Ailanthus altissima

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Author: Marc C. Hoshovsky, Global Invasive Species Team, The Nature Conservancy

Contents


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Taxonomy
Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Order: Sapindales
Family: Simaroubaceae
Genus: Ailanthus
Species: A. altissima
Scientific Name
Ailanthus altissima
(P. Mill.) Swingle
Scientific Name Synonym
Ailanthus glandulosa
(P. Mill.) Swingle
Common Names

tree-of-heaven, tree of heaven, ailanthus, copal tree, stinking shumac, varnish tree, Chinese sumac, paradise-tree

Overview

Appearance
Ailanthus altissima is a rapidly growing, typically small tree up to 80 ft. (24.4 m) in height and 6 ft. (1.8 m) in diameter. It has large leaf scars on the twigs.
Foliage
Foliage is one of the best identifying characteristics for this species. The leaves are pinnately compound and 1-4 ft. (0.3-1.2 m) in length with 10-41 leaflets. Ailanthus altissima resembles native sumac and hickory species, but it is easily distinguished by the glandular, notched base on each leaflet.
Flowers
Species is dioecious and flowering occurs in early summer when large clusters of yellow flowers develop above the foliage.
Fruit
Fruit produced on female plants are tan to reddish, single winged and can be wind or water-dispersed.
Ecological Threat
Ailanthus altissima forms dense, clonal thickets which displace native species and can rapidly invade fields, meadows, and harvested forests. This invasive tree species is extremely tolerant of poor soil conditions and can even grow in cement cracks. Ailanthus altissima is not shade tolerant, but easily invades disturbed forests or forest edges causing habitat damage. Introduced as an ornamental, it was widely planted in cities because of its ability to grow in poor conditions. Management and control efforts for this species continue across the United States at great economic cost.

Stewardship summary

Ailanthus is a fast growing tree, a prolific seed producer, a persistent stump and root sprouter and an aggressive competitor with respect to the surrounding vegetation. It occurs primarily in disturbed areas, though it may invade undisturbed habitats. It was brought into California mainly by the Chinese who came to California during the goldrush in the 1890's, and frequently occurs in abandoned mining sites. Little work has been done on developing biological or chemical control methods. The most effective means of control may be to pull seedlings by hand before the tap root develops.

Natural history

Range

In the Americas, Ailanthus occurs from Canada to Argentina. Native to China. Also escaped in Europe.

Habitat

Ailanthus is native to central China, where its history is as old as the written language of the country.[1] Little information is available on its ecology in China, although Hu (1979)[1] reviews its cultural importance and value for wood products and medicine.

The species was apparently introduced into America by two different routes. The first route began with Pierre d'Incarville mistaking it for the lacquer tree in China and sending seeds to England around 1751.[1][2] It was then introduced to America by a Philadelphia gardener in 1784.[1] Because of its rapid growth and ability to grow in unfavorable conditions with little care, it became a common stock in eastern nurseries by 1840. The second route was through Chinese miners. During the days of the California gold rush, many Chinese miners brought Ailanthus seeds with them as they settled in California, probably because of its medicinal and cultural importance to them.

Escaping from cultivation and quickly becoming established on both coasts, Ailanthus has expanded its range considerably since its initial introductions. Specimens from the Harvard University Herbarium indicate that it "runs wild from Massachusetts...to Oregon ... and from Toronto, Canada ... to Argentina ...".[1] In some localities Ailanthus is so well established that it appears to be a part of the native flora.[3]

In the eastern United States, the frequency of Ailanthus occurrences increases as one nears the cities. In neglected urban areas, Ailanthus grows "as trees close to buildings, as hedges, or as bushy aggregates along railroad tracks, highway embankments, walls at the ends of bridges and overpasses, or in cracks of sidewalks and along fences".[1] Although it is usually found in disturbed areas, it occasionally spreads to undisturbed areas. Kowarik (1983)[4] views human settlements as centers of its distribution and roads as migration routes.

