USGS Weeds in the West project: Status of Introduced Plants in Southern Arizona Parks

Factsheet for:

Tribulus terrestris L.

William L. Halvorson, Principal Investigator Patricia Guertin, Research Specialist

U.S. Geological Survey / Southwest Biological Science Center

Sonoran Desert Field Station University of Arizona

125 Biological Sciences East Tucson, Arizona 85721

Prepared by Patty Guertin December 31, 2003

Funded by: U.S. Geological Survey National Park Service

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Table of Contents:

Tribulus terrestris L. .............................................................................................................................3 puncturevine, punctureweed, goatshead, tackweed, Mexican sandbur, bullhead, burnut, ground burnut, caltrop, land caltrop ................................................................................................................3

synonymous names of the species:................................................................................................... 3

species taxonomy ................................................................................................................................. 3 image of plant ...................................................................................................................................5

similar native or non-native species that could confuse identification.................................. 5

biology .................................................................................................................................................... 6 growth and reproductive strategy:...................................................................................................6 seed production: ................................................................................................................................7 seed dispersal:...................................................................................................................................7 seed longevity: ..................................................................................................................................8

ecology.................................................................................................................................................... 8 origin and history of introduction: ...................................................................................................8 ecological distribution / habitat:.......................................................................................................8 climatic requirements and limitations: ...........................................................................................9 germination:......................................................................................................................................9 soil preferences: ..............................................................................................................................10 competitive abilities:.......................................................................................................................11 why it does well as an exotic: .........................................................................................................11

effect on natural processes/description of the threat ............................................................... 11

known general distribution............................................................................................................. 12 United States: .....................................................................................................................................12 Arizona, by county: .............................................................................................................................12 National Park Service, southern Arizona group: ..............................................................................12

Casa Grande Ruins National Monument ......................................................................................13 Chiricahua National Monument....................................................................................................13 Coronado National Memorial.........................................................................................................13 Fort Bowie National Historic Site..................................................................................................13 Montezuma Castle National Monument and Montezuma Well unit ...........................................13 Organ Pipe Cactus National Monument .......................................................................................14 Saguaro National Park...................................................................................................................14 Tonto National Monument.............................................................................................................14 Tumacacori National Historical Park............................................................................................14 Tuzigoot National Monument ........................................................................................................14

Weeds in the West Project..................................................................................................................15

control methods and management strategies ............................................................................. 15 Competition:........................................................................................................................................15 Hand labor: .........................................................................................................................................15 Mowing/Mechanical:...........................................................................................................................15 Grazing:...............................................................................................................................................15 Herbicides ...........................................................................................................................................15 Biological controls:..............................................................................................................................16 Control strategies: ..............................................................................................................................17

contacts or technical specialists .................................................................................................... 17

bibliography........................................................................................................................................ 18

additional sources and websites .................................................................................................... 22 websites with great plant photos: ......................................................................................................23 websites with simple plant descriptions and/or photos: ...................................................................23 some websites with great info: ...........................................................................................................23

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Tribulus terrestris L.

puncturevine, punctureweed, goatshead, tackweed, Mexican sandbur, bullhead, burnut, ground burnut, caltrop, land caltrop

family: Zygophyllaceae synonymous names of the species:

the first name in each species list is the current and synonymous name used by Kartesz (1994).

the name in bold type occurring within each species list indicates the plant name used within these documents, which is also the name provided in the southern Arizona NPS exotics database ‘soaraz~1.xls’ (Holden 1996). Tribulus terrestris L. no synonymous names

species taxonomy Tribulus terrestris L., goatshead, puncture vine: From California Department of Food and Agriculture, EncycloWeedia (2002), Downton (1975), Felger (2000), Hickman (1993), Kearney and Peebles (1960), Parker (1972), Reddi et al. (1981), Shreve and Wiggins (1964), Squires (1979), USDA,NRCS, The PLANTS database (2001), Whitson et al. (1992): (A glossary is provided at the end of this section for the plant terminology used in this section.)

life strategy: a C4, summer annual; ephemeral. Reproduces by seed. In tropical areas, this plant develops woody roots and becomes perennial. 2n=12, 24, 36, 48.

structure: prostrate spreading radially, generally less than 3.3 ft. (1 m) in diameter, herbaceous annual plant; mat forming.

roots: deep taproot (to 8.5 ft. (2.6 m)); slender, branched, often somewhat woody, with a network of fibrous roots.

stems: prostrate stems up to 8 ft. (2.4 m) long. Stems highly branched, green to reddish-brown, and spreading radially from the crown along open ground; can be more or less erect when shaded or competing with other plants. Stems are silky or appressed-hairy, sharply bristly to glabrous.

branching: radially spreading stems (from the crown); the stems highly branched.

stipules: stipules leaf-like, subulate, 2-3 mm long.

leaves: cotyledons oblong, 0.2-0.6 in. (5-15 mm) long, creased down the center, slightly indented at the tips. Leaves opposite; even-pinnate compound, approximately 0.4-2 in. (1-5 cm) long, with 3-7 leaflet pairs per leaf; and having a small extension at the rachis tip. Leaflets elliptic or oblong, 0.1-0.6 in. (3-15) mm long, with more or less oblique bases; lower leaflet pair unequal in size. Foliage often sparse to moderately silky-strigose to glabrous.

inflorescence: peduncled flowers, solitary in axils of leaves.

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calyx/sepals or phyllaries: sepals 5 (occasionally 4), caducous. Sepals narrowly lance-ovate, 0.1-0.14 in. (3-3.5 mm) long.

corolla/petals: peduncle reflexed; shorter than subtending leaves. Flowers are axillary, solitary; corolla/petals bright yellow, 0.2-0.6 in. (5-15 mm) in diameter, 0.2 in. (5 mm) or less long. Petals 5 (occasionally 4), deciduous. 5 glands occur between the stamens at the base of the ovary. Flowers perfect. Flowers are open in the mornings, close in the afternoons.

gynoecium: ovary has 5 carpels. Ovary chambers twice the number of petals; a traverse partition separates seeds in each carpel. Style deciduous. Styles connate into a stout column. Stigmas 5.

androecium: stamens twice the number of petals, usually 10. 5 shorter stamens, anthers well below the level of the stigma, opposite the sepals, each subtended by a small gland; 5 longer stamens, anthers at the same height of the stigma, opposite the petals.

fruit: a schizocarp; woody burrs, gray to yellow-tan, hairy, to approximately 0.4-0.7 in. (1-1.8 cm) in diameter, more or less flattened, lobed; separates into 5 (occasionally 4) wedge-shaped, indehiscent nutlets (cocci), each with 2 stout dorsal spines 0.15-0.27 in. (4-7 mm) long and spreading, and several prickles.

seeds: usually 2-5 per nutlet (coccus), remain enclosed within the burrs (coccus).

taxonomic glossary (Harris and Harris 1997): adnate: fusion of unlike parts appressed: pressed close or flat caducous: falling off early compared to similar structures in other plants canescent: white or gray in color, due to a covering of short, fine white or gray hairs connate: fusion of like parts cotyledons: a primary leaf of the embryo even-pinnate: pinnately compound having a terminal pair of leaflets or a tendril, thus

having an even number of leaflets glabrate: becoming or almost glabrous glabrous: smooth, hairless hirsute: pubescent, with short, stiff hairs oblique: having unequal sides, as a leaf base pedicel: the stalk of a solitary flower in an inflorescence, or of a grass spikelet peduncle: the stalk of a solitary flower or of an inflorescence perfect: having both male and female reproductive organs pinnate: a compound leaf with leaflets arranged on opposite sides of the rachis puberulent: having fine, short hairs rachis: the main axis of a structure (as in a compound leaf or inflorescence) reflexed: bent backwards or downwards reticulate: in the form of a network strigose: having straight, stiff, sharp, appressed hairs subulate: awl-shaped tubercle: a small tuber-like swelling or projection tuberculate: having tubercles

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image of plant

similar native or non-native species that could confuse identification There are several native species in the genus Kallstroemia (family: Zygophyllaceae) that could be confused with Tribulus terrestris: Kallstroemia parviflora and K. californica; especially when the plants haven't begun to flowers and fruits aren't present. They can occur with Tribulus terrestris in disturbed areas, especially when disturbance occurs in a more ‘natural’ setting, or they can occur in those same areas alone. They are easiest to distinguish from each other when the fruits have fully matured, the fruits being very different from each other. Tribulus terrestris more often has the smaller flowers that are brighter yellow (versus yellow-orange), although variability within each species and taxa often makes these generalities deficient for proper identification. Also, there are some general and subtle differences in the leaves (leaflet number, shape, and hairiness), and getting to know each plant well seems to be the best remedy for proper in-the-field identification. Below are descriptions of the taxa; see glossary above for definitions of terminology.

