PUNCTUREVINE Integrated Pest Management for Home Gardeners and Landscape Professionals Puncturevine (Tribulus terrestris) is an stick into passing animals aptly named summer annual found and tires. These burrs widely in California. Native to south- disperse by adhering to ern Europe, it can grow under a wide tires, shoes and clothing of range of conditions, but its success is people, and the fur, feathers, likely due to its ability to thrive in hot or feet of animals. and dry conditions where other plants Puncturevine germinates cannot. It can be a major problem in in the spring and summer orchards, pastures, turf, and along from seeds produced the roadsides and ditch banks. Although it previous year. Good soil is known to be toxic to sheep, its main moisture and warm tem- weedy characteristic, as indicated by its peratures are needed for common names of puncturevine or cal- germination, but after the trop, is its spiky seedpods. (A caltrop plant is established it can is a metal device, used to deter passage tolerate dry soils due to by vehicles with pneumatic tires or the its rapidly produced deep hooves of horses; it has four projecting taproot. The plant may spikes so arranged that when three start flowering within 3 of the spikes are on the ground, the weeks of germination and fourth points upward to poke a tire or flowering will continue hoof.) The seeds of puncturevine are throughout the summer. enclosed in a hard caltrop-like case that Seeds are primarily dor- can injure livestock, people, and pets mant in the first season, when stepped on and can even punc- but may germinate the Figure 1. Puncturevine (Tribulus terrestris). Prostrate ture bicycle tires. Another common next spring. Seeds may plant with flowers and fruits, or burrs. name is “goathead.” remain viable in the A. Single burr containing 2-5 seeds, B. Fruit or soil for up to five years. seedpod, C. Flower. IDENTIFICATION Puncturevine plants can- When allowed to grow unchecked, AND LIFE CYCLE not tolerate freezing temperatures. Puncturevine is a summer annual puncturevine will develop into a thick broadleaf weed that generally grows IMPACT mat, hiding the sharp burrs. Even un- low to the ground forming dense mats A typical puncturevine plant will der limited growth conditions, punc- 2 to 5 feet in diameter (Fig. 1). The produce 200 to 5,000 seeds during turevine’s prolific production of the seed stems radiate out from a central point one growing season, depending on burrs creates dangerous conditions for at the taproot. The plant does not root available soil moisture and other en- livestock, people, and pets. from the stems. The hairy leaves are vironmental factors. These seeds and opposite each other and divided into those that did not germinate from Grazing livestock in areas infested four to eight pairs of leaflets that are previous seasons will contribute to with puncturevine is not recommend- also opposite each other. Yellow flow- the potential weed population the ed. The sharp spines of the seed burr ers up to ½ inch wide with five petals following year. can injure the mouth and digestive are found in the leaf axils. After the tract or feet of animals. Puncturevine flower is pollinated, a seedpod forms With its deep taproot, puncturevine can be particularly toxic to sheep, that is a cluster of five flat spiny burrs competes aggressively for water and causing sensitivity to light resulting in containing up to five seeds. As the nutrients in tree and field crops and skin lesions and swelling of ears and seedpod matures, it turns gray or tan, turf. Puncturevine in hay will mark- lips. Severe effects include blindness, gets very hard and breaks apart so that edly reduce the quality of the product. necrosis of skin, loss of lips and ears, the individual spikes, or burrs, can and death in young animals. Addition- PEST NOTES Publication 74128 University of California Agriculture and Natural Resources March 2006 March 2006 Puncturevine ally, puncturevine may contribute to Mulches can be used to control com- most California counties where releases nitrate poisoning in sheep and cattle. mon puncturevine in ornamental would be beneficial, county agricultural Symptoms of nitrate poisoning include plantings, orchards, vineyards, vege- commissioners have release programs or labored breathing, staggering, tongue table crops, and gardens, if they screen can direct you to collection sites where and the white of the eyes turning blue, out all light. To be effective, organic you may be able to collect them yourself. and loss of appetite. mulches should be at least 3 inches Contact your county agricultural com- thick. However, puncturevine burrs missioner’s office for more information. MANAGEMENT that fall onto mulch surfaces can es- Long-term control of puncturevine can tablish on the mulch surface due to the Chemical Control be