Weed of the Month: Black Medic
 | Author:
Allison Kosto, MSU Broadwater County Extension Agent
MSU Broadwater County Extension Agent |
Weed of the Month: Black Medic
Allison Kosto
MSU Broadwater County Extension Agent
While likely not at the top of the list of the most menacing weeds, the black medic can be a nuisance in certain situations and is worthy of a nomination for weed of the month.
Description & Habitat
Native to Eurasia, black medic was introduced to North America as a forage crop. It is a legume so has the ability to fix nitrogen in the soil. It’s a common lawn weed but can also show up in distributed areas, roadsides, fields and landscape beds. It’s often an indication of low soil nitrogen or nutrients. Black medic can withstand some soil compaction so can also be found along curbs and sidewalks.
Black medic is an annual (life cycle of one year) or a short-lived perennial (life cycle of more than one year). It is often confused with clover. Leaves have three small oval leaflets just like clover. However, the leaves of the black medic have tiny teeth along the leaf edges. Black medic has tiny yellow flowers in small, rounded bunches. The flowers transition into clusters of black fruit at maturity. The stems are covered in tiny hairs, and they creep across the ground creating a mat. Black medic has a deep taproot that is difficult to pull. It reproduces solely by seed.
This plant can be a nuisance by invading lawns and other areas where it is not wanted. It has the ability to form large colonies. It is difficult to control due to its prostrate growing pattern and deep tap root.
Management
The best defense against black medic in your lawn is a healthy lawn. It tends to prefer low nitrogen areas and can grow in compacted soil, so good nutrient management and aeration are key.
As with most annual weeds, the key is to prevent the plant from going to seed. Hand pulling can be highly effective, and the root is more easily pulled when the soil is moist. If the plants are along a driveway or sidewalk, water the area before pulling. Mulch is also an option where practical, at least three inches deep. Since the plant prefers compacted soil, tilling will discourage development but is often not practical where this weed is typically found. Mowing is not effective because the plant grows along the ground.
Herbicides can also be used to control black medic. In lawns, pre-emergent herbicides prior to seed germination can be effective. After the weed is established, then post-emergent herbicides are necessary. Two or three-way herbicide mixes are an effective means to control the plant. Mixtures can include a combination of 2,4-D, dicamba, MCPP or MCPA. Product names include Bushmaster, Chaser, Strike, Super Trimec and Triamine. Chemicals are most effective when applied in late spring to early summer and again in the fall. Always read and follow the entire label when applying herbicide. Common chemical names are used for clarity but does not imply endorsement of a product or brand.
For assistance on weed identification and management, contact the MSU Extension Office in Broadwater County at 406-266-9242.
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PhotoCredit: Photo Credits: Allison Kosto
Image 1 Caption: Black Medic
Photo Credits: Allison Kosto
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