photo by Patty Guertin

copyright by James Reveal: photo obtained at USDDA/NRCA Plants (2001) website: Tribulus terrestris

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Kallstroemia parviflora: spreading stems, branched, to 3.3 ft. (1 m) long, mat forming. Leaves are 0.4-1.2 in. (1-3 cm) long; with 3-5 pairs of leaflets, 0.3-0.4 in. (7-10 mm) long, acute at both ends, hirsute beneath, glabrous above. Stipules 0.2-0.3 in. (6-7 mm) long, linear lanceolate; persistent. Flower pedicels 0.4-0.8 in. (1-2 cm) long; up to 1.6 in. (4 cm) in fruit. Sepals approximately 0.2 in. (5 mm) long, hirsute, persistent. Petals orange-yellow, often fading, 0.2-0.5 in. (6-12 mm) long, 0.1-0.2 in. (2-4 mm) wide; deciduous. Fruit 0.2 in. (5-6 mm) wide; carpels bluntly tuberculate on backs; beak 0.2 in. (4-6 mm) long, strongly conic at base, columnar (Kearney and Peebles 1960, Shreve and Wiggins 1964). Occurs in Navajo to Mohave counties, south to Greenlee, Cochise, Santa Cruz, and Pima counties; 1000-5000 ft. Kallstroemia californica var. californica: spreading stems, branched, to 4-24 in. (1-6 dm) long. Leaves 0.6-2.4 in. (1.5-6 cm) long; with 4-7 pairs of leaflets, broadly elliptic, 0.2-0.4 in. (4-10 mm) long; obliquely obtuse at base, obtuse or rounded at apex; strigose-canescent or tardily glabrate above, most of the hairs appressed. Stipules linear-subulate to ovate, 0.05-0.1 in. (1.5-3 mm) long; usually caducous. Flower pedicels 0.6 in. (1.5 cm) long or less. Sepals narrowly lance-ovate, 0.1-0.2 in. (3-4 mm) long; usually deciduous in fruit. Petals orange-yellow, 0.2 in. (4-6 mm) long; deciduous. Fruit 0.1-0.2 in. (3-4.5 mm) in diameter, 0.1 in. (3-3.5 mm) high, puberulent; carpels with sharp tubercles, often to 1.5 mm long, on backs; beak 3 mm long, conic at base, glabrous in fruit (Kearney and Peebles 1960, Shreve and Wiggins 1964). Occurs in south and southwestern Arizona, Graham to Yuma counties; 7000 ft. or lower. Kallstroemia californica var. brachystylis: spreading stems, branched, to 4-24 in. (1-6 dm) long. Leaves 0.6-2.4 in. (1.5-6 cm) long; with 3-5 pairs of leaflets, broadly elliptic, 0.2-0.6 in. (6-15 mm) long; obliquely obtuse at base, obtuse or rounded at apex; strigose-canescent or tardily glabrate above. Stipules linear-subulate to ovate, 0.05-0.1 in. (1.5-3 mm) long; usually caducous. Flower pedicels 0.6 in. (1.5 cm) long or less. Sepals narrowly lance-ovate, 0.1-0.2 in. (3-4 mm) long; usually deciduous in fruit. Petals orange-yellow, 0.2 in. (4-6 mm) long; deciduous. Fruit 0.1-0.2 in. (3-4.5 mm) in diameter, 0.1 in. (3-3.5 mm) high; carpels with low, rounded tubercles, on backs, these sometimes sharper; sides of carpels strongly reticulate (Kearney and Peebles 1960, Shreve and Wiggins 1964). Occurs in central and northern Arizona, Apache, Coconino, and Yavapai counties, south to central Arizona; 7000 ft or lower.

biology growth and reproductive strategy:

Tribulus terrestris is a C4, summer annual, reproducing by seed; it is prostrate and mat-forming. Tribulus terrestris plant material from California was found to be diploid; 2n=24 (Heiser and Whitaker 1948).

Generally, Tribulus terrestris has a considerable seed dormancy lasting over fall and winter months (Washington State Noxious Weed Control Board 2002) with some seeds staying dormant for longer periods of time. Its seedlings emerge in the early spring through summer, often in flushes following increased soil moisture (California Department of Food and Agriculture, EncycloWeedia 2002). It germinates after the start of the monsoon rains, on any type of barren soil, in southern Arizona (Parker 1972). In Washington and Australia, it germinates in the late spring to early

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summer, when necessary soil moisture conditions are met (Squires 1979, Washington State Noxious Weed Control Board 2002).

It is a prostrate mat-forming plant with trailing stems, although can be more ascending when light competition exists on a site (Holm et al. 1991, Yolo County Resource Conservation District 2002). Seedlings develop a deep root system in a few weeks; flowers may be produced within 3 weeks, fruits/burrs within 6 weeks (California Department of Food and Agriculture, EncycloWeedia 2002, Washington State Noxious Weed Control Board 2002). Tribulus terrestris roots can develop nitrogen-fixing nodules (Athar and Mahmood 1985, California Department of Food and Agriculture, EncycloWeedia 2002). Athar and Mahmood (1985) observed that plants having root nodules had more lush green healthy growth and greater dry weight versus stunted growth in plants without nodules.

Boydston (1990) reports that flowering occurred within 3-4 weeks of emergence when temperatures were consistently above 68°F (20°C), regardless of planting date. Tribulus terrestris flowers March through October in Arizona, although primarily from July to August (Parker 1972). Once the plant begins to flower, it is continuous throughout the plant's life (Reddi et al. 1981). Tribulus terrestris flowers are cross-pollinated by insects (foragers include: Coleoptera, Diptera, Hymenoptera, Lepidoptera, Thysanoptera) (California Department of Food and Agriculture, EncycloWeedia 2002, Washington State Noxious Weed Control Board 2002) along with being self-pollinated, which occurs at the end of each flower's receptive period (within one day) (Reddi et al. 1981). Self-pollination is accomplished when the petals begin to close and push the stamen inward toward the stigma, the longer anthers making direct contact; the potential of this system is 100% seed set (Reddi et al. 1981). Fruits mature in approximately 2 weeks, and subsequently split apart into segments soon afterward (Holm et al. 1991). Plants continue to reproduce and produce fruit until the cool season begins. Boydston (1990) reports during trials in Washington, fruit/burr production stopped in October when average temperatures were under 68°F (20°C)

Squires (1979) reports that the plant can be killed by frost or drought. At senescence, the fruits/burrs often remain on the plant or the soil surface (California Department of Food and Agriculture, EncycloWeedia 2002). In India, it was observed that seeds may still germinate in the fall, yet the seedlings fail to establish due to declining seasonal temperatures (Pathak 1970). In tropical regions under suitable conditions, Tribulus terrestris develops woody roots and becomes perennial (California Department of Food and Agriculture, EncycloWeedia 2002, Holm et al. 1991).

seed production:

Tribulus terrestris plants typically bear numerous fruits/schizocarps/burrs (averaging 200-5000 per plant) (California Department of Food and Agriculture, EncycloWeedia 2002).

Boydston (1990) reports that seeds planted in May, June, July, and August subsequently produced 5600, 5200, 3600, and 200 burrs/plant, respectively. Although, fruit/burr production seemingly responds to temperatures during a season's growth, enabling greater production for a longer period of time in warmer years (Boydston 1990). Each fruit/burr usually contains 5 nutlets (cocci), each nutlet (coccus) can contain 2-5 seeds (Boydston 1990).

seed dispersal:

Each fruit section (coccus) has 2 sharp divergent spines and several other spines and warty protuberances enabling the Tribulus terrestris fruits to easily attach to

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animals and humans and to stick onto vehicle tires (cars, farm, airplane), subsequently facilitating long distance dispersion and spread (Ernst and Tolsma 1988, Ridley 1930, Squires 1979, Whitson 1992). Holm et al. (1991) points out that due to the architecture of the schizocarp/fruit, the large and small spines are arranged at different angles with at least one of the spines always pointing upward no matter how the fruits/burrs fall from the plant, and can easily imbed into feet, hooves, or tires. After getting caught or imbedded into the hooves, feet, and wool of livestock and other animals, the fruits/burrs are subsequently broken off as the animals try to rid themselves of the irritation (Ridley 1930). Furthermore, they can stick to the shoes and clothing of people, and the fur and feathers of animals (California Department of Food and Agriculture, EncycloWeedia 2002).

