Black medic weed control

White clover and black medic infesting turf

Once again, the broadleaf weeds black medic (Medicago lupulina) and white clover (Trifolium repens) are infesting turf. These weeds are commonly found growing on low fertility, low maintenance sites such as roadsides, boulevards and neglected home lawns.


Black medic in a lawn

The characteristic that makes these species competitive in low fertility sites is the fact that they host rhizobacteria that fix atmospheric nitrogen into plant-available nitrogen. Of course with the extended start to the growing season, the typical fertilizer programs may result in some leaner than normal turf as application intervals may be stretched to the limit, thereby making these weeds even more competitive with hungry turf.

The most effective herbicides for controlling black medic and white clover contain the active ingredient clopyralid, fluroxypyr or quinclorac. In unirrigated turf, ensure there is adequate soil moisture before trying to control the weeds. In irrigated turf, and if it’s a serious weed infestation, you may want to control the weeds now to prevent a complete takeover and then make another application in the fall to clean up any misses or weeds that didn’t quite get eliminated.

Always remember to read and follow label directions when applying herbicides. Please see www.msuturfweeds.net for all your turfgrass weed identification and management recommendations.

Dr. Frank’s work is funded in part by MSU’s AgBioResearch.

Colorado State University

Wet, cool springs and early summers promote prolific growth of two legume family weeds in lawns, white clover (white flowers) and black medic (yellow flowers). Leguminous weeds can be both common and competitive in lawns that have not been fertilized adequately with nitrogen for a couple of years. Regular fertilization, especially late season (September-early November) nitrogen applications, can help reduce these weeds. Summer herbicide treatments aren’t as effective as fall applications, but enough control can be realized to justify professional sprays.

To maximize weed control and prevent turf injury, follow these guidelines:

  • Ensure that the lawn is well-watered and not under stress.
  • Don’t apply broadleaf herbicides when temperatures are above 85 F. Control may be reduced, turf may be injured, and the herbicide is more likely to volatilize and harm non-target plants at high temperatures.

Spot treatment is preferable to broadcast applications with any post-emergent herbicide because of the lessened potential for harming non-target plants in the landscape. Post emergent herbicides such as Bayer Advanced All-In-One Lawn Weed & Crabgrass Killer, Ortho® Weed B Gon MAX® Plus Crabgrass Control, Spectracide® Weed Stop® for Lawns Concentrate plus Crabgrass Killer provide rapid and effective control of clover and other leguminous weeds. On non-residential lawns and golf courses, products containing clopyralid (Confront, Millenium) provide excellent control. Three-way herbicides containing dicamba and MCPP/MCPA (Trimec products, Speed Zone, Power Zone, Surge, Q4) can also provide good control of clover and black medic.

As always, an adequately fertilized, dense, healthy lawn is the best preventative against weeds.

Tell us what you think!

Do you have a question? Try Ask an Expert!

Black Medic Control: Information On Getting Rid Of Black Medic

Black medic weed is a minor nuisance in the garden. While it can be an issue, once you know why black medic grows where it does, you can easily get rid of black medic and improve your soil at the same time. Believe it or not, you may actually come to be glad that black medic invaded your garden.

Identification of Black Medic Weed

Black medic (Medicago lupulina) is considered an annual clover (but is not part of the clover genus). It has the teardrop-shaped leaves that are often found on clovers but, unlike other clovers, has yellow flowers. It is normally an annual, but in some warmer areas it can survive for several years before dying.

Like many clovers, the leaves grow in groups of three and are oval shaped. Small pom-pom like yellow flowers will bloom off stems that grow off of the stem of each group of leaves.

How to Get Rid of Black Medic

Before you start spraying chemicals or getting on your hand and knees to remove black medic, you should first understand the conditions that black medic weed likes to grow in. Black medic grows in compacted soil. This is why you most commonly find it growing by the roadside or next to sidewalks, where soil has been compacted by wheel and foot traffic.

If you find it in the middle of your lawn or flower bed, you may be able to get rid of black medic for good simply by correcting your over compacted soil. In other words, black medic weed is an indicator that your soil has problems.

You can correct compacted soil by using a machine to aerate the soil or by amending the soil with additional organic material. Oftentimes, just taking steps to aerate the soil will not only remove black medic but will result in a healthier lawn and flower bed.

