Puncturevine

(Tribulus terrestris L.)

Click on the photo to enlarge (Photo maybe used for non-profit uses with attribution to Mesa County Division of Pest Management).

County Management Strategy: Suppression throughout the County.

Identification: Tap rooted annual weed. Low growing, spreading plants with very small compound leaves arranged similarly to pea plants (legumes). Flowers are yellow, 3/8" in diameter, and shiny, with pointed petals. Seed pods form a "goatshead" with 5 stout sharp spines.

Other names: caltrop, bullhead, tackweed, Mexican sandbur

Similar species: Many other weeds are called goatshead but none have similar seed pods. Similar species include prostrate knotweed, prostrate spurge. Knotweed does not form seed pods. Spurge has milky sap.

Control Timing: As soon as seedlings are noticed, usually in late June or July.

Control Target: Prevent seed production.

Control Methods: Digging, hoeing, tillage in seedling stage. Herbicides before seed set. Biological control agents are available for this species. Status in Mesa County: Common in waste areas, roadsides, driveways, desert trails and disturbed areas in lower elevations of Mesa County. Starting to show up near Mesa and Collbran. Toxicity: Toxic to livestock when consumed in large quantities. Impact: Punctures bicycle tires. Can get stuck in feet of pets, children and adults. Easily spread by all methods of transportation.

Photos:
http://www.invasive.org/weedus/subject.html?sub=3937

Fact sheets and control:
http://www.naturesongs.com/vvplants/puncturevine.html
http://www.ext.colostate.edu/ptlk/2109.html

Additional Links:
http://www.barbwired.com/andy/PunctureVine/