Source: California Invasive Plant Council
URL of this page: http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=72&surveynumber=182.php
Invasive Plants of California's Wildland
|Scientific name||Schinus terebinthifolius|
|Additional name information:||Raddi|
|Common name||Brazilian pepper tree, Christmas-berry tree, Christmasberry, Florida holly|
|Synonymous scientific names||Schinus mucronulata, S. antiarthriticus|
|Closely related California natives||0|
|Closely related California non-natives:||Schinus molle|
|Listed||CalEPPC List B,CDFA nl|
HOW DO I RECOGNIZE IT?
Brazilian pepper tree (Schinus terebinthifolius) is a many-stemmed shrub or small tree. Its branches form a nearly impenetrable tangle down to ground level. The flowers are small, less than one-tenth of an inch in diameter, and have five green-tinged, white petals. The tree is covered with round, bright red fruit from December to February. The odd-pinnate compound leaves have a narrowly winged rachis and rounded, often toothed leaflets that give off a strong smell of turpentine when crushed (Tomlinson 1980).
|WHERE WOULD I FIND IT?||
While it can be found in Santa Clara County in northern California, Brazilian pepper tree is far more common and problematic in southern California from Riverside to the coast, including Ventura and San Diego counties. Usually it is found below 200 meters elevation, especially in canyons and washes (Hickman 1993). Brazilian pepper is capable of surviving a broad range of hydrologic conditions, but does best in well drained sites (Ewel 1979). This species is a pioneer of disturbed sites, such as highway rights-of-way, fallow fields, and drained bald cypress stands. It can also establish in undisturbed wildlands (Woodall 1982). It causes severe problems in southern Florida, where it invades pinelands, mangrove forests, and marshes, and it is a major invader in croplands under restoration in Everglades National Park.
|WHERE DID IT COME FROM AND HOW IS IT SPREAD?||
Brazilian pepper tree is native to Argentina, Paraguay, and Brazil, where it occupies dry savannah (Nilsen et al. 1980). It is a sparsely distributed species in its native range, where it rarely acquires the dominance that it achieves in California and other areas in which it has become naturalized. It was introduced into Florida in 1891 as an ornamental, although there is evidence that it arrived in the United States fifty years earlier (Gogue et al. 1974). It is still used as an ornamental in California, Texas, and Louisiana. Other than escaping from human cultivation in gardens, Brazilian pepper tree spreads via small mammals and birds, especially robins, which eat the drupes and then distribute the seeds during their travels. Mammals such as raccoons and possums consume the fruits and deposit the seeds with fecal materials, giving the seeds a nutrient-rich microsite in which to establish (Ewal et al. 1982). This species has infiltrated the islands of Hawaii, Bermuda, and the Bahamas, as well as Florida and, more recently, California. In addition to spreading by seed dispersal, it can resprout, especially after fire (Elfers 1995).
|WHAT PROBLEMS DOES IT CAUSE?||
Outside its native home, Brazilian pepper tree spreads aggressively. Typically, dense monospecific stands form within a few years after trees invade an area. This often creates a dense canopy and can shade out most competing vegetation, posing a serious threat to natural vegetation and organisms that depend on them (Bennett et al. 1988, Doren and Whiteaker 1990, Ewel 1979). The tenacity of Brazilian pepper seedlings impairs competition by native vegetation. Brazilian pepper also seems to produce allelopathic chemicals in the soil that inhibit growth of other plants (Bennett et al. 1988). The plant is moderately salt tolerant, withstands flooding, fire, and drought, and resprouts quickly after being cut. Its ability to resprout and grow rapidly allows it to quickly dominate burned areas.
|HOW DOES IT GROW AND REPRODUCE?||
Brazilian pepper tree reproduces by seed. Flowering begins in September, and by mid-October almost every tree is in flower. Most flowering ceases in early November. A small fraction of the population flowers in March-May. Fruit ripening follows close behind flowering, with most occurring between December and February (Ewel et al. 1982). Mature female trees are prodigious seed producers, which, combined with a viability rate of 30 to 60 percent, results in a vast number of seedlings (Elfers 1995). It has been suggested that female flowers may mimic male flowers, attracting foragers in search of pollen (Ewel et al. 1982). Fruit production occurs in winter (November to February), at which time the branches of female trees are heavily laden with red fruits.
Ripe fruits are retained on the tree for up to eight months, and all are dispersed before the next flowering season (Ewel et al. 1982). The attractive fruits are readily eaten and transported by birds and mammals, with water and gravity serving as less important dispersal agents. Seed dispersal by native and exotic birds, such as catbirds, mockingbirds, American robins, and red-whiskered bulbuls, accounts for the presence of Brazilian pepper tree in almost every terrestrial plant habitat in southern Florida (Austin 1978, Ewel et al. 1982, Ewel 1986). Robins, when present, are believed to consume and transport more Brazilian pepper tree seed than all other dispersal agents combined. Raccoons and possibly possums are known to ingest the fruits (Ewel et al. 1982). The fact that little else is fruiting during the winter months when Brazilian pepper tree seeds are dispersed has been suggested as a possible explanation for the success of this plant in southern Florida (Ewel 1986).
