Ambrosia psilostachya DC. Family - Asteraceae. Common Names(s) - Cuman ragweed, perennial ragweed, western ragweed. Synonym(s) - Ambrosia californica Rydb.

Answer

Score

1.01

Is the species highly domesticated?

y=-3, n=0

n

0

1.02

Has the species become naturalized where grown?

y=1, n=-1

1.03

Does the species have weedy races?

y=-1, n=-1

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

0

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

1

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

y

1

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

1

2.05

Does the species have a history of repeated introductions outside its natural range?

y=-2, ?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

1

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

y

1

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

y

2

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

n

0

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

1

4.01

Produces spines, thorns or burrs

y=1, n=0

n

0

4.02

Allelopathic

y=1, n=0

y

1

4.03

Parasitic

y=1, n=0

n

0

4.04

Unpalatable to grazing animals

y=1, n=-1

4.05

Toxic to animals

y=1, n=0

n

0

4.06

Host for recognized pests and pathogens

y=1, n=0

y

1

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

y

1

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

y

1

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

n

0

4.10

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

y

1

4.11

Climbing or smothering growth habit

y=1, n=0

n

0

4.12

Forms dense thickets

y=1, n=0

y

1

5.01

Aquatic

y=5, n=0

n

0

5.02

Grass

y=1, n=0

n

0

5.03

Nitrogen fixing woody plant

y=1, n=0

n

0

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

y

1

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

0

6.02

Produces viable seed.

y=1, n=-1

y

1

6.03

Hybridizes naturally

y=1, n=-1

6.04

Self-compatible or apomictic

y=1, n=-1

6.05

Requires specialist pollinators

y=-1, n=0

n

0

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

y

1

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

2

0

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

y

1

7.02

Propagules dispersed intentionally by people

y=1, n=-1

n

-1

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

y

1

7.02

Propagules adapted to wind dispersal

y=1, n=-1

n

-1

7.05

Propagules water dispersed

y=1, n=-1

n

-1

7.06

Propagules bird dispersed

y=1, n=-1

n

-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

y

1

7.08

Propagules survive passage through the gut

y=1, n=-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

n

-1

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

y

1

8.03

Well controlled by herbicides

y=-1, n=1

y

-1

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

y

1

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

Total score:

15

Notes

Source

1.01

(1)No evidence

(1)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

1.02

1.03

2.01

(1)Western ragweed's range extends from southern British Columbia east to Nova Scotia [51,81,107] and southward through the United States from the Appalachians to the West Coast and into central Mexico [38,74,90,104,108]...Climate ranges from continental to coastal with short, warm to hot summers and long, cold winters [1,3,16,129]. Often, there are moderately strong surface winds [1]. Humidity is semiarid to moist subhumid [42,44,86]. Annual precipitation ranges from 5 to 34 inches (114-880 mm) with 60 to 80 percent occurring during the growing season [19,23,39,56,75,114,125]. Temperatures vary from an average 72 degrees Fahrenheit (22 deg C) in July to a January average of 11 degrees Fahrenheit (-11.5 deg C) [124].

(1)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

2.02

(1)Western ragweed's range extends from southern British Columbia east to Nova Scotia [51,81,107] and southward through the United States from the Appalachians to the West Coast and into central Mexico [38,74,90,104,108]...Climate ranges from continental to coastal with short, warm to hot summers and long, cold winters [1,3,16,129]. Often, there are moderately strong surface winds [1]. Humidity is semiarid to moist subhumid [42,44,86]. Annual precipitation ranges from 5 to 34 inches (114-880 mm) with 60 to 80 percent occurring during the growing season [19,23,39,56,75,114,125]. Temperatures vary from an average 72 degrees Fahrenheit (22 deg C) in July to a January average of 11 degrees Fahrenheit (-11.5 deg C) [native range suitable for higher elevations of Hawaiian Islands, but unclear if plant would survive at lower elevation, more tropical climates]

