I received many calls this late winter about clover infestation in lawns. Please remember, folks, that your lawn is still dormant and will only actively grow when the soil temperatures reach 70-75 degrees. It may take some time to reach these temperatures.
When your lawn is not actively growing and your soil is not as fertile as it could be, this combination creates a great medium for weed infestation.
I came across a great article written by a master gardener from Galveston County that highlights the biology, management, and control of Bur Clover on the home lawn. Most of the publication is printed below.
“A common clover that grows in this area and is quite invasive is known as Bur Clover. Although not a true clover, two species identified in the area are commonly known as the large bur clover (Medicago polymorpha) and small bur clover (Medicago minima). Both species are dicots (deciduous plants) in the legume family and are closely related to the true shamrocks.
“Big burklee and small burklee are native to Europe, but are brought to the USA as pasture (forage) for cattle.
“Large burklee can grow 6 to 22 inches and has clusters of 3 to 5 flowers that bloom in early spring.
“Little burklee can grow from 6 to 18 inches long, showing 10 or more flowers per head (inflorescence).
“In this region, Bur Clover blooms from February to June but can grow all year round.
“Germination occurs in the fall season when the temperatures are cooler. Bur Clover is easily identified by its small pea-like yellow flower, three green clover-shaped leaves, and purple stems. It reproduces from seeds contained in “deburred” seed pods, as well as from spreading prostate stolons, which allow it to tolerate dense mowing, improve survival, and improve its ability to spread. The exterior of pitted seed pods has numerous Velcro-like hooks that can become entangled in animal coats or human clothing, which is a common means of diffusion.
“Preventive practices like good lawn management are best for reducing infestation. Here on the Gulf Coast, a soil-test-based lawn fertilization program will encourage the growth of a thick, healthy lawn, preventing the clover from becoming established. Mechanical or physical removal is not recommended as stolons can break and sprout, making the infestation more likely to increase than decrease.
“Pre-emergence herbicides, such as those found in weed and fodder fertilizers, can be used to prevent seeds from germinating in the fall. The timing of the application is critical to effective control. Early October is recommended, as cool fronts usually appear during this time and the seeds of weeds begin to germinate in the cool season.
“While weed and fodder fertilizers can be powerful tools for lawns, they can pollute or kill landscaped trees and shrubs if applied under or near your drip line. In spring, over-the-top herbicides or post-emergence herbicides such as “broad-leaf weed killers” can be used.
“If you decide to use a post-emergence herbicide, do so when the burklee is actively growing. Apply a broad-leaved lawn herbicide that contains a combination of 2,4-D and MCPP or triclopyr as active ingredients in late May or early June. More than one application may be required.
“To be most effective, the herbicide should be used when temperatures are between 60 and 80 degrees, no rain is forecast for 24 to 48 hours, and there is no wind to blow the herbicide on desirable deciduous plants.
“If you are targeting small, unwanted spots, you can avoid using a tank sprayer by mixing the herbicide according to the directions on the label and then applying it with a disposable brush or a sponge attached to a pen. Glyphosate works well because the area can be re-sown seven days after application. Note, however, that glyphosate is not selective – it can kill or damage the grass or other green, living plants it touches. Be sure to read and follow the directions and precautions on the product label. “
If you have additional questions, call the Texas A&M Agrilife Extension – Victoria County office at 361-575-4581.
Source: Marian Kimbrough, “Bur Clover,” Texas Master Gardener Association, Galveston County
Matt Bochat is a County Extension Agent – Ag / Natural Resources Victoria County Texas A&M Agrilife Extension.
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