescue
Zoysiagrass
Bermudagrass
Monterey Spurge Power Conc. Triclopyr
MCPA
Dicamba
5.00
56.14
3.60
Tall Fescue
Bermudagrass
Zoysiagrass
Ortho Weed B Gon Chickweed, Clover & Oxalis Killer For Lawns Triclopyr 8.00 Tall Fescue
Zoysiagrass (at low rate)
Hi-Yield Turflon Ester Ultra Herbicide Triclopyr 61.6 Tall Fescue
Monterey Turflon Ester Triclopyr 61.6 Tall Fescue

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This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.