Learn More About Burr Medic And Its Control

Learn More About Burr Medic And Its Control

By: Nikki Tilley, Author of The Bulb-o-licious Garden

If your lawn is filled with prickly burrs, you likely have burr weeds. Read on to learn more.

What is Burr Medic?

Burr medic (Medicago polymorpha), also known as burr weed, is a type of trifoliate weed that can quickly spread throughout the lawn and garden if not controlled.

You can recognize this weed by its green serrated leaves and reddish purple colored stems that creep closely along the ground. It also has small yellow flowers. After flowering, the tiny green pods produce prickly burrs. These will eventually dry up and turn brown, spreading seeds everywhere.

Burr medic germinates in fall and winter, and flowers in spring.

Types of Burr Weeds

There are several types of burr weeds, most of which can be found growing in a wide range of conditions and soil types. However, burr medic seems to favor poor soils, such as heavy clay. Like other trifoliate weeds, such as clover, burr weed has leaves that are grouped together in threes.

Other burr species include:

  • Woolly medic (M. minima)
  • Spotted burr medic (M. arabica)
  • Barrel medic (M. truncatula)
  • Cut-leaved medic (M. laciniata)

How to Kill Burr Medic

Since burr medic spreads and reproduces by seed, the best way to control the weed is to remove it before it has a chance to set its seed, even better before it flowers.

While burr medic can be controlled with regular mowing, this will not kill the weed. It is also tolerant of most herbicides, though non-selective types can help kill the plant as well as boiling water. Neither of these, however, will kill the burrs that are left behind in the lawn or garden.

Therefore, you may want to use an old woolen blanket to drag over the area first, which should snag most of these burrs. Then the area can be treated with a pre-emergent, such as corn gluten meal, to prevent germination of any seeds left behind. Late summer or early fall is a good time to do this.

The use of broadleaf post-emergent weed killer, like Weed-B-Gone, prior to flowering (winter/early spring) can help as well.

Once burr medic has been eradicated, you’ll want to improve the health of your soil to minimize its return by amending it with organic matter or compost.

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

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Controlling Lawn Burweed: The Spring Lawn “Sticker”

Most lawn weeds are annoying, appearing in unwanted places and numbers, but few actually cause physical harm like the pest plant Lawn Burweed (Soliva sessilis)! This infamous small, spreading winter weed’s seeds generally germinate when temperatures begin to cool in the fall (late October-November). Burweed then grows mostly unnoticed through the winter until spring, when it then produces the hard, spiny burs that contain the plant’s seeds and the plants finally die. Once the burs have formed, Burweed’s presence makes walking on newly greened-up spring turf extremely painful for pets and people (barefoot of course, the burs aren’t large enough to puncture shoe soles). At this point of the plant’s life, once it has made its unwanted presence known, control is not feasible as the Burweed plants have set seed, ensuring a new crop next year, and killing the remaining foliage doesn’t remove the burs. What is a homeowner to do?

Newly germinated Lawn Burweed. Photo courtesy of the author.

Fortunately, Lawn Burweed is relatively easy to control chemically if one pays close attention to seasonal changes and uses herbicides (either pre-emergent or post-emergent herbicides) effectively.

Pre-emergent Herbicide Options: The first chemical control option for Lawn Burweed is a timely application of the pre-emergent herbicide Isoxaben (sold under various brand names at most farm or garden stores) to prevent Burweed seeds from germinating, greatly reducing plant populations. However, pre-emergent Isoxaben applications must be made before the plants sprout and begin to grow to be effective. For Burweed, this generally means application in October, once nighttime temperatures dip into the 55-60 degrees F range for several nights in a row, as consistent temperatures in this range give Burweed seeds the signal to germinate. Though we’re already past the point of pre-emergent herbicides being an option for control this year, homeowners should plan to include this method in their Lawn Burweed control plan for fall 2020!

Post-Emergent Herbicide Options: If you haven’t already used a pre-emergent herbicide this fall for Burweed control, you must turn to post-emergent options. Like pre-emergent herbicides, timing is critical if you want your post-emergent applications to work! These herbicides are most effective when Burweed plants are young, small, vigorously growing, and haven’t set burs yet. Successful post-emergent applications may be made from December-early February before burs harden. Unlike pre-emergents, where there is only one strong option for Burweed control, many post-emergent herbicides exist that are extremely effective! When shopping, look for products containing the following active ingredients:

Lawn Burweed around 10 days after emergence. Photo courtesy of author.