In California Ailanthus is widely naturalized in cismontane areas, especially around old dwellings and mining settlements.[5] It has become established in Pleasants Valley, Solano and Marin counties, Berkeley, Vacaville, Petaluma, San Andreas, Angel's Camp, Columbia, and in various places in the Sacramento Valley.[6]

Ecology

Although Ailanthus is sensitive to frost damage during its early years[7], 6-year-old trees have survived winters of -33 centigrades accompanied by high winds.[8] Although Koffer (1895)[9] suggested that Ailanthus was unable to withstand the prolonged dry seasons of the Midwest, Dubroca and Bory (1981)[10] commented on the "drought resistance" of the species. Dry soils are probably more suitable for its growth than wet soils.[7]

Ailanthus does well on very poor soils. Adamik and Brauns (1957)[7] cultivated the species on rather thin topsoil and it "thrives even on stony ground." The tree has been used in revegetating acid mine spoils, tolerating a pH of less than 4.1, soluble salt concentrations up to 0.25 mmhos/cm and phosphorus levels as low as 1.8 ppm.[11] The tolerance of Ailanthus to soil salinity is a disputed point in the literature. Opinions range from "salty soils not suitable for growth" [7] to Ailanthus "growing well on very saline shell sands.[12] Intermediate views are expressed by Brogowski et al. (1977)[13], Semoradova and Materna (1982)[14] and Zelenin (1976)[8].

Ailanthus has been planted widely in urban areas because of its ability to tolerate atmospheric pollution. Its ability to adapt to "the dirt and smoke, the dust and drought of cities" was recognized nearly 100 years ago.[15] More recently Ailanthus has been observed to survive cement dust near cement and lime works [16]; it is moderately resistant to fumes produced by the coke and coal-tar industry [17]; its leaves absorb significant amounts of sulfur in areas of high traffic flow [18]; it can accumulate high levels of mercury in its tissues [19]; and it is somewhat resistant to ozone exposure.[20]

Although Ailanthus may suffer from root competition by other trees already established in an area[21], usually it competes successfully with other plants [21][1] and is considered a "dangerous weed" in forest plantations.[22] A high degree of shade tolerance gives Ailanthus a competitive edge over other plant species.[23] The production of toxic chemicals by Ailanthus may also explain the success of this plant. An aqueous extract of Ailanthus leaves has been shown to be toxic to 35 species of gymnosperms and 10 species of angiosperms.[24] This may be important in limiting natural succession in Ailanthus stands. The toxicity levels are highest in the leaves during the early part of the growing season and are maintained at high levels at least until October (Voigt and Mergen 1962).

Reproduction

Ailanthus reproduces both sexually and asexually. Asexual reproduction is by vegetative sprouting from stumps or root portions.[1] Flowering occurs rather late in the spring (June). Ailanthus has the longest winter dormancy of all the trees in its native Chinese habitat.[1] Precocious flowering is not a rare occurrence in this species and has been observed in seedlings only 6 weeks after germination.[25]

Seeds ripen in large crowded clusters from September to October of the same year and may persist on the tree through the following winter.[3][1] An individual tree can produce 325,000 seeds per year which are easily wind-dispersed.[26] These seeds average over 30,000 per kilogram. This amount yields up to 6-7000 "usable plants".[3] Limited testing of Ailanthus seeds indicate that they have dormant embryos, and that germination is benefited by stratification on moist sand for 60 days at 41°F.[3]

Seedlings establish themselves rapidly by producing a well formed tap root in less than three months.[7] In more compacted soils these seedlings put forth long rope-like lateral roots to exploit a greater soil volume.[27] Ailanthus grows quickly in full sunlight and averages a meter of growth in height per year for at least the first four years.[7] The trees may grow to 15-20 meters tall but have a rather short lifespan of less than 50 years.[28]

Impacts

Although only occasionally found in nondisturbed areas [4], Ailanthus is a prolific seed producer, grows rapidly and can successfully compete with the native vegetation. It produces toxins which prevent the establishment of other species. [24]The root system is aggressive enough to cause damage to sewers and foundations.[1]

Ailanthus was not nominated by any specific preserve manager, but is recognized by TNC staff as an important exotic weed. A recent survey (2 March 1985) of CNPS members showed a wide distribution of this tree throughout California. Members of both the Mt. Lassen and Sequoia chapters consider it a major pest at low elevations. There are also reports of it growing in Santa Cruz, Riverside, San Bernardino, Los Angeles and San Diego counties.