Tribulus terrestris fruits/burrs are also a contaminate of seed, feed, and wool of livestock (Johnson 1932 in Gould and DeLoach 2002).

Foy et al. (1983) report that Tribulus terrestris "presumably" was unintentionally imported into the United States on the tires of military planes returning from the Sahara Desert region; and has been further spread on this continent on the tires of aircraft and cars.

seed longevity:

Buried Tribulus terrestris seed can remain viable for several years (California Department of Food and Agriculture, EncycloWeedia 2002), staying dormant in the soil for 4-5 years (Whitson 1992).

ecology origin and history of introduction:

Tribulus terrestris is native to southern Europe (GRIN 2000, Parker 1972), Africa, temperate and tropical Asia (Afghanistan, Armenia, Azerbaijan, China, Cyprus Sinai, Georgia, Iran, Iraq, Israel, Japan, Jordan, Kazakhstan, Kyrgyzstan, Lebanon, Mongolia, Russian Federation (Ciscaucasia, southeast Western Siberia), Saudi Arabia, Syria, Tajikistan, Turkey, Turkmenistan, Uzbekistan, India, Pakistan), and north Australia (GRIN 2000); it was introduced here from the Mediterranean (California Department of Food and Agriculture, EncycloWeedia 2002). Squires (1979) comments that Tribulus terrestris probably originated in the Saharan region, and spread into the Mediterranean region.

Tribulus terrestris was accidentally imported from the Mediterranean into the United States on livestock (Andres and Goeden 1995 in Gould and DeLoach 2002, Washington State Noxious Weed Control Board 2002). It was first reported in California in 1903 (Davidon 1903 in Squires 1979, PRIDE 2002).

ecological distribution / habitat:

Tribulus terrestris occurs widely throughout the world from latitudes 35°S to 47°N (Holm et al. 1991). As a weed, it occurs in the subtropics and warm temperate zone (Holm et al. 1991). It frequently concentrates at low elevations in coastal areas (Holm et al. 1991).

In its native area: Within its native range in Eurasia, from the central Russian steppe through Mongolia, Manchuria, Germany, Poland, and the countries bordering the Mediterranean (Squires 1979) it is present at elevations ranging from near sea level to above 3,280 ft. (1000 m) (Squires 1968 in Squires 1979).

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On the North American continent: Tribulus terrestris is found throughout California to Wyoming, to eastern United States, and south to central Mexico (California Department of Food and Agriculture, EncycloWeedia 2002). Tribulus terrestris habitat is disturbed places, along city streets and roadsides, railways, cultivated fields and orchards, barnyards and pastures, fallow fields, lawns and yards, playgrounds, waste places, open sandy sites, and walk ways (California Department of Food and Agriculture, EncycloWeedia 2002, Hickman 1993, Holm et al. 1991, Parker 1972).

In Arizona, Tribulus terrestris is found to 7000 ft. (2134 m) (Parker 1972).

climatic requirements and limitations:

Tribulus terrestris is adapted to warm, temperate regions (Washington State Noxious Weed Control Board 2001) and is prevalent in areas having hot summers, on dry soils (California Department of Food and Agriculture, EncycloWeedia 2002). Tribulus terrestris requires relatively high temperatures for growth (Washington State Noxious Weed Control Board 2001), and is intolerant of freezing temperatures (California Department of Food and Agriculture, EncycloWeedia 2002, Squires 1979).

In Australia in places where Tribulus terrestris is a major weed, the daily maximum temperatures in summer are above 84°F (29°C) (Squires 1979).

In a database covering the northwestern United States, Tribulus terrestris occurs in areas having a mean minimum July temperature of 67°F (19.4°C) and a mean maximum July temperature of 73°F (22.8°C), and a mean minimum January temperature of 17°F (-8.3°C), and a mean maximum January temperature of 24°F (-4.4°C) (Rice 2002).

Tribulus terrestris occurs in areas with a mean annual minimum precipitation of 11 in. (28 cm) and a mean annual maximum precipitation of 15 in. (38 cm) (Rice 2002).

Tribulus terrestris seedling establishment was observed to be poor on sites that were shaded (Pathak 1970).

germination:

Most newly matured Tribulus terrestris seeds are dormant and require an after-ripening period of approximately 6-12 months. Ernst and Tolsma (1988) report that dormancy of seeds was very high in both fresh seeds and 3-6 year old seeds. Squires (1968 in Squires 1979) reports that freshly harvested seeds have a germination rate of 10%, and dry-stored 6-month-old seeds have a germination rate of 84%. Imbibition of water differed in dormant versus non-dormant seeds: measurements taken at one hour and periodically through one day of imbibition showed dormant seeds had approximately half of the water content of non-dormant seeds (Ernst and Tolsma 1988). The largest seed within a nutlet (coccus) is usually the first to germinate; the remaining seeds may germinate or remain dormant depending on moisture availability (California Department of Food and Agriculture, EncycloWeedia 2002); this large seed is usually positioned near the basal end of the burr (coccus) (University of California 1998).

Pathak (1971 in Squires 1979) reports that Tribulus terrestris germination is inhibited by low temperatures, low light intensities, and wet soil. The optimum temperature range for germination to occur is 81-95°F (27-35°C). In Australia, germination occurs when the maximum air temperature is approximately 75-81°F (24-27°C) (Squires 1979). During trials, Tribulus terrestris emergence was initiated when average soil temperatures reached 59°F (15°C) for at least 2 weeks and approached 68° F (20°C) (Boydston 1990). After initial emergence occurred,

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emergence was multipeaked with no relationship existing with temperature for the remainder of the summer (Boydston 1990). In subsequent years, emergence occurred and peaked at similar times regardless of the age of the seed, indicating environmental stimuli influencing emergence (Boydston 1990).

Tribulus terrestris seedlings emerge during early spring through summer, often in flushes following increased soil moisture (California Department of Food and Agriculture, EncycloWeedia 2002, Mirsa 1962 in Holm et al. 1991). During field observations in Botswana, Tribulus terrestris was observed to germinate and emerge following a rainshower having more than 0.04 in. (10 mm) of precipitation (Ernst and Tolsma 1988). Maximum germination occurred after a series of heavy rains, facilitating a 35% germination rate, with continued germination of seeds lasting for another 4 months (Ernst and Tolsma 1988).

On sandy soils, seedlings emerge from depths to approximately 5 cm (less on heavy soils) (California Department of Food and Agriculture, EncycloWeedia 2002). Squires (1968 in Squires 1979) reports that seeds buried more than 4 in. (10 cm) deep in sandy soils, can successfully emerge.

Germination was irregular in Tribulus terrestris seeds, whether seeds remained in the fruit (cocci) or were isolated (Ernst and Tolsma 1988). In greenhouse trials, the highest germination rate was achieved by isolated seeds with a maximum of 66.9%, and a mean of 37.3±25.1% (ranging from 68/59°F (20/15°C) up to 95/86°F (35/30°C), in 5°C increments, alternating day/night temperatures). Seeds that remained in the fruits rarely germinated synchronously (Ernst and Tolsma 1988). Ernst and Tolsma (1988) add that because of this pattern, direct competition for water and nutrients is avoided.

soil preferences:

Tribulus terrestris grows best on dry, sandy soils, but can tolerate most soil types (California Department of Food and Agriculture, EncycloWeedia 2002, Washington State Noxious Weed Control Board 2001). In Australia, Tribulus terrestris is found on sandy and silty, and on saline soils (Squires 1979). In India, Tribulus terrestris is found primarily on loose and compact sandy loam soils, and reportedly grows on sand dunes in the desert regions (Pathak 1970). It also thrives on loose, blown soil by field margins (Holm et al. 1991). Plants are typically more robust on sites without compacted soils (Pathak 1970), yet can grow on compacted soils, such as those found alongside unsurfaced roads and in playgrounds (Holm et al. 1991). It also can grow in heavier soils, especially when fertile and moist (Holm et al. 1991).

During tests in India, soil moisture was observed to average 3.54-6.74%, and occasionally lowered to 1.8% during Tribulus terrestris's life (Pathak 1970). Water holding capacity of soils of acceptable habitat for Tribulus terrestris range between 35.36-44.9%, with compact soils having lower capacities (Pathak 1970). Additionally, the plant was observed to grow on soils of low nitrogen (Pathak 1970).