  • Atrazine – sold under many brand names and safe in Centipede, St. Augustine, & Bermudagrass. Do not use in Zoysia or Bahiagrass lawns.
  • Dicamba, Mecoprop, 2,4-D – commonly sold in three-way formulations through many brand names. Generally safe in Centipede, St. Augustine, Bermuda, Zoysia, & Bahiagrass lawns.
  • Metsulfuron – sold under several brand names and safe in Centipede, St. Augustine, Zoysia & Bermudagrass. Do not use in Bahiagrass. Be careful if used around ornamentals.
  • Thiencarbazone, iodosulfuron, dicamba – sold as Celsius WG from Bayer. Safe in Centipedegrass, Zoysiagrass, Bermudagrass, and St. Augustinegrass. Do not use in Bahiagrass.

Lawn Burweed control with of all the above-listed herbicides will be most effective with a follow-up application 10-14 days later.

Note: With the exception of the Thiencarbazone, iodosulfuron & dicamba mixture (Celsius), do not apply any of these post-emergent herbicides during spring turf green up.


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.

  1. 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.
  2. 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.


What Is Burr Medic And How To Kill Burr Medic - garden

Burr Medic
Medicago polymorpha L.

Synonyms - Medicago hispida Gaertn., Medicago denticulata.

Medic is from the Latin medica meaning Lucerne and derived from the Greek mediche because it was introduced to Greece from the Media region in the Old Persian Empire.
Burr Medic because it has obvious burrs.

Burr Clover
California Burr Clover
Creeping Burr
Medic Burr
Medic Clover
Rough Medic
Toothed Burr Clover
Toothed Burr Medic
Toothed Medic
Trefoil

Burr Medic is a low-growing, almost hairless, sprawling herb with leaves divided into 3 heart-shaped leaflets each 4-25 mm long. The terminal leaflet is on a longer stalk than the two side leaflets. It has clusters of 2-7, small, yellow, pea-type flowers with petals that are only 3-5 mm long. The fruit is a small, greenish-brown burr with 1-6 tight coils that are often spiny.
Native to the Mediterranean region, Burr Medic is a common weed of gardens, pastures and roadsides and flowers in winter and spring.

Two. Oval. Tip round. Sides convex. Base tapered to squarish. Surface hairless. No petiole.

The first leaf is kidney shaped, 10-20 mm long. Stalked. Tip and base indented. Hairless. Later leaves have 3 leaflets.

Alternate. Three leaflets on the end of a long leaf stalk. Stalk of the middle leaflet is longer than the outside ones.
Stipules - Leafy, narrowly egg shaped, finely to deeply toothed, outgrowth 4-10 mm long at base and attached to the petiole. Tapers to a pointed tip.
Petiole - Long and hairless.
Blade - Of leaflet, oval to heart or wedge shaped, 5-25 long x 4-17 mm wide, toothed near tip, smooth edged near the base. Tip occasionally blunt but usually notched and the midrib sticks out to form a small spine. Always hairless on the upper surface and hairless or occasionally with sparse hairs on the lower surface.

Prostrate or upward bending at the ends, square, branched from base, 200-1000 mm long. Hairless.

Axillary raceme, 4-6 mm long, with clusters of 2-10 flowers on stalks, 5-20 mm long that may have a terminal awn.

Pea type, yellow, small, 3-6 mm long.
Bracts - Small, persistent.
Ovary -
Calyx - Tubular with 5 lobes. Tube 1-2.5 mm long. Lobes 1-3 mm long, triangular to awl shaped.
Petals - Yellow. Standard 3-5 mm long x 2.5 mm wide, with an egg shaped limb. Wing 3 mm long. Keel 2-2.5 mm long
Stamens - 9 in a group and 1 alone.
Anthers -

Green-brown to black, hairless, flattened pod coiled into a disc shaped or cylindrical burr with 1.5 to 6 loose coils, 2-12 mm long x 3-8 mm diameter (without spines).Spines 2-4 mm long, spreading, curved or slightly hooked and often soft when mature. Occasionally spineless or warty. Valves have an obvious network pattern on the surface especially near the ends. Seam on the back of the pod is narrow with a furrow between it an each of the 2 parallel side veins. Pod usually has 3-6 seeds.