Management/Monitoring

Although only occasionally found in nondisturbed areas [4], Ailanthus is a prolific seed producer, grows rapidly and can successfully compete with the native vegetation. It produces toxins which prevent the establishment of other species.[24] The root system is aggressive enough to cause damage to sewers and foundations.[1]

Ailanthus was not nominated by any specific preserve manager, but is recognized by TNC staff as an important exotic weed. A recent survey (2 March 1985) of CNPS members showed a wide distribution of this tree throughout California. Members of both the Mt. Lassen and Sequoia chapters consider it a major pest at low elevations. There are also reports of it growing in Santa Cruz, Riverside, San Bernardino, Los Angeles and San Diego counties.

Weed control involves three fundamental objectives: prevention, eradication and control.

From a practical viewpoint, methods of weed management are commonly categorized under the following categories: physical, thermal, managerial, biological, and chemical.[29] Physical methods include both manual and mechanical methods. Thermal methods include both broadcast burning or spot treatment with a flame thrower. Managerial methods include the encouragement of competitive displacement by native plants and prescribed grazing. Biological control is usually interpreted as the introduction of insects or pathogens which are highly selective for a particular weed species. Chemical control includes both broadcast and spot application.

The most desirable approach is that of an integrated pest management plan. This involves the optimum use of all control strategies to control weeds. This approach is generally accepted as the most effective, economical, and environmentally sound long-term pest control strategy.[29] In cases where more than one control technique is used, the various techniques should be compatible with one another. Broadcast herbicide application, for example, may not work well with certain managerial techniques (i.e., plant competition).

Physical control

The two types of physical control methods discussed below, manual and mechanical, produce slash (i.e., cutting debris) that can be disposed of by several techniques. If cut before seeds are produced it may be piled and left for enhancement of wildlife habitat (i.e., cover for small mammals). Debris may be fed through a mechanical chipper and used as mulch during revegetation procedures. Care should be taken to prevent vegetative reproduction from cuttings. Burning the slash piles is also effective in disposing of slash.

Manual control

Manual methods use hand labor to remove undesirable vegetation. These methods are highly selective and permit weeds to be removed without damage to surrounding native vegetation.

Hand Pulling

Ailanthus is probably best controlled by manual removal of young seedlings. Seedlings are best pulled after a rain when the soil is loose. This facilitates removal of the rooting system, which may resprout if left in the ground. After the tap root has developed, this would be extremely difficult. Plants should be pulled as soon as they are large enough to grasp but before they produce seeds.

The Bradley Method is one sensible approach to manual control of weeds.[30] This method consists of hand weeding selected small areas of infestation in a specific sequence, starting with the best stands of native vegetation (those with the least extent of weed infestation) and working towards those stands with the worst weed infestation. Initially, weeds that occur singly or in small groups should be eliminated from the extreme edges of the infestation. The next areas to work on are those with a ratio of at least two natives to every weed. As the native plant stabilizes in each cleared area, work deeper into the center of the most dense weed patches. This method has great promise on nature reserves with low budgets and with sensitive plant populations. More detailed information is contained in Fuller and Barbe (1985)[30].

Cutting

Manually operated tools such as brush cutters, power saws, axes, machetes, loppers and clippers can be used to cut Ailanthus . This is an important step before many other methods are tried, as it removes the above-ground portion of the plant. For thickly growing, multi-stemmed shrubs and trees, access to the base of the plant may not only be difficult but dangerous where footing is uncertain.

