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black medic weed seeds

Black Medic Weed Identification (+ how to kill it in lawns)

When you’ve worked hard to cultivate the perfect lawn there’s nothing worse than an unsightly weed creeping into your yard. Most common weeds can be easily identified. But there are some, like Black Medic, that blend right in and disguise themselves as something more common. In today’s article I will be discussing everything you need to know about Black Medic weed. I’ll explain what it is, how to identify Black Medic, why it may be a threat to your lawn, and most importantly – how to get rid of Black Medic weeds on your property.

Let’s start with the basics.

What is Black Medic Weed?

Black Medic weed (Medicago lupulina) is a noxious weed that is also commonly known by different names such as Yellow Trefoil or Yellow Clover. It is a weed that is often confused and mis-identified as clover with yellow flowers. But there are some key differences between Black Medic and the common clover varieties you may be familiar with.

A noxious weed is one that is harmful to its environment and the animals around it. Since Black Medic qualifies as this type of weed, it is imperative to keep Black Medic under control.

Black Medic weeds are fast spreading, low growing weeds that can blend into your lawn if you don’t know what to look for.

So let’s dig into how to identify Black Medic.

What Does Black Medic Weed Look Like?

At first glance, Black Medic looks like a clover. This is why it often goes undetected and untreated by homeowners who understand the benefits of clover in their yard.

So now the big question is, how do you tell them apart? Let’s compare Black Medic to Clover.

The biggest difference between Black Medic and Clover is that the Black Medic weed often sprouts small, yellow flowers. If you take a closer look at the patterns on the leaflets, you will also notice that the middle leaflet has a short stock, while the others hang more laterally towards the stem.

Now, if you look at the shape of the leaflets, you can see that the edges of the Black Medic weed’s leaves are sharper and have-tooth like edges.

When clover flowers it will be white, or a shade ranging from pink to purple, to crimson.

Where Does Black Medic Weed Grow?

Black medic grows in grasslands and other areas that are typically undisturbed.

It can be found all throughout North America, except for desert areas. But it is native to Europe as well as warmer parts of Asia.

This weed typically takes root in soil that is tightly packed with poor nitrogen quality. If you discover it in your yard, you may want to perform a soil test on your lawn. This will allow you to better understand what nutrients your lawn needs to thrive.

Is Black Medic a Perennial or Annual Weed?

Black Medic is a summer annual weed. Unlike perennial weeds that return year-after-year, summer annual weeds sprout during the summer and die off by the time there is a change in seasonal temperature.

Summer annual weeds spread only by seed, unlike perennials which spread through both seed, rhizome, or stolon.

How to Get Rid of Black Medic In Your Lawn or Garden?

After identifying Black Medic, it is imperative to get rid of it as soon as you can.

There are a few different ways to kill Black Medic, and today I’ll discuss both natural / organic methods, and chemical methods such as herbicides.

Everyone has different mindsets about using chemicals to eliminate weeds, so I want to provide you with the best options either way.

Natural and Organic Methods

Unlike using herbicides to kill Black Medic weed, natural and organic weed control methods are able to focus on the root issue without affecting the surrounding area.

Natural and organic control will allow you to get rid of Black Medic weed through either soil control or hand weeding. Each is a bit more labor-intensive than using herbicides that kill Black Medic weed.

  • Soil Control- Also commonly known as cultural control, this approach deals with the soil quality of your lawn as a remedy for Black Medic Weed. It is important to understand that Black Medic weed only grows in compact soil. Lawn aeration in the fall can be an easy fix, and overseeding that section of your yard at the same time to thicken up your turf is a good preventative measure that will help prevent Black Medic from germinating the following spring.
  • Hand Weeding – This method for controlling Black Medic refers to good old fashioned weed extraction. It’s best to pick out the weeds from the soil when your yard is wet. Since it’s an annual weed, this also means that elimination will be easier since they only spread through seeds and not other parts of the weed. When you pull the weeds, bag them – don’t just leave them sitting on your lawn. Black medic tends to grow together in a central location, this could mean that controlling it and getting rid of it is much easier than some other types of weeds. Personally, I find that this is one of the easiest weeds to pull by hand.

Best Herbicides to Kill Black Medic

Herbicides are liquid solutions meant specifically for getting rid of unwanted weeds in your lawn or garden.

There are a variety of different herbicides on the market to deal specifically with Black Medic. If you want to take a more natural approach there are also some DIY at home solutions that can get the job done.

Be mindful that it is always a good idea to test for effectiveness in a small area to ensure the herbicide will not damage other areas of your lawn while killing this frustrating annual weed.

I also always recommend that you wear proper PPE when spraying herbicides.

Post-Emergent Herbicides to Kill Established Black Medic in Lawn

Post-Emergent Herbicides are used after the weed has already sprouted and taken root in your lawn. They can be store bought or homemade according to your preference.

My Recommended Herbicide for Black Medic

There are many different brands of herbicides that will be effective against Black Medic weed, and the one you end up choosing for your lawn may come down to availability.

Many of the herbicides at your local box store or hardware store that are labeled for selective broadleaf weed control may work against this weed.

Key ingredients to look out for when shopping include triclopyr, dicamba, and clopyralid which are the active ingredients that effectively kill Black Medic.

Personally, I’ve had the best success with T-Zone from ITS Supply. It’s a selective turf herbicide that won’t touch most lawn grasses, but is very effective against Black Medic. You can purchase it on Amazon.