Brown, kidney shaped, 2-4 mm long, 1-2 seeds per coil of the pod.

Taproot. Have nitrogen fixing nodules.

Cotyledons oval shaped.
First leaf kidney shaped.
Older leaves trifoliate with the terminal leaflet on a longer petiolule than the side leaflets.
Square, hairless stems.
Yellow pea type flowers.
Disk shaped to cylindrical burr with 1.5 to 6 loose coils. Hooked, slender spines that are grooved near their base and 2-4 mm long. Network pattern on valves. Transverse nerves terminating in a nerve parallel to and on each side of the dorsal suture. Obvious furrows parallel to the dorsal suture on the pod. Peduncles are a similar length to the leaflet.
Kidney shaped seed.
Annual.

Annual. Germinates in autumn to winter and produces large amounts of palatable herbage in winter and spring. Flowers in spring and dies with the onset of summer drought and high temperatures.

Prefers high phosphate levels.
Can set seed in short growing season years.

Spring in western NSW.
July to December in SA.
July to October in Perth.
Winter to spring in WA.

Seed Biology and Germination:

Produces hard or dormant seed.
Germinates from autumn to spring (Kloot, 1980).

Vegetative Propagules:

Several varieties exist including var. vulgaris.
Some varieties have no spines or spines reduced to warts on the burr.
Var. brevispina has no spines.

Population Dynamics and Dispersal:

Mainly spread by burrs attaching to passing animals to distribute seed.

ACT, NSW, NT, QLD, SA, TAS, VIC, WA.

Courtesy Australia's Virtual Herbarium.

More abundant on heavy alkaline soils. Grows on a wide range of soils

In a range of communities from open grasslands to woodlands.

Important pasture species especially on the heavy alkaline soils.
Produces good quantities of palatable fodder over the winter to spring period.
Burrs provide a protein supplement over summer.
Fixes nitrogen.
Honey plant.

Weed of crops, gardens, lawns, recreational areas and disturbed areas.
Causes vegetable fault in wool.

Occasionally toxic causing photo sensitisation referred to as trefoil dermatitis, clover sickness or trifoliosis in sheep, cattle horses and pigs. Lambs including newly born ones are most affected. Mainly occurs on luxuriant growth during sunny weather in spring. May cause bloat in cattle.

Dermatitis with no jaundice. Rarely fatal.
Bloat

Remove stock from infestation.

Management and Control:

In cropping situations, 10-40 plants/m 2 are often worth controlling.

Eradication strategies:

Exclude stock to reduce dispersal of burrs.
Hand pull isolated plants in winter before flowering. For small infestations and grass dominant areas an annual application of 10 mL Tordon®75-D in 10 L water in early winter gives excellent control of existing plants and has residual activity to control later seedlings. In bushland, 25 mL of wetting agent plus 4 g of Lontrel®750 or 1 g of Logran® in 10 L water applied in early winter provides reasonably selective control. Metsulfuron(600g/kg) at 10 g/ha also provides good control but is less selective. Repeat annually for several years.
Plant tall growing perennial species to reduce re-invasion. It is relatively tolerant to glyphosate, grazing and mowing.

It is relatively tolerant to glyphosate.

Barrel Medic. (M. truncatula)
Black Medic (M. lupulina)
Burr Medic (M. polymorpha)
Button Medic (M. orbicularis)
Calvary Medic (M. intertexta)
Cutleaf Medic (M. laciniata)
Disc Medic (M. tornata)
Gama Medic (M. rugosa)
Lucerne (M. falcata ssp. sativa)
Lucerne (M. sativa)
Small leaved Burr Medic (M. praecox)
Snail Medic (M. scutellata)
Spotted Medic (M. arabica)
Strand Medic (M. littoralis)
Woolly Burr Medic(M. minima)
Yellow Lucerne (M. falcata)

Plants of similar appearance:

Clovers (Trifolium species) usually have the central leaflet on a stalk the same length as the side leaflets.
Melilotus species
Oxalis species usually have a bitter taste.
Trefoils
It differs from native species which have leaves divided into 3 leaflets such as Gompholobium and Kennedia and in its flower and fruit characters.
Gompholobium marginatum has similar leaves but a loose cluster of few larger flowers and a stalked, somewhat brittle, broad pod.
Kennedia species usually have much larger leaflets and have much larger pink to red or orange flowers and a cylindric pod.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P459. Diagrams.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P223. Diagram.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P402-3. Photo.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P470-471.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P154. Photo.

Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P104-105. Diagram.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #806.12.


Effects of Concentrated Vinegar

As well as controlling weeds and grass in yards, concentrated vinegar can have some undesirable effects. Concentrated vinegar corrodes concrete, iron, tin and aluminum. What's more, there's a danger of accidentally spraying hidden wildlife and beneficial insects when treating weeds and grass. The acid would have a disastrous effect on these organisms. Finally, if concentrated vinegar is poured onto the soil, it raises the pH, making it difficult for other plants to grow in the spot. When spraying, direct the vinegar so it hits only the weeds you wish to remove.


Weed Chart

We’ve put together a list of the most common weeds in lawns. Knowing what you have to kill is the first step in getting your lawn back in shape. We hope this guide helps you do just that!

Produces painful prickles. Easy to kill if treated at the right time. Mid August to late October is best but no later as the seed burrs will develop. Use Bindii specific herbicide.

Can be quite common but easy to eradicate with broadleaf weed killer. Regular mowing stops it from producing flowers and then reseeding.

Rarely issue in healthy lawns as prefer sparse areas in turf and gardens. Cannot re-grow after leafy part removed so regular mowing or hoeing will control.

Very difficult to eradicate as it multiplies by seed very quickly in summer. Deal with as soon as noticed. Maintaining a healthy lawn is best way to reduce infestations.

One of the most common of weeds in lawn. Easy to eradicate with a broadleaf weed killer. If only a few, pull out by hand but ensure to get taproot as well.

Can be major problem in lawns as grows from tiny corms which continue to multiply. Paint with glyphosate to eradicate. May need 2-3 applications.

Commonly emerge in areas that rarely disturbed. Easily pulled out by hand or spot sprayed with glyphosate. Avoid allowing seed heads to form.

Quickly spreads throughout garden by seeds so it is important to eradicate before prickles form and seeds set. Can be hand weeded or sprayed with clover killer.

Broadleaf weed that is easy to control. Similar to dandelion but with hairy leaves. Can be pulled out by hand or controlled with broadleaf weed killer.

Can be an eyesore in lawn and can smother entire areas if left unchecked. Often sign of low nitrogen in soil so fertilise area. Easy to control with clover specific herbicide.

Often mistaken for clover but this weed is more aggressive. Use herbicide for clover but may need 2-3 treatments. Use glyphosate if weeds in garden beds.

Summer grower with a couch like runner system. It can be difficult to kill so 2-3 treatments may be necessary. Paint with glyphosate.

All fleabanes produce lots of seeds so pull out or treat whilst young. Spot treat with glyphosate. If large and woody, the best option is to remove by hand.

Germinates in May-June. Must be tackled early as once established is difficult to treat. Use product designed for Winter Grass. After heavy infestations, consider aerating lawn.


XL 2G Granules - Questions & Answers

XL 2G Granules are safe to use on tall fescue and warm season grasses such as bahiagrass, bermudagrass, buffalograss, centipedegrass, St Augustinegrass and zoysiagrass.

XL 2G Granules - 50 lb. bag coverage varies on the application rate you are using. You will use 4.6 - 6.9 lbs. per 1,000 sq.ft. At most one bag will cover 11000 sq feet.

The product label (instructions) for XL 2G Granules can be found here: http://www.domyownpestcontrol.com/msds/xl%202g.pdf

Per the XL 2G product label, reseeding should be delayed by 8 weeks when using the 100 lb/acre rate or 12-16 weeks when using the 150 lb/acre.

XL 2G is safe to apply to established tall fescue, bahiagrass, bermudagrass, buffalograss, centipedegrass, st. augustinegrass, and zoysiagrass. However, XL 2G should NOT be used around plants or trees that will bear fruits, berries, or nuts within 12 months of application.


Watch the video: How to Kill Sticker Burr Weeds