Measurements of Tribulus terrestris taken during trials in India uncovered factors affecting the plant's success; that is, dry weight and the plant's seed output was influenced by the amount of organic matter in the soils (ranging between 1.07-3.94% on tested sites). Exchangeable soil calcium influenced dry weight of the shoots and the plant's seed output. And, soil moisture of the soil with the presence of organic matter and exchangeable calcium influenced the dry weight of the shoot and the plant's seed output (Pathak 1970).

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As stated previously, waterlogged sites may cause poor seedling establishment, whereas it was observed that plants were abundant on arable and well-drained sites (Pathak 1970).

competitive abilities:

Due to its ability to extract soil moisture from great depth in the soil, Tribulus terrestris competes well in crops (Holm et al. 1991).

There is also research demonstrating that seedling growth of Pennisetum typhoides is inhibited by root extracts of Tribulus terrestris; root extracts were most harmful when followed by leaf and stem extracts (Sen et al. 1969 in Holm et al. 1991).

Tribulus terrestris is sensitive to competition; typically, where perennial plants are maintained Tribulus terrestris does not become problematic (Squires 1969). In India, it was noted that Tribulus terrestris does not grow in continuous patches, and chooses a sunny location on a site (Pathak 1970). When it is observed in continuous patches on a site, the competition is low on the site (Pathak 1970).

why it does well as an exotic:

Tribulus terrestris is capable of massive population increases over short periods of time, when conditions are favorable (Squires 1979, Washington State Noxious Weed Control Board 2002).

Boydston (1990) notes that erratic and continuous germination of Tribulus terrestris, its seed dormancy enabling seed to germinate over several years from one reproductive effort, and its ability to flower rapidly after emergence makes control difficult. As with other weedy species, it insures not all seeds germinate during favorable conditions, in the event a mass failure occurs. Germination of Tribulus terrestris seed is quick under suitable moisture and temperature conditions (Squires 1979). And, Tribulus terrestris fruits only 10 days old potentially have viable seeds (Johnson 1932 in Squires 1979). Germination after sufficient rain may only yield about 35% germination of seeds; Ernst and Tolsma (1988) suggest that this heterogeneity of seed germination may reduce intraspecific competition for light and nutrients on a site.

As stated previously, the seeds of Tribulus terrestris are viable in soil for up to 4-5 years (making eradication difficult) (Yolo County Resource Conservation District 2002).

Tribulus terrestris plants have deep, and somewhat woody, taproots; the plants are able to obtain moisture and to grow under conditions too rigorous for most plants (Holm et al. 1991). Its large root volume has a tremendous ability to remove water from the soil at very high moisture tension levels (Davis et al. 1965 in Holm et al. 1991). Also, it was found during trials in Texas that its water requirements are much lower than other plants (sorghum, alfalfa), needing 212 lbs. (96 kg) of water to produce 2.2 lbs. (1 kg) of dry biomass (Davis and Wiese 1964 in Holm et al. 1991).

Tribulus terrestris plants potentially produce many thousands of seeds.

Also, its long-distance method of dispersion enable the plant to move almost anywhere.

effect on natural processes/description of the threat no information was found on Tribulus terrestris' impacts to natural areas. A few examples of how it impacts life in general:

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Tribulus terrestris is listed as a regulated and restricted noxious weed in Arizona, causing impacts to crops and animals. Tribulus terrestris fruits (with their sharp, stout spines) cause considerable nuisance in public areas. They also can seriously injure grazing animals (Squires 1979).

known general distribution United States:

Arizona, Arkansas, California, Colorado, Florida, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, Wisconsin, Wyoming (USDA,NRCS, The PLANTS database 2001: Map available at Website: http://plants.usda.gov/plants/ ; then enter the common or scientific name).

Arizona, by county:

found throughout the state, 7000 ft. or lower (Kearney and Peebles 1960, McDougall 1973, Parker 1972).

National Park Service, southern Arizona group:

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Casa Grande Ruins National Monument

source listing species’ presence in park: no sources found

Chiricahua National Monument source listing species’ presence in park: Bennett, P.S., R.R. Johnson, and M.R. Kunzmann. 1996. An annotated list of vascular

plants of the Chiricahua Mountains: Including Pedregosa Mountains, Swisshelm Mountains, Chiricahua National Monument, and Fort Bowie National Historic Site. Special Report No. 12. United States Geological Survey, Biological Resources Division, Cooperative Park Studies Unit, The University of Arizona, Tucson, Arizona. 228 pp.

National Park Service. 1993. Checklist of vascular plants of Chiricahua National

Monument, Cochise County, Arizona. U.S. Department of the Interior, National Park Service, Chiricahua National Monument, Dos Cabezas Route, Box 6500, Willcox, Arizona 85643. 48 pp.

Coronado National Memorial

source listing species’ presence in park: Parfitt, B.D. and C.M. Christy. 1992. Coronado National Memorial plant checklist – a

synonymized list of the vascular plants. Department of Botany, Arizona State University, Tempe Arizona 85287-1601. 24 pp.

Fort Bowie National Historic Site

source listing species’ presence in park: Bennett, P.S., R.R. Johnson, and M.R. Kunzmann. 1996. An annotated list of vascular

plants of the Chiricahua Mountains: Including Pedregosa Mountains, Swisshelm Mountains, Chiricahua National Monument, and Fort Bowie National Historic Site. Special Report No. 12. United States Geological Survey, Biological Resources Division, Cooperative Park Studies Unit, The University of Arizona, Tucson, Arizona. 228 pp.

Warren, P., M.S. Hoy, and W.E. Hoy. 1992. Vegetation and flora of Fort Bowie National

Historic Site, Arizona. Technical Report NPS/WRUA/NRTR-92/43. United States Department of the Interior, National Park Service, Western Region, Cooperative National Park Resources Studies Unit, The University of Arizona, Tucson, Arizona 85721. 78 pp.

Montezuma Castle National Monument and Montezuma Well unit

source listing species’ presence in park: Brian, N.J. and P.G. Rowlands. 1994. An annotated vascular plant species list for

Montezuma Castle and Montezuma Well National Monuments, Arizona. Technical Report, Colorado Plateau Research Station, National Biological Survey, P.O. Box 5614, Flagstaff, AZ 86011-5614. 77 pp.

14

Rowlands, P.G. 1999. Vegetation survey of Montezuma Castle National Monument. Division of Resources Management, Organ Pipe Cactus National Monument, Route 1, Box 100, Ajo, Arizona 85321. 107 pp.

Organ Pipe Cactus National Monument

source listing species’ presence in park: Felger, R.S. 1990. Non-native plants of Organ Pipe Cactus National Monument,

Arizona. Technical Report No. 31. U.S. Geological Survey, Cooperative Park Studies Unit, The University of Arizona and National Park Service, Organ Pipe Cactus National Monument. 93 pp.

Felger, R.S. and S. Rutman. 2000; draft. The flora of Organ Pipe Cactus National

Monument. 18 pp.

Saguaro National Park source listing species’ presence in park: Bowers, J.A. 1984. Woodland and forest flora and vegetation of Saguaro National

Monument. Submitted to Saguaro National Park. 148 pp. Bowers, J.A. and S.P. McLaughlin. 1987. Flora and vegetation of The Rincon

Mountains, Pima County, Arizona. Desert Plants 8(2):51-94. Rondeau, R., T.R. Van Devender, C.D. Bertelsen, P. Jenkins, R.K. Wilson, M.A.

Dimmitt. 1996. Annotated flora and vegetation of the Tucson Mountains, Pima County, Arizona. Desert Plants 12(2):3-46.

Van Devender, R. 1992. Floristic survey of a proposed protected natural area within

Saguaro National Monument, Tucson Mountains Unit: Final Report. National Park Service, Funding #1443 PX8670-92-042.

Tonto National Monument

source listing species’ presence in park: no sources found

Tumacacori National Historical Park source listing species’ presence in park: Bennett, P. year unknown. Reference list. (A list of plants of Tumacacori National

Historic Park; obtained in 1999). Unpublished; created while an employee (plant ecologist) of USGS/BRD/Sonoran Desert Field Station, The University of Arizona, Tucson, Arizona. 11 pp.

Mouat, D.A., S.J. Walker, and B.D. Treadwell. 1977. The Tumacacori Mission National

Monument floral inventory and vegetation map project. Office of Arid Land Studies, Applied Remote Sensing Program, The University of Arizona, Tucson, Arizona, 85719. 11 pp.