Hand Digging

The removal of rootstocks by hand digging is a slow but sure way of destroying weeds which resprout from their roots. The work must be thorough to be effective as every piece of root that breaks off and remains in the soil may produce a new plant. Such a technique is only suitable for small infestations and around trees and shrubs where other methods are not practical.

Girdling

Girdling involves manually cutting away bark and cambial tissues around the trunks of undesirable trees such as Ailanthus. This is a relatively inexpensive method and is done with an ordinary ax in the spring when the trees are actively growing. Hardwoods are known to resprout below the girdle unless the cut is treated with herbicides. Although it may be undesirable to leave standing dead trees in an area, this technique has been shown to reduce stump sprouting in live oaks, and may be a useful technique for controlling Ailanthus.

Mechanical control

Mechanical methods use mechanized equipment to remove above ground vegetation. These methods are often non-selective in that all vegetation on a treated site is affected. Mechanical control is highly effective at controlling woody vegetation on gentle topography with few site obstacles such as rocks, stumps or logs. Most mechanical equipment is not safe to operate on slopes over 30 percent. It is also of limited use where soils are highly susceptible to compaction or erosion or where excessive soil moisture is present. Site obstacles such as rocks, stumps or logs also reduce efficiency.

Chopping, cutting or mowing

Saplings may be trimmed back by tractor-mounted mowers on even ground or by scythes on rough or stony ground. Unwanted vegetation can be removed faster and more economically in these ways than by manual means and with less soil disturbance than with scarification. However, these methods are nonselective weed eradication techniques. They reduce the potential for biological control through plant competition and open up new niches for undesirable vegetation. In addition, wildlife forage is eliminated.

Saplings usually require several cuttings before the underground parts exhaust their reserve food supply. If only a single cutting can be made, the best time is when the plants begin to flower. At this stage the reserve food supply in the roots has been nearly exhausted, and new seeds have not yet been produced. After cutting or chopping with mechanical equipment, Ailanthus resprouts from root crowns in greater density if not treated with herbicides.

Prescribed burning

A flame thrower or weed burner device can be used as a spot treatment to heat-girdle the lower stems of small trees. This technique has advantages of being less costly than basal and stem herbicide treatments and is suitable for use during wet weather and snow cover. Ailanthus resprouts after heat-girdling.[21]

Managerial control

In most cases Ailanthus prevents the establishment of other native plants and must be initially removed. Following physical or thermal removal of mature plants, root crowns must be treated to prevent resprouting. Seedlings of native plant species usually cannot establish fast enough to compete with sprout growth from untreated stumps. Ailanthus is shade tolerant, so presumably can and will sprout under other plants.

Prescribed grazing

The continued removal of the tops of seedlings and resprouts by grazing animals prevents seed formation and also gradually weakens the underground parts. Grazing must be continued until the seedbank is eliminated, as the suppressed plants return quickly after livestock is removed and begin to dominate pastures again.

Biological control

The term "biological control" is used here to refer to the use of insects or pathogens to control weeds. The introduction of exotic natural enemies to control plants is a complex process and must be thoroughly researched before implementation to prevent biological disasters. Such tools are not normally suitable for preserve managers to implement.

Biological control of Ailanthus has not been addressed to any extent beyond the anecdotal stage. No susceptibilty of Ailanthus to parasites was found or noticed in Austrian nurseries.[7] French (1972)[31] notes that the zonate leafspot (Cristulariella pyramidalis) causes defoliation of Ailanthus in Florida. In India, Atteva fabricella is considered an Ailanthus defoliator [32] and Italian seedlings, weakened by cold, were weakly parasitized by the fungus Placosphaeria spp. (Magnani 1975).

