Have you found Black Medic in your lawn? Learn more about how to identify this weed, what conditions cause it and the best ways to remove and prevent it in the future. This species is often found growing in dry, marginal soils with thin turf that has not been fertilized with nitrogen. It tends to grow in a prostrate fashion, forming patches and is most noticeable when flowering during summer. Life cycle Black medic is Hi all! I’m a newbie gardener who has inherited a jungle of a garden in my recent house move.
Black Medic, also known as Medicago lupulina or Yellow Trefoil, is a Summer annual weed. This means that it germinates sometime in the late Spring, grows well during the heat of Summer, then dies off with the cold weather. Black Medic is sometimes referred to as Yellow Clover because it looks like Clover with teardrop-shaped leaves, but has a yellow flower. The seed pods of Black Medic are also unique. They turn black when they’re ready to drop. If you can remove the Black Medic before this happens, it will help eradicate the plant, as the seeds are its only way of reproducing and they can stay viable for years and throughout Winter.
What Causes Black Medic?
It’s important to understand the conditions needed for Black Medic to thrive. A little Black Medic is normal. It will fill in the bare areas during the heat of Summer. A lot of Black Medic however, typically indicates that your lawn is being mowed too short in the Spring and Summer, your grass types are not strong or healthy enough to compete with the weed or your soil is compacted. If you notice the Black Medic growing by the roadside or next to a sidewalk, this is a sign that your soil quality is compromised due to foot traffic and compaction is the underlying problem.
How To Get Rid Of Black Medic?
Since Black Medic has a short lifespan, the bulk of your effort should go towards improving your lawn to prevent this weed from populating the following year. But there are a few things you can do to eliminate the weed right away.
- Pick the Black Medic. If you’re able to do this when the soil is wet, that would be ideal, as the roots will more easily and cleanly pull out of the ground. Black Medic grows out of a central location, so hand weeding can be very effective for removing the weed from large areas.
- Another option for elimination is to use a natural weed suppressant, such as Weed Beater Fe, which will be successful in killing the weed, however it also causes stress on the surrounding grasses, so use it sparingly.
How To Prevent Black Medic?
Black Medic and other annual weeds will emerge where your lawn is not competing. It could be that you’re mowing your lawn too short, which is keeping your grasses from growing stronger than your weeds. It could also be that the grasses you have are too weak and old and just don’t fight that well. Another option is that you have dry, compacted soil. Luckily, there are several ways to address the issues that could be resulting in the Black Medic in your lawn.
- One of the worst things you can do for your lawn is remove too much of the grass blade in a single mowing. Removing more than 1/3 of the grass blade length in a single mowing will turn the grass brown, stop root growth, and invite in weeds. So set your mower blades high.
- Dull mower blades are another common mowing issue because they rip the grass, instead of cutting it. This leaves your lawn vulnerable to disease and weeds and also dehydrates the grass blades, causing them to turn brown. A hardware store should be able to sharpen your blades for you. Try to do this every 20 hours worth of cutting or at least once per season
- If you have older poor grasses, a total Lawn Renovation might be the best choice.
- If you don’t want to go that far, simply Slice Seeding your current lawn should make a big difference.
- Given that compacted soil is an ideal environment for Black Medic to grow, we recommend aerating your soil. You can do Core Aeration or Liquid Aeration. If you’d like a DIY solution for aeration, try Liquid Aerator on the areas where you’re noticing the problem.
- Lastly you can try our Organic Soil Builder application, which will add valuable organic matter and nutrients to your soil, serving as an organic fertilizer that will promote healthy and balanced grass growth.
Contact us to learn more or to get our opinion on what would be best for your specific situation.
Lawn and Turfgrass Weeds: Black Medic (Medicago lupulina L.)
This species is often found growing in dry, marginal soils with thin turf that has not been fertilized with nitrogen. It tends to grow in a prostrate fashion, forming patches and is most noticeable when flowering during summer.
Black medic is a member of the legume family (Fabaceae) and is classified as a winter or summer annual. Plants generate deep taproots and crowns produce long, spreading stems that grow prostrate along the soil surface but do not give rise to nodes and roots. This species produces flowers, fruits, and seeds from late spring to early fall. Like other legumes, black medic exists symbiotically with nitrogen-fixing Rhizobium bacteria which form nodules on roots and convert atmospheric nitrogen into a plant-available form.
Figure 2. Yellow inflorescences of black medic. A single inflorescence may contain up to 50 individual flowers. Photo: Peter Landschoot, Penn State
Black medic stems are sparsely hairy and grow close to the ground then turn slightly upright, giving rise to yellow flower clusters called inflorescences. Leaves have three oval leaflets (trifoliate arrangement) approximately 1 ⁄2 to 3 ⁄4 inch in length and arise alternately on stems. Leaf margins of individual leaflets are smooth at the base and slightly serrated towards the top, with a small spur at the tip. Black medic leaves can be distinguished from other clovers by the extended petiole on the center leaflet. A pair of leaflike stipules can be found at the junction of the main stem and each leaf.