Tuzigoot National Monument

source listing species’ presence in park: no sources found

15

Weeds in the West Project While completing distribution mapping between Spring 1999 through Spring 2001 for the USGS Weeds in the West project in the southern Arizona National Park Service management units, Tribulus terrestris (goatshead, puncture vine) was found in the following parks (Guertin 2001):

Casa Grande Ruins National Monument Chiricahua National Monument Coronado National Memorial Fort Bowie National Historic Site Saguaro National Park Tumacacori National Historical Park

control methods and management strategies Competition: As stated previously, Tribulus terrestris does not become problematic in perennial

plants; it is sensitive to competition (Squires 1969 in Squires 1979). Therefore, planting competitive vegetation can help control infestations (California Department of Food and Agriculture, EncycloWeedia 2002).

Hand labor: Removal of plants with fruits/burrs and repeated cultivation to prevent seed

production and fruit/burr formation can help control infestations (California Department of Food and Agriculture, EncycloWeedia 2002). Tribulus terrestris plants should be howed off below the crown at the root, and if plants have produced fruits before a cultivation effort is made, subsequent to the effort the plants and fruits should be collected and burned (Muenscher 1980, Washington State Noxious Weed Control Board 2002).

Repeated cultivation just after plant emergence is an effective control (Washington State Noxious Weed Control Board 2002).

Mowing/Mechanical: Frequent light cultivation in areas with Tribulus terrestris seedlings may be effective

(Squires 1979). On more mature plants, shallow cultivation to sever the taproot just below the soil surface is suggested (Holm et al. 1991).

Grazing: Holm et al. (1991) notes that there may be several different toxic agents in Tribulus

terrestris. The species has been reported to have toxic levels of nitrate in its tissues (Ragonese 1955 in Holm et al. 1991). Also, Tribulus terrestris foliage is toxic to livestock when consumed in quantity, especially for sheep (California Department of Food and Agriculture, EncycloWeedia 2002); this is caused by an unknown toxin which causes liver damage, and photosensitivation along with other symptoms which can likely cause death especially in young animals (Holm et al. 1991).

The spiked fruits/burrs can cause injury to animals, causing reduced grazing in pastures (Holm et al. 1991).

Herbicides

16

Picloram used as a pre-emergent can give adequate control. Young Tribulus terrestris plants may be sprayed with amitrole, chlorsulfuron, or 2,4-D (Washington State Noxious Weed Control Board 2002).

Rice (1992) lists 2,4-D, MCPA, MSMA, atrazine, bromoxynil, chlorsulfuron, dicamba, glyphosate, norflurazon, oryzalin, oxyfluorfen, simazine, tebuthiuron, trifluralin for puncture vine.

Parker (1997) lists 2,4-D, MSMA, amitrole, bromacil & diuron, chlorsulfuron, norflurazon, paraquat for puncture vine.

Colorado Natural Areas Program (2000) lists dicamba, picloram, and glyphosate as providing excellent control, and 2,4-D as providing good control of Tribulus terrestris.

Cautions and considerations: Herbicides, as with all management / control methods, take careful planning and attention to detail for a particular site (climate/weather, soils, topography, vegetation or lack thereof, sensitive areas, land use, target plant and infestation characteristics) and the goals to be accomplished on the site.

A major consideration when using herbicides is the sensitivity and hazard to other non-target species and organisms in the area (Callihan et al. 1995, Horowitz 1996). Many of the herbicides are 'non-selective' and useful for agricultural operations, but not necessarily intended for natural environments. Even the 'selective' chemicals can harm other plants when not applied properly or when used in places where other native plants are vulnerable to their mode of action (Horowitz 1996). Improper application and /or application rates can harm many other species, along with affecting water quality; the eventual accumulation of these compounds in underground and aboveground water bodies (Callihan et al. 1995, Horowitz 1996). Also, to be considered is the potential resistance a biotype may develop to some of these compounds over time (Horowitz 1996).

The information provided here is meant to give a glimpse of what has been learned, and found effective. It might not necessarily be the best approach in the Sonoran Desert; generally the environments reported on are not desert lands as little research has been done in natural environments of the Sonoran Desert to date. Nor do the same application or herbicide use laws apply across state borders in all cases. Contacts / specialists' names or offices are provided in the following section for follow up and gathering of more information pertinent to a specific environment or site.

Table 1 offers information on the herbicides in this section. Biological controls: Tribulus terrestris is controlled by introduced weevils (Hickman 1993) native to

India, France, and Italy (Washington State Noxious Weed Control Board 2002) and brought into California. They are the stem weevil (Microlarinus lypriformis) and the seed weevil (Microlarinus lareynii), and were introduced in 1961 as a biocontrol agent (Gould and DeLoach 2002). Both of these weevils have established in California and Arizona; substantial success has been obtained in nonirrigated areas, with a partial success overall (Gould and DeLoach 2002). In areas of Texas and New Mexico, success is being defined as 'complete' with Tribulus terrestris difficult to find, although years of plentiful precipitation or irrigation, along with parasites and predators of the weevils, have limited complete eradication (Gould and DeLoach 2002).

17

In Hawaii, these same two weevils were released in 1962 and 1964 with Tribulus terrestris being completely eradicated in many areas within 4 years (Davis and Krauss 1966 in Markin et al. 1992).

Control strategies: Control strategies of Tribulus terrestris include the removal of fruiting plants, with

repeated cultivation to prevent seed production (California Department of Food and Agriculture, EncycloWeedia 2002, Holm et al. 1991).

For best results, control methods would have to eliminate early season to mid-season seedling establishment (April to end of July in Washington) given that these plants are more capable of greater seed production (Boydston 1990). As stated previously, the irregular and continuous germination of Tribulus terrestris, its seed dormancy, and its ability to flower rapidly after emergence will make control difficult (Boydston 1990).

contacts or technical specialists Dr. Francis E. Northam (Ed Northam)

Noxious Weed Coordinator, Plant Services Division Arizona Department of Agriculture 1688 West Adams Street Phoenix, Arizona 85007 Phone: (602) 542-3309: FAX: (602) 542-1004 e-mail: ed.northam@agric.state.az.us Ed works state-wide primarily with noxious agricultural weeds, yet has also done some

work to get non-native invasive plants listed that impact Arizona’s natural environments

He indicated he would provide, as requested, information regarding: weed biology control/management of weeds

Dr. John H. Brock

Professor of Applied Biological Science Coordinator of Sustainable Technologies, Agribusiness and Resources (STAR) Research

Center Arizona State University East 7001 E. Williams Field Rd. Mesa, Arizona 85212 Phone: (480) 727-1240; FAX (480) 727-1961 e-mail: john.brock@asu.edu Dr. Brock has done:

invasive plant work (including control treatments) in essentially all the major vegetation types in Arizona, except the highest elevation types like mixed conifer.

April Fletcher, Arizona Interagency Weed Action Group

U.S. Fish and Wildlife Service P. O. Box 1306 500 Gold Ave. Albuquerque, New Mexico 87103 e-mail: April_Fletcher@fws.gov April works region-wide with on-the-ground folks. Arizona Interagency Weed Action

Group (IWAG) is an ad-hoc group; working on specific projects identified as species of

18

concern by the group. IWAG consists of invasive weed folks from state and Federal resource management agencies.

April is: acquainted with control methods for numerous species she knows many professionals who are doing control work, so, when she can’t

supply an answer, she can usually provide contacts who can. Jim Horsley, Southwest Vegetation Management Association

Arizona Department of Transportation 2104 S. 22nd Avenue Phoenix, Arizona 85009 Phone: (602) 712-6135 email: jhorsley@dot.state.az.us Jim indicated at ADOT they manage and control a number of native and non-native

invasive species. Their experience includes Centaurea solstitialis (Yellow) and Centaurea melitensis (Malta) star thistle,

Onopordum acanthium (Scotch), Carduus nutans (Musk), and Cirsium vulgare (Bull) thistle, Acroptilon repens (Russian), Centaurea biebersteinii / Centaurea maculosa (spotted), and Centaurea diffusa (diffuse) knapweed, Alhagi maurorum (Camelthorn), Halogeton glomeratus (Halogeton), Salsola sp. (Russian thistle, tumbleweed), Linaria damatica (Dalmation toadflax), Cardaria draba (Hoary cress), Tribulus terrestris (Puncture vine), Cenchrus sp. (sandbur), Convolvulus arvensis (Field bindweed), Sorghum halepense (Johnsongrass), Pennisetum ciliare (Buffelgrass), Pennisetum setaceum (Fountain grass), several mustards, Verbascum sp. (mullein), Heterotheca subaxillaris (Camphorweed) and several others.