Chemical control

Methods of chemical control of Ailanthus are poorly explored in the literature. Detailed information on herbicides in general is available in such publications as Weed Science Society of America (1983)[33]. The Weed Science Society reference gives specific or USDA (1984) information on nomenclature, chemical and physical properties of the pure chemical, use recommendations and precautions, physiological and biochemical behavior, behavior in or on soils and toxological properties for several hundred chemicals. Comprehensive coverage of this information will not be presented in this Element Stewardship Abstract. In applying herbicides it is recommended that a dye be used in the chemical mixture to mark the treated plants and thus minimize waste.

The following discussion highlights herbicide application methods which may be useful in controlling Ailanthus us. Herbicides may be applied non-selectively (i.e., broadcast applications) or selectively (i.e., spot applications). Both types of applications have advantages and disadvantages and will be discussed separately.

Broadcast Herbicide Application

In general, when using broadcast application methods, plants should be sprayed only when in full leaf. Results are poor prior to full leaf development. The best results have been obtained when plants are in the fruiting stage in late summer or early autumn.[34]

Kolarvskij (1967) reports that 2,4-D can stop seedling growth in Ailanthus , and Sterrett et al. (1971)[35] found that a mixture of 2- chloroethyl phosphoric acid and potassium iodide gives 80-100% defoliation of Ailanthus within 3 weeks.

Spot Chemical Methods

Spot chemical methods consist of various techniques for manually applying herbicides to individual plants or small clumps of plants (such as stump resprouts). These methods are highly selective as only specific plants are treated. They are most efficient when the density of stems to be treated is low.

Jones and Stokes Associates (1984)[36] reviewed a variety of spot chemical techniques. The following is an excerpt from this report, listing techniques in order of increasing possibility of herbicide exposure to the environment or to humans in the vicinity of treated plants.

1) Stem injection: Herbicides are injected into wounds or cuts in the stems or trunks of plants to be killed. The herbicide must penetrate to the cambial tissue and be water-soluble to be effective. The chemical is then translocated throughout the tree and can provide good root-kill, and thus prevents resprouting.

2) Cut stump treatment: Herbicides are directly applied to the cambial area around the edges of freshly cut stumps. Application must occur within 5-20 minutes of cutting to ensure effectiveness. McHenry (1985)[37] suggests late spring as the best season to do this. In early spring sap may flow to the surface of the cut and rinse the chemical off. At other times of the year translocation is too poor to adequately distribute the chemical. Applications may be made with backpack sprayers, sprinkling cans, brush and pail, or squeeze bottles. This treatment is effective in killing root systems of sprouting hardwoods. Picloram should not be used for this technique as it is known to "flashback" through root grafts between treated and untreated plants and may damage the untreated individuals. Tre-Hold, an asphalt based formulation containing 1% NAA ethylester has been used as a sprout retardant on Ailanthus with varying degrees of effectiveness.[38]

3) Basal/Stem sprays: High concentrations of herbicides in oil or other penetrating carriers are applied, using backpack sprayers, to the basal portion of stems to be killed. The oil carrier is necessary for the mixture to penetrate bark and enter the vascular system. This method gives good root kill, especially in the fall when vascular fluids are moving toward the roots. This method may be easier to use with small diameter stems than the two previous techniques.

4) Herbicide pellets: Pelletized or granular herbicides are scattered at the bases of unwanted plants. Subsequent rainfall dissolves the pellets and leaches the herbicide down to the root system. Optimal time for treatment is towards the end of the rainy season to prevent leaching beyond the root zone.

Management

Programs

Tim Thomas (1985)[39] has removed a small stand of Ailanthus in the Santa Monica Mountains National Recreation Area, by pulling up young saplings and is currently monitoring the site to see if it resprouts.

Contact: Tim Thomas, Park Ranger, Santa Monica Mountains National Recreation Area 22900 Ventura Blvd. Woodland Hills, CA 91364, (213) 888-3440.

Monitoring Requirements

Monitoring is needed to determine the presence of ailanthus on or near preserves.