Figure 3. Leaves of black medic showing central leaflets on extended petioles and small, leaflike stipules at the junction of stems and leaves. Photo: Peter Landschoot, Penn State
Small ( 1 ⁄4 to 1 ⁄2 inch), rounded yellow inflorescences develop on stalks that arise from leaf axils on stems. Each compact inflorescence is composed of multiple individual flowers which are eventually replaced by black seed pods and seeds. Seeds are viable and generate new plants. Flowering occurs throughout the summer months.
Management and control
Infestations of black medic can be reduced by improving turf density through fertilization, regular mowing, and use of turfgrasses well-adapted to site conditions. This weed can be suppressed or controlled with various postemergence herbicides, particularly those containing dicamba, MCPP, and/or fluroxypyr.
Some postemergence herbicide products labeled for control of black medic.
|Active ingredients||Product name(s)*|
|2,4-D and 2,4-DP||Patron 170 (ester formulation)|
|2,4-D, 2,4-DP, and dicamba||Super Trimec (ester formulation)|
|2,4-D, clopyralid, and dicamba||Millennium Ultra 2**|
|2,4-D, fluroxypyr, and dicamba||Escalade 2|
|2,4-D, fluroxypyr, triclopyr, and flumioxazin||Sure Power (ester formulation)|
|2,4-D, MCPP, dicamba||Trimec Classic, Threesome, Lesco Three-Way, 3-D|
|2,4-D, MCPP, dicamba, and carfentrazone-ethyl||Speedzone|
|2,4-D, MCPP, dicamba, and sulfentrazone||Surge|
|2,4-D, quinclorac, and dicamba||Quincept; 2DQ Herbicide; Triad QC Select, Triad SFZ Select|
|2,4-D, quinclorac, dicamba, and sulfentrazone||Q4 Plus|
|2,4-D and triclopyr||Chaser 2 Amine, Turflon II Amine|
|2,4-D and triclopyr||Chaser Turf Herbicide (ester formulation)|
|2,4-D, fluroxypyr, and triclopyr||Momentum FX2|
|2,4-D, fluroxypyr, triclopyr, and sulfentrazone||Momentum 4-Score|
|2,4-D, triclopyr, dicamba, and pyraflufen-ethyl||4-Speed XT (ester formulation)|
|2,4-D, triclopyr, dicamba, and sulfentrazone||Foundation|
|carfentrazone-ethyl and quinclorac||SquareOne|
|fluroxypyr, dicamba, and fenoxaprop-p-ethyl||Last Call Selective Herbicide|
|MCPA, fluroxypyr, and dicamba||Change Up|
|MCPA, fluroxypyr, and triclopyr||Battleship III|
|MCPA, MCPP, and dicamba||Trimec Encore, Tri-Power Selective Herbicide|
|MCPA, MCPP, dicamba, and carfentrazone-ethyl||Powerzone (ester formulation)|
|MCPA, triclopyr, and dicamba||Lesco Three-Way Ester II, Cool Power (ester formulation)|
|MCPA, triclopyr, and dicamba||Eliminate, Horsepower|
|MCPP||Mecomec 4 Turf Herbicide|
|quinclorac||Drive XLR8, Quinclorac 1.5 L, Quinclorac 75 DF|
|sulfentrazone and carfentrazone-ethyl||Dismiss NXT|
|sulfentrazone and quinclorac||Solitare, Solitare WSL|
|triclopyr and clopyralid||Confront**|
|triclopyr and fluroxypyr||Tailspin|
|2,4-D, triclopyr, dicamba, and sulfentrazone||Tzone SE (ester formuation)|
*Follow label precautionary statements, restrictions, and directions regarding tolerant turfgrass species, rates, and timing of applications.
**Clopyralid-containing products should not be used on residential lawns but can be used for treating weeds in non-residential turf.
Hilty, J. 2017. Illinois Wildflowers. Black medic.
Uva, R.H., J.C. Neal, and J.M. DiThomaso. 1997. Weeds of the northeast. Cornell Univ. Press. 397 pp.
Weed with black pods
Hi all! I’m a newbie gardener who has inherited a jungle of a garden in my recent house move. Please could anyone help me identify a weed with black pods which has spread rapidly in my front garden? The pods are shooting seeds across the plant beds so it’s growing quickly. I am currently trying to get rid of it but worried that it will continue to come back as I cannot identify a root. Any help will be greatly appreciated!
Lots of plants have black pods. Can you do a photo, or a fuller description, shape of leaves, colour of flowers, height, any else about it
I have photos but not sure how to upload it to this forum? It has long arching stalks that are tangled between all the other plants and small (elongated oval) leaves.