If mechanical aeration or amending the soil is not possible or does not fully succeed at getting rid of black medic, you can fall back on more traditional methods of weed control.

On the organic side, you can use manual pulling for black medic control. Since the plant grows from a central location, hand weeding black medic can be very effective and remove it from large areas in a short time.

On the chemical side, you can use non-selective weed killers to kill black medic. Please be aware that non-selective weed killers will kill any plant that they come in contact with and you should be careful when using it around plants you wish to keep.

Note: Chemical control should only be used as a last resort, as organic approaches are safer and much more environmentally friendly.

Black Medic (or Yellow Trefoil)

Cultural control: Some annual weeds can be controlled by mowing, yellow trefoil tolerates mowing because of its low growing habit. Reduce compacted soils by aerating at least once a year and then follow that up by overseeding to fill in bare and thin areas.

Remove the weed before it produces seeds: Control of black medic starts by reducing seed populations – its seeds remain viable several years.

Hand weeding: Hand pulling helps reduce infestations.

Chemical control: Use a pre-emergent herbicide in the spring to prevent weed seed germination. Pre-emergents are especially effective in areas were black medic was a problem the previous year.

Broadleaf herbicides work best when applied in early spring or fall when the plant is young and actively growing. Products that contain 2,4-D, MCPP, dicamba, clopyralid or triclopyr as an active ingredient can successfully control the plant and work better than 2,4-D applied alone.

Glyphosate (roundup) is non-selective and can also be used to kill yellow trefoil in landscape beds, and along curbs, sidewalks and driveways.

Vinegar-based (20% acetic acid) and Citric Acid herbicides are considered a natural organic weed killer. They can be used as a non-selective herbicide in place of glyphosate and will kill annual weeds.

Weed Identification

Stems: The prostrate stems are angled, slender and hairy. They branch and spread along the ground from the taproot.

Leaves: Green, compound leaves with three oval-shaped leaflets up to 1/2 inch long, arranged alternate along the stem. The leaflets have toothed margins and a small point on the tip. The center leaflet is on a short stalk, while the lateral leaflets are attached to the petiole.

Flowers: Small, round, bright yellow flowers in clusters that are about 1/2 inch long.

Fruit: Tiny pods that turn black when ripe. One seed is produced per pod. The seeds look like little brown kidney beans.

Root: Grows a deep taproot.

Black Medic

(More Lawn Weeds)

Black Medic
Medicago lupulina


Photo: Black Medic, Medicago lupulina

General description

Black Medic is usually first noticed when it produces numerous round yellow flowers in clover like clusters. Flowers eventually form black seedpods that persist on dark brown to black prostrate stems. A legume that is a summer annual with alternate compound leaves with 3 leaflets that closely resembles clover. Toothed stipules are present at the petiole bases. Forms a shallow taproot with small nodules. Often mistaken for wood sorrel (Oxalis).


Closeup of black medic

Management In Lawns

  • Cultural practices
    Maintain healthy, dense turf that can compete and prevent weed establishment.
  • Mechanical Management
    Hand pulling or using an appropriate weeding tool are the primary means of mechanical weed control in lawns. This is a viable option at the beginning of an infestation and on young weeds. Hand pulling when the soil is moist makes the task easier. Weeds with tap roots like dandelions or have a basal rosette (leaves clustered close to the ground) like plantain are easier to pull than weeds such as Bermudagrass (wiregrass) or creeping Charlie (ground ivy) that spread with stolons or creeping stems that root along the ground.
  • Chemical Treatment in Lawns
    Herbicides should be used as a last resort because of the potential risks to people, animals, and the environment. Be aware of these precautions first.
    If you chose this option, spot treat weeds with a liquid, selective, postemergent, broadleaf weed killer applied when weeds are actively growing. Look for a product with one or more of the following active ingredients:
    2, 4-D, MCPP (mecoprop), Dicamba* or Triclopyr.
    *Do not spray herbicides containing dicamba over the root zone of trees and shrubs. Roots can absorb the product possibly causing plant damage. Refer to the product label for precautions.
  • Organic Lawn Herbicides