Seeds are generally not viable beyond five months after dispersal. However, Ewel (1979) reported seed germination in late fall. Under certain conditions; seeds apparently retain their viability during the wet season and germinate when water levels drop later in the year.
Most seed germination takes place between January and February, but the range is from November to April. Seeds germinate within about twenty days. Seedlings have been found to grow quickly in most young successional communities and slowly in most older communities. Well watered conditions favor germination. Survival of Brazilian pepper tree seedlings, even of mature forest trees, is 66 to 100 percent (Ewel 1986). Ewel et al. (1982) concluded that the growth plasticity of Brazilian pepper tree seedlings makes this species especially difficult to manage. Seedlings can grow slowly under the dense shade of mature stands and then exhibit vigorous growth when the canopy is opened after a disturbance. In exposed, open areas, such as young successional communities, their growth rate is as high as twelve to twenty inches (30-50 cm) per year.
Under favorable growing conditions, Brazilian pepper tree can reproduce within three years after germination. This species can occur individually or as extensive stands; in areas with warm, tropical conditions, it occurs primarily in dense stands.
|HOW CAN I GET RID OF IT?||
The severity of the problem is an important consideration when designing a control strategy for Brazilian pepper tree. In many cases, it is unrealistic to attempt eradication where this species is widespread; instead the goal should be to prevent colonies from establishing new infestations. Because this species is an invasive, habitat-altering weed in other states, especially Florida, research on control techniques has been underway for some time (Elfers 1995). With all control and removal techniques, a lack of sprouting for one or even two years may not guarantee that the sprouting potential of the roots is exhausted. Yearly monitoring for at least three years following control efforts is recommended. Monitoring should occur in late spring to determine if any shoots have survived or any resprouting has occurred in treated areas.
Manual/mechanical methods: Entire saplings, including root systems, can be pulled up by hand, but by the time the plant is several feet tall, hand pulling may be impossible. If as much as one-quarter of the root system is left in the ground, the plant may resprout. Using heavy equipment such as bulldozers, the entire plant, including the root system, can be removed.
Soil removal: A study in south Florida found that removing soil with a bulldozer down to the limestone bedrock effectively prevented the return of Brazilian pepper tree. It also stimulated the growth of a diversity of plant species. However, this site had little or no soil before it was rock-plowed and farmed, so removing the soil was part of a logical restoration program. Removing soil can also stimulate the growth of non-natives that thrive in disturbed areas.
Prescribed burning: Results of burning were mixed. Because they cannot tolerate heat, Brazilian pepper tree seeds will not germinate following fire, although basal trunk and root sprouting is aggressive. Once saplings attain a height of one meter, most are able to survive fire by regrowth from the roots. Since it can grow more rapidly than competing native hardwoods, Brazilian pepper tree can establish or reestablish dominance (Loope and Dunevitz 1981). Repeated burning does not prevent this plant from reinvading an area in which it was previously dominant (Doren and Whiteaker 1990).
Insects and fungi: No USDA biological control agents have yet been approved by the USDA, but research is underway, especially in the heavily infested states of Florida and Hawaii. In 1988 a seed-eating wasp, Megastigmus transvaalensis, was reared on Brazilian pepper tree fruit collected from Palm Beach, Florida. Part of the controversy surrounding the development of plant-eating fauna for this species is the concern that insects that attack Schinus terebinthifolius will also attack the closely related S. molle, a common ornamental. A study in Hawaii reported that a caterpillar, Epsismus utilis and a beetle, Bruchus atronotatus, had the potential to limit seed production, but field tests found that these insects did not significantly control the plant (Clausen 1978).
Triclopyr (as Garlon 3-A®), applied at 100 percent and using the frill-cut method, has been shown to kill mature trees and prevent regrowth. Depending on the setting, it may be advantageous to cut down the trees down and then apply herbicide to the stumps to prevent regrowth (Bily, pers. comm.).
Successful treatments for full-sized plants also include basal spot applications of bromacil and hexazinone, which kill by blocking photosynthesis. For widely scattered plants, where access to the main stem is difficult, basal spot treatments are easily applied and effective. Bromacil and hexazinone are selective, so nearby vegetation is not harmed. Since Brazilian pepper tree’s transpiration rate per unit leaf area is unusually high, and since it generally occupies an emergent canopy position, it acts as a strong sink for soil-applied herbicides, thus minimizing leaching losses and off-target damage. When it is growing in the shade of other plants, this generalization does not hold (Woodall, 1982).
Foliar herbicides are the fastest acting with the least residual activity, although their probability of success is relatively low. Foliar herbicides that have been used with some success include 15 percent triclopyr (as Garlon 3A®) diluted with water or diesel, 2 percent triclopyr (as Garlon 4) diluted with water, and 2 percent dicamba (as Banvel 720®) diluted with water. Ammonium-sulfate and glyphosate are also foliage absorbed. All of these herbicides are most effective when applied to seedlings. The only herbicide that resulted in consistently killed roots as well as shoots was picloram (Woodall 1982), but this is not currently registered for use in California.