Puncture vine is a noxious weed sometimes called "goat head." It's most commonly found in eastern Colorado at elevations below 6,500 feet, in disturbed soils and vacant lots. It's a low-growing, mat-forming plant with small leaflets and one-half inch wide yellow flowers. Trailing stems may reach one to six feet long in the summer. Hard spiny burs about one-half inch wide develop after flowering. These burs, which can easily puncture bicycle tires or a gardener's skin, contain seeds.
Puncture vine plants can be controlled by pulling them out of moist soil but be sure to wear gloves to protect your hands from the prickly fruits. Mulch, when applied thickly enough to block light to the ground, can be effective at reducing populations. There are two types of weevils available for control from the Colorado Insectary in Palisade one feeds on the seed and one on the stem.
Herbicides can also provide effective control if they're applied when the plants are young and small. Certain pre-emergent herbicides, applied around April 1st, can kill puncture vine seedlings as they germinate. However, pre-emergent herbicides may have to be used each April for several years to achieve good control, because puncture vine seeds can remain viable in the soil for many years.
If you decide to use herbicides, be sure the herbicide product you chose is labeled for control of puncture vine, and, as with any pesticide, read and follow label directions explicitly.
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Updated Thursday, February 18, 2016