Research

What types of undisturbed habitats does it invade? How do native species respond to Ailanthus toxins, and how is recovery potential of an area previously occupied by Ailanthus affected by these toxins? What is the chemical make-up of these toxins? What can be used to buffer the effects of the toxins so that understory native seedling growth is encouraged? At what age is the tap root so long that it precludes Ailanthus removal by hand?

Presentation Materials

These materials may be used as long as the original author is given credit.

Tree of Heaven

Resources

Information sources

Bibliography

  1. Hu, S. Y. 1979. Ailanthus. Arnoldia 39(2):29-50. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11
  2. Feret, P. P. and R. L. Bryant. 1974. Genetic differences between American and Chinese Ailanthus seedlings. Silvae Genetica 23(5):144-148.
  3. Little, S. 1974. Ailanthus altissima. In C. S. Schopmeyer (ed.), Seeds of Woody plants in the United States. USDA Forest Service Agriculture Handbook No. 450. 3.0 3.1 3.2 3.3
  4. Kowarik, I. 1983. The acclimatizaiton and phytogeographical behavior of the tree of heaven (Ailanthus altissima) in the French Mediterranean area (Bas-Langvedoc). Phytocoenologia 11(3): 389-406. 4.0 4.1 4.2
  5. Munz, P.A., and D.D. Keck. 1973. A California flora and supplement. Univ. California Press, Berkeley, CA.
  6. Robbins, W. W., M. K. Bellue, and W. S. Ball. 1951. Weeds of California. California Dept. Agric., Sacramento.
  7. Adamik, K. J. and F. E. Brauns. 1957. Ailanthus glandulosa (tree of heaven) as a pulpwood. Part II. Tappi 40(7):522-527. 7.0 7.1 7.2 7.3 7.4 7.5 7.6
  8. Zelenin, A. V. 1976. [Afforestation of saline soils in the Sal'skaya steppes]. Lesnoe Khozyaistro 9:79-81 (in Russian). 8.0 8.1
  9. Koffer, C. A. 1895. Trees of minor importance for western planning. Gorden and Forest. 8:122-123.
  10. Dubroca, E. and G. Bory. 1981. [Carbohydrate and nitrogen compounds and resistance to drought in Ailanthus altissima]. Biochem Syst. Ecol 9(4):283-288 (in French)
  11. Plass, W. T. 1975. An evaluation of trees and shrubs for planting surface mine spoils. USDA For. Serv. N. E. For. Exper. Stat. Res. Paper N. E. 317. 8 pp.
  12. Lavrinenko, D. D. and F. I. Volkov. 1973. [Salt resistance of species on the coast of the Sea of Azov]. Lesnoe Khozyaistro 9:33-36 (in Russian).
  13. Brogowski, A., A.Czerwinski, and J. Pracz. 1977. [Ionic balance and the resistance of ornamental trees and shrubs to NaCl]. Roczniki. Nauk Roniczych A 102(2):51-64 (in Polish with English summary).
  14. Semoradova, E. and J. Materna. 1982. [Salt treatment of roads in winter: the response of trees and the content of chlorine in their assimilaton organs]. Scientia Agric. Bohemoslovaca 14(4):241-260.
  15. Sargent, C. S. 1888. The Ailanthus. Garden and Forest 1888: 1385-1386.
  16. Klincsek, P. 1976. [Investigations into the effect of cement dust in some frquent tree and shrub species]. Kertgaz dasag 8(3):71-76 (in Hungrian).
  17. Kozyukina, Ah.T. and V. I. Bolkov. 1973. [Salt resistance of species on the coast of the Sea of Azov]. Lesnoe Khozyaistro 9:33-36 (in Russian).
  18. Kim, M. H. 1975. [Studies on the effect of sulfer dixide gas on tree leaves]. Res. Rep. For. Res. Inst. Korea 22:31-36. (in Korean).
  19. Smith, W. H. 1972. Lead and mercury burden of urban woody plants. Science 176(4040):1237-1239.