achieved by reducing the amount puncturevine’s deep taproot. Synthetic Chemical control is generally not nec- of seeds in the soil. This is best accom- mulches, which screen out light and essary for the control of puncturevine plished by removing plants before they provide a physical barrier to seedling in the home landscape. However, in produce seeds (i.e., before or at flower- development, also work well. large areas, or places where there was ing) and continuing to do so over sever- a heavy infestation in previous years al years. Burrs that have dropped after Aeration of compacted sites and plant- so that it’s difficult to remove by hand, removing the plant may be collected ing competitive desirable plants can hoeing, or tilling, herbicides may be and removed by sweeping or raking also reduce the impact of puncturevine used to control puncturevine. the ground. Even patting the ground by making the area more favorable for with a piece of carpet will help collect the growth of the desired plants and re- There are few preemergent herbicides the burrs. Biological control from two ducing resources available to the weed. that are effective. Products containing introduced weevils is also very ef- oryzalin, benefin, or trifluralin will fective, but there may be resurgences Biological Control provide partial control of germinating every few years as the number of the Two weevils, Microlarinus lareynii and seeds. These must be applied prior to weevils decline along with the popula- M. lypriformis, native to India, France, germination (late winter to midspring). tion of the puncturevine. and Italy, were introduced into the United States as biocontrol agents After plants have emerged from the The primary method of manage- in 1961. Microlarinus lareynii is a seed soil (postemergent), products contain- ment for puncturevine in the home weevil that deposits its eggs in the ing 2,4-D, glyphosate, and dicamba landscape and garden is removal of immature burr or flower bud and the are effective on puncturevine. The seedlings and older plants by hand larvae feed on and destroy the seeds smaller or younger the plant, the bet- or hoeing, taking care to also remove before they pupate and emerge as ter the postemergent herbicides work. any burrs that fall off the plant. Avoid adults, disperse, and start the cycle Dicamba and 2,4-D will injure most bringing puncturevine into uninfested over again. Generation time is 19 to broadleaf plants so it is important that areas on shoes and the wheels of mow- 24 days in the summer in southern they only be applied to the weeds and ers or carts. California. Microlarinus lypriformis is drift is minimized. They can be applied a stem weevil that has a similar life to lawns without injuring the desired Cultural cycle except that it lays its eggs in the grass. Glyphosate will kill or injure and Mechanical Control undersides of stems, branches, and most plants so it should only be used In most situations, puncturevine is the root crown. The larvae tunnel in as spot treatments or on solid stands of best controlled by hand removal or by the pith where they feed and pupate. the weed. hoeing to cut the plant off at its taproot. The adults emerge from holes chewed REFERENCES Monitoring the area and removing the in the upper surfaces of the stems, Anonymous. The American Heritage weed throughout the late spring and branches, and crowns. Adults of both Dictionary of the English Language. 2000. into the summer will greatly reduce species overwinter in plant debris. Houghton Mifflin Company. the impact of the weed the next year. Although the stem weevil is slightly Shallow tilling (about 1 inch deep) of more effective than the seed weevil California Department of Food and seedlings or small plants can be effec- when each is used alone, the weevils Agriculture. Tribulus terrestris. Encyclo- tive in larger areas. Deeper tilling is are most effective if used together and weedia. Available online, http://www. not recommended since this may bury the puncturevine is moisture-stressed. cdfa.ca.gov/phpps/ipc/weedinfo/tribu- seeds and they may be able to germi- lus-terrestris.htm. Accessed January 12, nate for several years afterwards. Hand Both species of weevils are available 2006. removal, hoeing, or cultivation should for purchase from biological control be initiated prior to flowering and seed suppliers but purchase and release is Donaldson, S. and D. Rafferty. 2003. production. Mowing is not an effective not generally recommended because Identification and Management of Punc- method of control since the plant grows weevils collected from other areas turevine (Tribulus terrestris L.). Nevada low to the ground. may not survive at your location. In ◆ 2 of 3 ◆ March 2006 Puncturevine Cooperative Extension Fact Sheet FS-03- 34. http://www.unce.unr.edu/publica- tions/FS03/FS0334.pdf Legner, E. F.