Jim has personal experience statewide and, has access to other experts from several states in the southwest.

bibliography Andres, L.A., and R.D. Goeden. 1995. Puncturevine. In: Nechols, J.R. et al. (eds).

Biological control in the western United States: Accomplishments and benefits of regional research project W-84, 1964-1989. University of California Publication 3361.

Athar, M., and A. Mahmood. 1985. Observations on nitrogen fixation by Tribulus terrestris

Linn. under natural habitat. Geobios 12(1):44-46. Boydston, R.A. 1990. Time of emergence and seed production of Longspine sandbur

(Cenchrus longispinus) and Puncturevine (Tribulus terrestris). Weed Science 38(1):16-21.

California Department of Food and Agriculture, EncycloWeedia. 2002. Tribulus. Ed by:

Healy, E.A., S. Enloe, J.M. DiTomaso, B. Roberson, N. Dechoretz, S. Schoenig, P. Akers, L. Butler, and J. Garvin. Non-Cropland Weed group, UC Extension Service, Weed Science Program, Department of Vegetable Crops, The University of California. Davis, CA. 95616. website: http://pi.cdfa.ca.gov/weedinfo/TRIBULUS2.htm

19

Callihan, B., L. Smith, J. McCaffrey, and E. Michalson. 1995. Yellow starthistle management for small acreages. University of Idaho, Cooperative Extension System, Agricultural Experiment Station; CIS 1025. 8 pp.

Colorado Natural Areas Program. 2000. Creating an integrated weed management plan: A

handbook for owners and manager of lands with natural values. Colorado Natural Areas Program, Colorado State Parks, Colorado Department of Natural Resources, Division of Plant Industry, Colorado Department of Agriculture. Denver, Colorado. 349 pp. Website: http://parks.state.co.us/cnap/IWM_handbook/IWM_index.htm Click on index for appropriate plant family to find species

Davidson, A. 1903. New plant records for the Los Angeles County, Part II. Southern

California Academy of Science Bulletin 2, 43. Davis, C.J., and N.L. Krauss. 1966. Recent introductions for biological control in Hawaii --

XI. Proceedings of the Hawaiian Entomological Society 19(2):201-204. Davis, R., and A. Wiese. 1964. Weed root growth patterns in the field. p. 367-368. In:

Andrews, H. (ed.). Proceedings of the 17th Southern Weed Conference. Southern Weed Conference, University of Tennessee at Knoxville. 444 pp.

Davis, R., A Wiese, and J. Pafford. 1965. Root moisture extraction profiles of various weeds.

Weeds 13(2):98-100. Downton, W.J. 1975. The occurrence of C4 photosynthesis among plants. Photosynthetica

9(1):96-105. Ernst, W.H., and D.J. Tolsma. 1988. Dormancy and germination of semi-arid annual plan

species, Tragus berteronianus and Tribulus terrestris. Flora 181(3/4):243-251. ExToxNet. 2002. USDA/Extension Service/National Agricultural Pesticide Impact

Assessment Program, A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. Website: http://ace.orst.edu/info/extoxnet/ghindex.html

Felger, R.S. 2000. Flora of the Gran Desierto and Rio Colorado of northwestern Mexico.

The University of Arizona Press. Tucson, Arizona. 673 pp. Foy, C.L., D.R. Forney, and W.E. Cooley. 1983. History of weed introductions. In: Wilson,

C.L., and C.L. Graham (eds.). Exotic plant pests and North American agriculture. Academic Press, New York, New York. 522 pp.

Gould, J.R., and C.J. DeLoach. 2002. Biological control of invasive exotic plant species;

protocol, history, and safeguards. In: Tellman, B. (ed.). Invasive exotic species in the Sonoran Desert region. The University of Arizona Press and The Arizona-Sonora Desert Museum, Tucson, Arizona. 424 pp.

GRIN. 2000. Grin Taxonomy. United States Department of Agriculture, Agricultural

Research Service, The Germplasm Resources Information Network (GRIN).

20

Website: http://www.ars-grin.gov/npgs/tax/index.html then click on 'simple queries of species data' and search for plant species.

Guertin, P. 2001. Observations made during the duration of weed distribution mapping for

the USGS Weeds in the West project occurring in the southern Arizona National Park Service management areas. May 1999-June 2001. USGS/BRD, Sonoran Desert Field Station, The University of Arizona, 125 Biological Sciences East, Tucson, Arizona, 85721.

Harris, J.G., and M.W. Harris. 1997. Plant identification terminology: an illustrated

glossary. Spring Lake Publishing, Spring Lake, Utah. 197 pp. Heiser, Jr., C.B., and T.W. Whitaker. 1948. Chromosome number, polyploidy, and growth

habit in California weeds. American Journal of Botany 35(3):179-186. Hickman, J.C., ed. 1993. The Jepson manual: higher plants of California. University of

California Press. Berkeley and Los Angeles, CA. 1400 pp. Holden, M. 1996; unpublished. Exotic plant species list, compiled for southern Arizona

parks from park floras and exotic plants lists. National Park Service; Saguaro National Park; Tucson Mountain District; 'soazex~1.xls' database, in MS Excel.

Holm, L.G., D.L. Plunknett, J.V. Pancho, and J.P. Herberger. 1991. The world's worst

weeds. Distribution and biology. Krieger Publishing Company, Malabar, Florida. 609 pp.

Horowitz, M. 1996. Bermudagrass (Cynodon dactylon): A history of the weed and its control

in Israel. Phytoparasitica 24(4):305-320. Johnson, E. 1932. The puncturevine in California. Agricultural Experiment Station

Bulletin 528. University of California, College of Agriculture. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States,

Canada, and Greenland: Volume I - Checklist. The biota of North America Program of the North Carolina Botanical Garden. Timber Press, Portland, Oregon. 622 pp.

Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States,

Canada, and Greenland: Volume II - Thesaurus. The biota of North America Program of the North Carolina Botanical Garden. Timber Press, Portland, Oregon. 816 pp.

Kearney, T.H. and R.H. Peebles. 1960. Arizona flora. University of California Press,

Berkeley and Los Angeles, California. 1085 pp. Markin, G.P., P. Lai, and G.Y. Funasaki. 1992. Status of biological control of weeds in

Hawai'i and implications for managing native ecosystems. In: Stone, C.P, C.W. Smith, and J.T. Tunison (eds.). Alien plant invasions in native ecosystems of Hawaii: management and research. University of Hawaii Cooperative National Park Resources Studies Unit, University of Hawaii, Honolulu Hawaii. 887 pp.

McDougall, W.B. 1973. Seed plants of northern Arizona. The Museum of Northern Arizona.

Flagstaff. 594 pp.

21

Mirsa, D. 1962. Tribulus terrestris weed in arid zone farming. Indian Journal of Agronomy

7(2):136-141. Muenscher, W.C. 1980. Weeds. Second Edition. Comstock Publishing Associates, Cornell

University Press, 124 Roberts Place, Ithaca, New York, 14850. 587 pp. Oregon State University, Weed Science Program. 1998. Table 1. Herbicide classification

according to primary site of action. Oregon State University, Extension, Research, and the Department of Crop and Soil Science. Website: http://www.css.orst.edu/weeds/Publications/table1.html

Panhandle Research Integration for Discovery Education (PRIDE). 2002. Puncturevine,

Tribulus terrestris, Caltrop Family - Zygophylaceae. Website: http://members.aol.com/prideedu/puncturevine.html

Parker, K.F. 1972. An Illustrated Guide to Arizona Weeds. The University of Arizona

Press, Tucson, AZ. 338 pp. this publication and its illustrations are available at:

http://www.uapress.arizona.edu/online.bks/weeds/ Parker, R. 1997. Agrichemicals and their properties. In: William R,D., D. Ball, T.L. Miller,

R. Parker, J.P. Yenish, R.H. Callihan, C. Eberlein, G.A. Lee, and D.W. Morishita, compilers. Pacific Northwest 1997 Weed Control Handbook. Oregon State University, Corvallis, Oregon. p. 12 - 27.

Parker, R. 1997. Control of problem weeds. In: William R,D., D. Ball, T.L. Miller, R.

Parker, J.P. Yenish, R.H. Callihan, C. Eberlein, G.A. Lee, and D.W. Morishita, compilers. Pacific Northwest 1997 Weed Control Handbook. Oregon State University, Corvallis, Oregon. p. 304 -342.