  20. Davis, D. D., C. A. Miller, and J. B. Coppolino. 1978. Foliar response of eleven woody species to ozone with emphasis on black cherry. Proc. Am. Phytopath. Soc. [Abstract NE- 22] 4:185.
  21. Cozzo, D. 1972. [Initial behavior of Ailanthus altissima in experimental plantation]. Revista Forestal Argentina 16(2):47-52 (in Spanish). 21.0 21.1 21.2
  22. Magic, D. 1974. [Cultivated trees and forest weeds]. Acta Inst. Bot. Acad. Sci. Slov. (Czechoslovakia) 1A:33-38 (in Slovakian).
  23. Grime, J. P. 1965. Shade tolerance in flowering plants. Nature 208:161-163.
  24. Mergen, F. 1959. A toxic principle in the leaves of Ailanthus. Bot. Gazette 121:32-36. 24.0 24.1 24.2
  25. Feret, P. P. 1973. Early flowering in Ailanthus. Forest Sci. 19(3):237-9.
  26. Bory, G. And D. Clair-Maczulajtys. 1980. [Production, dissemination and ploymorphism of seeds in Ailanthus altissima]. Reuve Generale de Botanique 88(1049/1051):297-311 (in French)
  27. Rabe, E. P. and N. Bassuk. 1984. Adaptation of Ailanthus altissima to the urban environment through analysis of habitat usage and growth repsonse to soil compaction. Hortscience (Programs and Abstracts) 19(3):572.
  28. Adamik, K. J. 1955. The use of Ailanthus glandulosa as pulpwood. Tappi 38(9): 150A-153A.
  29. Watson, H. K. 1977. Present weed control projections for the year 2001. Unpublished manuscript. Copy on file at The Nature Conservancy, California Field Office, 785 Market Street, 3rd Floor, San Francisco, CA 94103. 29.0 29.1
  30. Fuller, T. C. and G. D. Barbe. 1985. The Bradley method of eliminating exotic plants from natural reserves. Fremontia 13:(2): 24-26. 30.0 30.1
  31. French, W. J. 1972. Cristulariella pyramidalis in Florida: an extension of range and new hosts. Plant Disease Report 56(2): 135-138.
  32. Misra, R. M. 1978. A mermithid parasite of Attera fabricella. Indian Forester 104(2):133-134.
  33. Weed Science Society of America. 1983. Herbicide handbook.
  34. Matthews, L. J. 1960. Weed identification and control: Broom. New Zealand J. Agriculture 100(3):229.
  35. Sterrett, J. P., J. A. Baden, III, and J. T. Davis. 1971. Defoliation of oak, maple and other woody plants with 2-chloro-ethyl phosphoric acid (68-240) and potassium iodide (KI). Abstracts Proc. NE Weed Sci. Soc., NY 25:376.
  36. Jones and Stokes Associates. 1984. Transmission right-of-way vegetation management program: analysis and recommendations. Prepared for Seattle City Light, Seattle, Washington. Copy on file at The Nature Conservancy, California Field Office, 785 Market Street, 3rd Floor, San Francisco, CA 94103.
  37. McHenry J. 1985. University of California, Davis, CA. Personal communication to Don Pitcher.
  38. Amechem Products, Inc. 1967. Tre-Hold: A tree paint for controlling regrowth of the sprout after trimming. Info Sheet Amechem Products #34. 2 pp.
  39. Thomas, T. Park Ranger, Santa Monica Mountains National Recreational Area. Personal communication. March 1985.

Additional References

  • Abrams, L. 1951. Illustrated flora of the Pacific states: Washington, Oregon, and

California. Vol. III. Geraniaceae to Scrophulariaceae. Stanford Univ. Press, Stanford, California. 866 pp.

  • Marshall, P. E. and G. R. Furnier. 1981. Growth responses of Ailanthus altissima

seedlings to SO2. Environ. Poll. Ser. A:149-153.

Original Document

Element Stewardship Abstract; M. Hoshovsky, 1988


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