DIY Herbicide for Black Medic

If you want to make your own herbicide, then spraying vinegar will usually work. A 20% vinegar solution will burn through the leaves of most plants and kill growth, but this may not kill the plant to its root.

Since Black Medic is an annual, and you only really need to suppress growth until it dies back in the winter, this can be an effective strategy for small infestations.

But bear in mind … something like this will also kill any grass it comes into contact with, which is why most people prefer hand-pulling Black Medic, or using T-Zone so that your lawn will be undamaged.

Pre-Emergent Herbicides to Keep Black Medic From Coming Back

Pre-Emergent herbicides are a great way to prevent Black Medic from returning every spring.

Black Medic is a summer annual weed. This means its germination period is usually in late spring before it starts to warm up.

Applying the pre-emergent to your lawn that has been aerated the prior season should get the job done, as these products block seed germination for 3-5 months.

Lawn Care Habits That Can Keep Your Lawn Free of Weeds

Like most weeds, Black Medic Weed attacks lawns with weak soil quality and under-competing grass.

Some of the best remedies include healthy lawn habits such as:

  • Healthy soil: Black medic has the opportunity to grow in compact, dry soil. Taking an aerator to your turf, and supplying adequate water is a good prevention method. It’s also a good lawn care practice in general.
  • Over-seeding: While the soil may not be compact, you can fill in patchy areas of your lawn with extra seeds every year. This rejuvenating lawn care practice keeps your lawn healthy and dense.
  • Mowing routines: mowing your grass prematurely or too low slows down its growth. This will allow weeds to out compete your grass. Make sure to mow at the proper height for your grass.
  • Lawn mower maintenance: dull blades on your lawn mower could be pulling your grass rather than cutting it. This disrupts its growth cycle and weakens the soil quality in your lawn. Routine lawn mower check ups are a good way to make sure that the blades are kept sharp.

Final Thoughts About Controlling Black Medic Weed

In short, you’ll deal with Black Medic weed how you would handle any other weed infestation problem in your lawn.

Once you identify the weed, a course of action that includes removal and then prevention will work.

Like most issues that homeowners have with their lawn, it’s easier to prevent a problem than treat it.

Keeping up with your lawn maintenance, and providing regular feedings to your turf is essential. Doing so will help maintain a thick, strong, and healthy lawn. This leaves no room for weeds to germinate and grow.

Like I always say – the best defense against weeds is a good offense!

I hope that the Black Medic weed information, prevention tips, and control methods I’ve outlined help you out. Best of luck as you kick this pesky weed out of your yard once and for all!

Black Medic, Medicago lupulina

Confirm the presence of black medic before you treat.

Where to find it while inspecting: Found in turf and disturbed soils that tend to be dry and nutrient deficient.

2. Proper ID

Is it black medic?

Size and Appearance: Spreading, low stems, branched at base. Leaves are alternate, three to a stem and resemble lawn clover and woodsorrel, (smaller leaflets vary in shape and size), bright yellow flowers with dense flower heads.

3. Learn the Pest Biology

What is the life cycle of black medic?

Life Cycle: Summer annual, reproduces by seed which germinate in spring or fall. Flowers and seed production continue all summer. Yellow flowers eventually become black seedpods when mature.

Preferred habitat: Grows well in dry soil, soil low in nitrogen, compacted soil.

4. Determine Threshold

How much black medic is too much?

Threshold: Because it produces a few thousand seeds in a season, and flower heads grow low to the ground, it is difficult to control once established. Act promptly when you find this plant.

5. Choose Tactics

Creating a healthy soil condition and understanding turfgrass’s needs is the first step in reducing turf pests. What can I do to treat, reduce, or prevent black medic?

Best Management Practices: Black medic can often be removed by hand when soil is moist. Reduce compaction by use of aeration. Give your turfgrass chance to succeed: maintain proper soil pH: 6.0 to 6.8 (test every 3–5 years). Fertilize at the proper time for turfgrass root development, primarily fall (late spring at times when turf is weak and thin), irrigate if needed, mow at proper height (removing no more than 1/2 of the blade), amend poor soil, choose proper turfgrass seed for your conditions, buy quality seed, overseed thin spots in fall or early spring, remove thatch. Remove small patches of black medic by hand-weeding when soil is moist or digging out. Aerate soil to help turfgrass and reduce compaction. Mow at higher end of mowing tolerance range for turfgrass species and cultivars when possible to shade out germinating seeds. In Gardens: does not thrive in shade, so mulch reduces germination and new growth.

Treatment Methods: Black medic will not thrive where turfgrass is given proper moisture and soil is aerated. Where these actions can not succeed, and manual removal is not an option, you may choose to use a herbicide where allowed by law; a general broadleaf herbicide in spot applications.

6. Evaluate

Was the tactic successful? Record the date pests were first noted, and the tactic you used, and its success. Use one of our RECORD KEEPING tools.

For More Information:

Remember:

When a pesticide application is necessary, all necessary and required precautions are taken to minimize risk to people and the environment and to minimize risk of pesticide resistance or pest resurgence. Pesticide use in your school may be prohibited or regulated by local policies or state and federal regulations. Risk reduction methods can include, but are not limited to, spot-treatment, the use of gel or paste bait formulations placed in inaccessible locations, injection into a crack or crevice, and other methods that reduce potential exposure.

This site was produced by the New York State IPM Program of Cornell University, with funding from a Northeastern IPM Center Partnership Grant, in collaboration with the School IPM Working Group. Content reviewed and updated: February 2020.

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Regional IPM Centers are sponsored by the USDA National Institute of Food and Agriculture.