Pathak, P.S. 1970. Contributions to the ecology of Tribulus terrestris Linn. II. Habitat

studies. Agra University Journal of Research Science 19(2):149-166. Ragonese, A. 1955. Plantas toxicas para el ganado en la region central Argentina. Revista

de la Facultad de agronomia, La Plata 31:133-136. Reddi, C.S., E.U. Reddi, and N.S. Reddi. 1981. Breeding structure and pollination ecology of

Tribulus terrestris. Proceedings of the Indian National Science Academy, Part B 47(2):185-193.

Rice, P.M. 2002. INVADERS Database System, University of Montana, Division of

Biological Sciences, Missoula, Montana 59812-4824. Website: http://invader.dbs.umt.edu

Rice, Jr., R.P. 1992. Nursery and landscape weed control manual. Thompson Publications,

Fresno, California. 290 pp. Ridley, H.N. 1930. The dispersal of plants throughout the world. L. Reeve and Co., Ltd.,

Lloyds Bank Buildings, Ashford, Kent. 744 pp. Ross, M.A. and C.A. Lembi. 1985. Applied Weed Science. Macmillan Publishing Company,

New York. 340 pp.

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Sen, D., D. Chawan, and K. Sharma. 1969. Preliminary observations on the influence of

certain weeds on germination and growth of Pennisetum typhoideum Rich. Proceedings of the Indian Academy of Science 60(section B):111-117.

Shreve, F. and I.L. Wiggins. 1964. Vegetation and flora of the Sonoran Desert: Vols. I and

II. Stanford University Press. Stanford, California. 1740 pp. Squires, V.R. 1968. Autoecological studies on Tribulus terrestris L. (Zygophyllaceae). Litt.

B. thesis. University of New England. Squires, V.R. 1969. Ecological factors contributing to the success of Tribulus terrestris L. as

a weed in a winter rainfall environment in southern Australia. Proceedings of the Ecological Society of Australia 4:55-66.

Squires, V.R. 1979. The biology of Australian weeds. 1. Tribulus terrestris L. Journal of the

Australian Institute of Agricultural Science 45(2):75-82. United States Department of Agriculture, Natural Resources Conservation Service. 2001.

The PLANTS database, Version 3.1 (http://plants.usda.gov/plants/). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

University of California. 1998. The Grower's Weed Identification Handbook. Cooperative

Extension University of California, Division of Agriculture and Natural Resources, Publication 4030. 311 pp.

Washington State Noxious Weed Control Board. 2001. Puncturevine (Tribulus terrestris L.).

Website: http://www.wa.gov/agr/weedboard/weed_info/puncturevine.html Whitson, T.D., Editor; L.C. Burrill, S.A. Dewey, D.W. Cudney, B.E. Nelson, R.D. Lee, R.

Parker. 1992. Weeds of the West. The Western Society of Weed Science in cooperation with the Western United States Land Grant Universities Cooperative Extension Services and the University of Wyoming. 630 pp.

Yolo County Resource Conservation District. 2002. Puncturevine, Tribulus terrestris.

Website: http://www.yolorcd.ca.gov/weeds/puncturevine.html

additional sources and websites Cooperative State Research, Education, and Extension Service Website: http://www.reeusda.gov/1700/statepartners/usa.htm This website brings you to an interface to connect with Cooperative Extension programs

throughout the United States; select the desired state, enter a link, often there is a search option in which information on a plant can be searched for.

USDA, Forest Service, Rocky Mountain Research Station, September 2002 has published

'Linking Wilderness Research and Management. Volume 4 - Understanding and Managing Invasive Plants in Wilderness and Other Natural Areas. An Annotated Reading List. General Technical Report RMRS-GTR-79-volume 4 This volume is available on the Web; Website: http://www.fs.fed.us/rm/pubs/rmrs_gtr079_4.pdf (Website: http://www.fs.fed.us/rm/pubs/rmrs_gtr079_4.html provides some information if problems occur in viewing this file)

23

websites with great plant photos:

http://kaweahoaks.com/html/puncture_vine.html

http://www.extension.usu.edu/weedweb/photo/PL.htm then find species and select photos under categories (such as 'plant', 'flower', 'leaf', etc)

http://www.naturesongs.com/vvplants/puncturevine.html

http://courses.smsu.edu/pab532f/IDList6_485.htm scroll down to plant and click on image to enlarge

branches with fruit: http://tncweeds.ucdavis.edu/photos/trite03.jpg

leaves and flower: http://www.calflora.net/bloomingplants/puncturevine.html

http://pi.cdfa.ca.gov/weedinfo/puncturefram.html

http://www.psu.missouri.edu/fishel/puncturevine.htm

http://plnt2012.okstate.edu/plantandseedid/Weeds/Weeds.htm and then click on appropriate name

seeds: http://www.oardc.ohio-state.edu/seedid/ then select species

websites with simple plant descriptions and/or photos:

http://www.agf.gov.bc.ca/cropprot/weedguid/puncture.htm

http://mint.ippc.orst.edu/puncturevine.htm

http://plant.cdfa.ca.gov/biocontrol/weeds/83wbc-tribulus.html

http://www.ipm.ucdavis.edu/PMG/WEEDS/puncturevine.html

some websites with great info:

http://www.naturesongs.com/vvplants/puncturevine.html

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Table 1. Herbicide information for control of puncture vine.

HERBICIDE TRADE NAMES

CHEMICAL GROUP USE MODE OF ACTION IN SOILS NOTES

2,4-D many: some

manufacturers are: Benide, Ortho, Rhone Poulenc, PBI/Gordon, Wilber-Ellis, Agrolinz, Cornbelt, Setre, Lily Miller, Uniroyal, Riverdale, DowElanco, Greenlight

phenoxy Foliar spray or soil

application

Mimic plant's hormones. Absorbed by foliage and translocated symplastically, and accumulates in areas of high metabolic activity (new growth). Primary mode of action not known, but it affects processes such as cell division and elongation.

Salt formulations are subject to leaching in sandy soils; ester formulations are less water soluble so are less likely to leach. Persistence in warm, moist soils average 1 - 4 weeks.

Selective. Many annual and perennial broadleaf species are sensitive. Drift to nontarget sensitive species can be a problem; use a formulation that is less volatile to aid in prevention. (Labeled sites: lawns, golf courses, parks, etc., non-crop land)

amino triazole (amitrole)

Amitrole-T, Amizol triazole Foliar spray Inhibits chlorophyll formation, and regrowth from buds. Slowly absorbed by foliage; some root absorption in sandy soils. Translocated throughout plant in the symplast and apoplast. Plants turn white or pink after treatment.

Limited activity in soils; persists 2-4 weeks. Broken down by microorganisms. Little photodecomposition.

Nonselective; annual and perennial species. Avoid drift, as most desirable plants are sensitive. Apply to actively growing young weeds for best control; do not apply to drought-stressed weeds. (Labeled sites: field nurseries, ornamental plantings, aquatic weeds, forest plantations, non-crop land)

25

atrazine Aatrex, Atrazine, Atra-Pril, Cheat Stop

triazine Soil application or foliar spray

Inhibits photosynthesis. Absorbed primarily through roots with some foliar absorption; apoplastic translocation; readily translocated. Accumulates areas of high metabolic activity (shoot meristems).

Moderate to strong adsorption to soil particles and organic matter. Leaching generally is limited; but may leach in sandy soils, thus groundwater contamination may occur. Seldom found more than 12 in. deep. May persist for more than one season in cold or drought-type soils.

Selective. Selectivity based on resistant plants metabolizing the compound to non-toxic materials; also can be caused by position in soil. Many annual grasses and most broadleaf species sensitive. Most products containing atrazine are restricted-use herbicides. (Labeled sites: conifer nurseries, non-crop land, turf, grass seed production)

bromacil Hyvar X, Hyvar X-L, Krovar

substituted uracil Pre-emergent or spot

treatment

Inhibits photosynthesis. Residual in soils. Relatively mobile in soils.

Nonselective; general vegetation control. Pre-emergent for weeds or during early seedling stage of weed growth. (Labeled sites: no information)

bromoxynil Buctril, Brominal benzonitrile Foliar spray Appears to inhibit photosynthesis and respiration. Absorbed by foliage with little translocation within plant.

Little activity in soils. Selective. Primarily sensitive to annual broadleaf species. Controls some plants species resistant to 2,4-D. Restricted-use herbicide. (Labeled sites: turf)

chlorsulfuron Glean, Telar sulfonyl urea Pre-emergent or foliar spray

Primary mode of action is inhibition of cell division in shoots and root; this is accomplished by interference with the enzyme acetolactate synthase. It is absorbed by foliage and roots, and readily translocated throughout the plant.