Today I plan on making a post on the differences between hop clover and black medic, and then later the difference between the three species of Ohio locust trees; black, honey, sunburst.
Hop clover and black medic are very difficult to distinguish from each other. They both have very similar leaves, 3 leaves that look like those of the white clover. Their flowers look like those of white clover, only much smaller, and yellow. Both species can grow up to 1-2 feet tall. So with all that information, lets look at a few easy ways to tell them apart.
Black Medic

Black Medic

Black Medic grows to be anywhere from 1-2 feet tall. It seems to be able to be found anywhere (forests, fields, roadsides) and can be commonly found in rather poor soil. Black medic forms a fain amount of branches from the base of the plant. It has compound leaflets with 3 small oval shaped leaves. The center leaflet is slightly longer, and is on a longer stalk than the side leaves. Each leaf has a distinctive “tip” at the end. The flowers are anywhere from 1/8″-1/6″ long and are yellow. They are clustered on short stems that emerge from the leaf axil. Each half-inch cluster is composed of up to 50 individual flowers.
Hop Clover

Hop Clover

Hop clover usually grows up to around 1 foot tall. They have a reddish-green sprawling stems. Once again, the leaves are compound, composed of 3 leaflets, the middle one being on a longer petiole.The flowerhead is yellow and can be up to half an inch long. It consists of 15-40 small individual flowers. Hop clover is most commonly found around meadows and along the edges of trails or roads.
Black medic and hop clover are difficult to distinguish from each other. There are two ways I use to tell them apart. Black medic has a “point” at the end of each leaflet. Hop clover has a smother tip. Black medic has a longer center leaflet, surrounded by two shorter leaflets. Hop clover’s leaflets are around the same size.
Not only do they look like each other, but they also look similar to many other Ohio plants (yellow wood sorrel, red clover, white clover). Yellow wood sorrel has heart-shaped leaves, while black medic and hop clover have oval leaves. Red clover has dark check marks on its leaves, its leaves also being larger than those of hop clover and black medic. White clover sometimes has white blotches on its leaves. The easiest ways for me to tell white clover from black medic and hop clover are the white flower of white clover, and the leaflets of white clover have petioles similar in length.

Also Known As:

Japanese clover, black clover, hop clover, trefoil

Description

Black medic, Medicago lupulina L., is a Eurasian native that is normally an annual but can act as a perennial in some settings. Primarily a weed of turfgrass, this legume (closely related to alfalfa) is a low-trailing plant that reproduces from seed and has a deep taproot in areas where it survives longer than a year.Able to reach lengths of 1–2 feet, its stems are prostrate, 4-angled and branch from the base of the plant, radiating out from the tap root.The leaves are alternate and compound, consisting of 3 oval-shaped leaflets with toothed margins, prominent veins and slightly projecting tips. Longer than the 2 lateral leaflets, the central leaflet extends beyond them on a short stalk. Flowers bloom from late spring to early fall; the bright yellow flowers are small, 5-petalled, rounded to slightly elongated, and borne in dense, globe-shaped clusters. The flowers produce 1/8 inch long pods (the fruit of the plant) that are strongly curled, thick-walled and contain a single kidney-shaped seed; the pods blacken when ripe. Depending on growing conditions, a single plant can produce up to 6,600 seeds, which can remain viable in the soil for several years.

Photos by: Karin A Rawlins, University of Georgia, Bugwood.orgPhotos By: Forest & Kim Starr, Starr Environmental, Bugwood.orgPhotos By: Forest & Kim Starr, Starr Environmental, Bugwood.orgPhotos by: Karin A Rawlins, University of Georgia, Bugwood.org

Black medic may be confused with other weedy trifoliate legumes such as clover species and yellow woodsorrel; however, it can be distinguished by its yellow flowers, black seed pods and leaflets with their oval shape, serrated margins, longer stalked central leaflet, and small apex tips.

Black medic is nitrogen-fixing—its roots add nitrogen to the soil by forming an association with rhizobial bacteria. This weedy plant is able to adapt to a wide range of environmental conditions and is commonly found in lawns, waste areas, pastures, fields, gardens and along riverbanks and railways.

Control Methods

Cultural control: Maintaining a healthy plant community (well-watered, fertilization that balances nitrogen/phosphorus) and encouraging the plants to grow thick and tall are good ways to crowd out black medic. As always, it is prudent to reseed a disturbed site with perennial grasses or other desirable plants.

