Puncturevine (Tribulus terrestris L.), native to Europe, was introduced into the United States with livestock imported from southern Europe. Puncturevine is also called goatshead, bullhead, caltrop, Mexican sandbur and devil’s thorn. Puncturevine is most often found in sandy, dry, or gravely soils. Puncturevine is a warm season prostrate annual that forms dense mats up to 8 feet across. The leaves are one to three inches long, pubescent, opposite, have short petioles and divided into pinnate leaflets; each leaflet is about 1/4 inch long. Puncturevine flowers are cross-pollinated by insects. Puncturevine reproduces completely by seeds. Seeds germinate in late spring and early summer under suitably moist conditions. A single plant can produce from 200 to 5000 seeds during one growing season. Seeds may remain viable in the soil for five or more years. Puncturevine produces sharply pointed woody burs that can be spread by equipment, the feet of animals, the soles of shoes and tires.

                     
                   Flower                                          Seed/Bur                                 Plant Spread   
Effects on animals: If grazing animals happen to eat a bur, it may cause injury to the mouth, stomach, and intestines. Generally puncturevine is not grazed, but if it is, it can be toxic. Puncturevine can be particularly toxic to sheep, causing sensitivity to light resulting in skin lesions and swelling of the ears and lips. Severe effects include blindness, necrosis of skin, loss of lips and ears, and death in young animals. Puncturevine may also contribute to nitrate poisoning in sheep and cattle.

Uses: In Europe the plant has been used in folk medicine throughout history, treating such wide-ranging conditions as headache, nervous disorders, constipation, and sexual dysfunction. In China, it has been regarded as a remedy for liver, kidney, urinary, and cardiovascular disorders.

Control:

Chemical: Imazapyr (Arsenal) and imazapyr plus diuron (Sahara) can provide excellent control. Picloram, applied as a pre-emergence spray, can give some control. The spraying of young plants with glyphosate, dicamba, amitrole, chlorsulfuron, diuron, hexazinone, or 2,4-D may also be desirable.

Refer to the label for all herbicides
Always follow label directions prior to use

Cultural Methods: Repeated cultivation just after germination is an effective control. If burrs are produced before cultivation, it is necessary to remove the plants and burrs and burn them.

Biological: Two weevils, Microlarinus lareynii and M. lypriformis, native to India, France, and Italy, were introduced into the United States in 1961 as biological control agents. The larvae attack the seed and stems and have given reasonably good control in some regions. It is recommended that a minimum of 250 adults be released per acre on puncturevine in moderate infestations. For major infestations, release rates of up to 500 adults per acre may be appropriate.

Microlarinus lareynii deposits its eggs in the immature seed (burr) and the larvae feed on the seeds. Females may deposit up to 324 eggs; however, each seed may only have 1-3 weevils. At this time, M. lareynii has failed to establish in Washington. Microlarinus lypriformis lays its eggs on the undersides of stems, branches, and in the root crown. The larvae then burrow in the stems on the plant.

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Questions: contact Steve Van Vleet or phone (509) 397-6290