Leaches readily in well drained soils, as it is not adsorbed strongly. Subject to hydrolysis (in warm, moist soils of low pH) and microbial degradation in soils, with estimated half-life 4 - 6 weeks.

Selective, when used at low rates. Annual and perennial broadleafs are sensitive. But some broadleaved species are extremely sensitive to this compound at low rates. It has a relatively long soil life. (Labeled sites: non-crop land, roadsides, industrial areas, etc.)

dicamba Banvel, Banvel SGF, Banvel II, Clarity, Trooper, Vanquish

benzoic acid Pre-emergent or foliar spray

Mimic plant's hormones. Absorbed by foliage and roots; readily translocated symplastically and apoplastically throughout plant. Acts as an auxin-like growth regulator. Mechanism not known.

Mobile in soils. Leaches readily. Leaching into root zones of trees, etc., can be a hazard. Decomposition by soil microbes. In warm, moist conditions, half-life is 14 days.

Many annual, biennial, and perennial herbaceous broadleaf species, and some woody species are sensitive. (Labeled sites: home and industrial turf, parks, golf courses, non-crop lands)

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diuron Karmex, Direx substituted urea Pre-emergent or directed foliar spray

Inhibits photosynthesis by inhibiting the Hill reaction. Absorbed mainly by roots, some foliar absorption, and translocated apoplastically through plant.

Adsorbed to soil on organic matter and clays. Leaching is minimal in clay, increases in sandy soils. Persists several months in soil.

Used selectively or as complete vegetation killer. When used at low rates, it can be selective; higher rates for general vegetation control. Requires a surfactant for foliar application (plants must be under 2 in. tall). (Labeled sites: field nurseries, non-crop land)

glyphosate Roundup, Rodeo, Kleenup, Accord, Honcho, Expedite Grass and Weed, E-Z-Ject, Jury, Mirage, Pondmaster, Protocol, Rattler, Ruler, Silhouette

glycine derivative Foliar spray Absorbed by foliage and translocated symplasticly to sites of high metabolic activity in roots and shoots. Inhibits amino acid synthesis. May be washed off if rain occurs within 6 hours.

Strongly adsorbed to soil and inactivated. Little leaching, no soil activity. Broken down by microorganisms.

Nonselective. Low volume applications most effective. May be washed off if rain occurs within 6 hours. Rhizome kill often best when applied to mature weeds at time of flowering. Rodeo and Accord require additional nonionic surfactant. Grass control enhanced with addition of ammonium sulfate to spray solution. Retreatment may be necessary. (Labeled sites: turf renovation, nurseries, parks, home garden, industrial landscapes)

MCPA many: some manufacturers are: Rhone-Poulenc, Lilly Miller, Wilber-Ellis, Agrolinz, Inter-Ag Corp.

phenoxy Foliar spray or soil

application

Mimic plant's hormones. Absorbed by foliage and translocated symplastically, and accumulates areas of high metabolic activity (new growth). Primary mode of action not known, but it affects processes such as cell division and elongation.

Readily leached in soils. Rapid decomposition by soil microbes; low photodecomposition rate. Persistence in soils under moist conditions is 1 month, in dry conditions is 6 months.

Selective. Many broadleaf species sensitive. (Labeled sites: turf, non-crop lands)

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MSMA Arsonate, Daconate, Trans-Vert, Bueno, Ansar, Weed-hoe, Weed-E-Rad,

Organic arsenical Foliar spray Unknown. Suspected to replace phosphorus and interferes with biochemical processes; such as production of ATP. May also interfere with enzyme activity and disrupt membranes. Absorbed through foliage, and translocated symplastically.

Strongly adsorbed in soil. Behaves like phosphate in soil. Resists leaching, but can accumulate.

Limited selectivity. Annual and perennial grasses and some annual broadleaf species sensitive. Best results obtained when air temperature above 80 degrees F. (Labeled sites: turf, non-crop, landscapes)

norflurazon Solicam, Evital, Zorial, Predict

pyridazinone Pre-emergent. Aqueous

solution used as soil drench.

Inhibits synthesis of carotenoid pigments. In absence of these pigments, chlorophyll is decomposed. Absorbed by roots and translocated to sites of high metabolic activity. Chlorosis occurs.

Adsorbed by organic matter. Does not leach appreciably. Broken down by microorganisms and by photodegradation and volatilization on soil surface.

Selective. Incorporate within 4 weeks of application. (Labeled sites: orchards, non-crop land)

oryzalin Surflan, Weed Stopper, Weed & Grass Preventer

dinitroaniline Soil application

Inhibits seed germination and root development; mitosis. Little absorption. Severely inhibits root development. Little to no foliar activity; and is not translocated through plant.

Adsorbed in soil. Leaching can occur. Decomposed by microbes and some photodecomposition. Slightly volatile.

Used selectively. Most seedling grasses and some annual broadleaf species sensitive. Kills germinating seedlings, not established plants. (Labeled sites: no information)

oxyfluorfen Goal diphenyl ether Pre-emergent or foliar spray

Disrupts cell permeability. Absorbed mainly through the shoot (meristematic). Little absorption by roots and translocation occurs in plant.

Strongly adsorbed in soil. Leaching is minimal. Not readily decomposed by microbes or photodecomposition.

Selectivity occurs by compound placement. Requires light for herbicidal activity if applied to foliage. (Labeled sites: no information)

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paraquat Gramonxone, Ortho Paraquat CL

bipyridylium salt Foliar spray Disrupts membranes. High energy free radicals formed by paraquat in plant responsible for herbicidal activity. Rapidly absorbed by foliage and sometimes may be translocated in xylem.

Strongly adsorbed in soil. Is persistent and biologically unavailable.

Non-selective. All annual species, top kill of perennials. Use non-ionic surfactant. Thorough coverage important. Toxic to mammals. Restricted-use herbicide. (Labeled sites: non-crop land, nurseries. Not for use in parks, playgrounds, home gardens, schools)

picloram Tordon picolinic acid Foliar spray or soil

application

Mimic plant's hormones. Rapidly absorbed by foliage and roots and translocated symplastically and apoplastically to accumulate in areas of high metabolic activity (new growth).

Is highly mobile in soil, with average persistence being two to several seasons after application, depending on application rate and climate.

Restricted-use herbicide. Highly phototoxic. Many woody plants, and most annual and perennial herbaceous broadleaved plants are susceptible. Most grasses are resistant. Careful precautions must be made to prevent injury to desired plants. Because of persistence in soils, chances of contamination in non-treated areas must be considered. Do not apply in areas where compound can leach into root zone of susceptible species, or into water supplies. (Labeled sites: no information)

simazine Princep, Aquazine, Caliber 90, Gesatop, Simazine

triazine Soil application

Inhibits photosynthesis. Readily absorbed by roots (little foliar activity), and translocated apoplastically through plant to roots and shoots.

Moderate to strong adsorption to soil particles and organic matter. Leaching generally is limited; but may leach in sandy soils. Little lateral movement. Decomposition by soil microbes. May persist for considerable periods of time depending on soil conditions and application rates.

Used selectively or as complete vegetation killer. When used selectively, primarily annual grasses and broadleaf species sensitive. Activation requires considerable soil moisture. Long residual action. Carryover to susceptible species can occur. Resistance has been reported. (Labeled sites: no information)

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tebuthiuron Spike, Sprakil substituted urea pre- or post- emergent

Inhibits photosynthesis. Absorbed primarily through roots with some foliar absorption; readily translocated.

In dry soils (those receiving less than 40-60 inches per year) persistence is considerable; half-life in wetter soils 12-15 months. No significant lateral movement, nor more than 12 inches deep with surface application.

General vegetation control: including most woody plants. Caution should be taken due to long residual life and strong herbicidal properties. (Labeled sites: non-crop land)

trifluralin Treflan, Trifluralin, Ornamental Weeder, Trilin 5

dinitroaniline Soil application

Inhibits mitosis. Microtubule assembly inhibitor. Severely inhibits root development. Little to no foliar activity; and is not translocated through plant.

Strongly adsorbed in soil. Leaching is minimal. Decomposed by microbes or photodecomposition. Slightly volatile. Half life is about 2 months.

Used selectively. Most seedling grasses and some annual broadleaf species sensitive. Kills germinating seedlings, not established plants. Requires soil incorporation after application. Residual activity and carryover to sensitive species possible when used at higher than normal rates. Toxic to fish. (Labeled sites: no information)

This information compiled from ExToxNet (2002), Oregon State University, Weed Science Program (1998), Parker (1997), Rice (1992), Ross and Lembi (1985).