Mechanical/physical control: Small populations of black medic can be hand pulled when the soil is moist. The plant can also be removed by rototilling or hoeing. Mowing may not be feasible because of black medic’s low-lying growth habit.

Chemical control: Small populations can be spot treated with glyphosate (Roundup®), using care not to injure nontarget plants (including grasses and trees), which glyphosate will kill upon contact. A broadleaf lawn herbicide can also be used. Herbicides that contain triclopyr, dicamba, clopyralid, or 2,4-D combinations are generally effective if applied correctly, usually in early spring or fall when the plant is young and actively growing. More than one application may be necessary.

More information can be found in the PNW Weed Management Handbook

  • Use pesticides with care.
  • Apply them only to plants, animals, or sites listed on the label.
  • When mixing and applying pesticides, follow all label precautions to protect yourself and others around you.
  • It is a violation of the law to disregard label directions.
  • Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock.

Biological control: No biological control agents are available; however, a few fungi have been reported to infect black medic. The plant can be grazed and provides nutritious forage although it can cause bloating in cattle.

Photo credits included in pdf

View/Print pdf of this weed

Black Medic

Black Medic

Black medic is germinating everywhere! As things heat up and you start inviting friends out to barbeque, you might be noticing this pesky clover-like weed popping up in your lawn and gardens.

It’s around this time that black medic—sometimes called yellow trefoil, nonesuch, or hop clover—starts becoming a problem in certain lawns and gardens. It’s usually an annual but sometimes can stick around for even longer and is an annoying weed as well as an indicator of poor lawn conditions.

What does Black Medic look like?

Black medic may look like a clover, but it’s technically not. For starters, you’ll never get a four leaf clover from it—there are always three leaves, one further from the stalk and two closer. You’ll also find that black medic has yellow globe-like flowers, instead of the white you normally see in clovers. The seed pods are also distinct, turning black when ready to drop. You’ll want to get rid of black medic before this, as the seeds are its only way of reproducing and they can stay viable for years.

Insects and Disease

Not only is black medic not exactly very attractive, it can be host to insects as well as viral or fungal diseases that can kill the rest of your garden. Luckily, there are several ways to remove the problem. Hand weeding is a valid option, and best done when the soil is wet so the roots pull out cleanly.

Black medic loves compacted soil

As with most weeds, black medic appearing is a symptom of a bigger problem in your lawn or garden, and correcting the problem will often get rid of the weed itself. Black medic specifically loves dry, compacted soil such as roadsides, so if you’re having problems with it, consider core aerating your soil. Additionally, setting your lawn mower to a higher setting when mowing can help kill it off, because it does not do well in the shade. Finally, it does well in sparse and nitrogen-poor soil, so consider regular fertilization or adding organic material to your lawn or garden to help encourage nitrogen and discourage weeds.

If you are considering a herbicide, remember to consider going organic and be careful not to hurt the rest of your garden or lawn. Our Fiesta and Natria products do well at controlling it. If you can’t get black medic to go away or you decide you like it there, there are uses for it. For starters, over enough time it will correct the lack of nitrogen in your soil by creating some itself. The flowers and young leaves of black medic are edible, too, as are the seed pods, which can be ground up into flour. (With all self-harvested edible plants, please be wary of chemicals that may have poisoned the plants and be toxic to you and your family.)

Kansas State University

Black Medic (Medicago lupulina)

Black medic is warm season annual (sometimes biennial) that reproduces by seeds. It is shallow rooted with multi-branched slender, prostrate, slightly hairy stems spreading 12 to 24 inches. The alternately arranged, dark green leaves are compound with three small, (1/5 to 3/5 inch long), sparsely hairy, oval leaflets. The center leaflet is stalked and the side leaflets occur close to the stem. The 1/8 to 1/6 inch long bright yellow flowers are clustered on short stems that emerge from the leaf axils. Each cluster is approximately 1/2 inch long, round, and comprised of up to 50 individual flowers. Flowering occurs April to October.

Occurrence

Black medic occurs in a variety of turf settings, particularly in infertile, dry settings.

Non-Chemical Control

To control black medic without chemicals, maintain turf density and health using proper culture and mechanically pull removing as much plant as possible.

Chemical Control

Apply postemergence broadleaf herbicides during periods of active growth from late spring through early summer and again from early through mid autumn.

Additional Images

Leave a Reply

Your email address will not be published. Required fields are marked *