(1)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

2.03

(1)Climate ranges from continental to coastal with short, warm to hot summers and long, cold winters [1,3,16,129]. Often, there are moderately strong surface winds [1]. Humidity is semiarid to moist subhumid [42,44,86]. Annual precipitation ranges from 5 to 34 inches (114-880 mm) with 60 to 80 percent occurring during the growing season [19,23,39,56,75,114,125]. Temperatures vary from an average 72 degrees Fahrenheit (22 deg C) in July to a January average of 11 degrees Fahrenheit (-11.5 deg C) [124]. Western ragweed grows at elevations ranging from 850 to 7,400 feet (259-2,256 m)

(1)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

2.04

(1)This paper describes Ambrosia psilostachya DC. (Asteraceae) as a plant newly recorded to Taiwan. It has established its feral population in Kaohsiung County, and is closely related to exotic A. artemisiaefolia L. of Taiwan. However, the two species are distinguishable by the structure of their pinnatifid leaves. This paper also provides its distribution, living habitat, breeding (flowering and fruiting) period.

(1)Yen-Hsueh Tseng and Ching-I Peng. 2004. Ambrosia psilostachya DC. (Asteraceae) a Newly Naturalized Plant in Taiwan. Unique biological research 6 (1) ︰ 71-74.

2.05

(1)Western ragweed's range extends from southern British Columbia east to Nova Scotia [51,81,107] and southward through the United States from the Appalachians to the West Coast and into central Mexico [38,74,90,104,108]. Western ragweed was introduced from North America into Europe and southwestern Russia [115]. (2)The plant originates in North America. The general distribution includes North America (Canada, the USA, and Mexico), Europe (Belgium, Hungary, Germany, Denmark, Poland, Holland, Spain, France, and Sweden), and Australia. On the territory of the former USSR it is now distributed in the European part of the Russian Federation and in Central Asia (Kazakhstan). In the Russian Federation the centers of weed are located in 5 areas, i.e., Volgograd (60 hectares), Orenburg (114 hectares) and Samara (153 hectares) Regions, Stavropol Territory (210 hectares) and Bashkortostan (622 hectares).

(1)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009] (2)http://www.agroatlas.ru/en/content/weeds/Ambrosia_psilostachya/ [Accessed 02 Mar 2009]

3.01

(1)has become a serious weed in parts of eastern Europe and western Asia. It also occurs in South America, Japan, Mauritius and Australia.

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

3.02

(1)usually found as a weed along roadsides, in uncultivated fields, vacant lots and waste places. (2)Western ragweed is a major invader of deteriorating rangeland. It readily moves into open habitat in prairies

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia. (2)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

3.03

(1)Perennial ragweed is a strongly competitive plant, often growing densely to the detriment of crop and pasture...It is not palatable to stock, dense infestations thus reducing pasture productivity considerably. (2)Notes: Forms dense colonies. A weed of crops and pasture. (3)Perennial Ragweed is one of the most difficultly eradicable weeds, being included in lists of quarantine weeds in many countries. Weed is nocuous. It causes reduced productivity of cultures; quality of crop (and forages) also decreases, and efficiency of pastures weakens.

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia. (2)http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&state=&s=&region=&form=herb&fc=green&card=H44 [Accessed 02 Mar 2009] (3)http://www.agroatlas.ru/en/content/weeds/Ambrosia_psilostachya/ [Accessed 02 Mar 2009]

3.04

(1)usually found as a weed along roadsides, in uncultivated fields, vacant lots and waste places. [mostly a disturbance weed with negative impacts to agriculture] (2)Western ragweed is a major invader of deteriorating rangeland. It readily moves into open habitat in prairies

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia. (2)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

3.05

(1)A. artemisiifolia is a quarantine weed, litters practically all field crops; it is especially harmful in vegetable and tilled crops. Having powerful root system, the weed strongly dries up and impoverishes soil. Animals eating Ambrosia produce milk and dairy products with unpleasant smack and smell. Pollen is dangerous to human health, causing sharp forms of pollinosis (autumn hay fever). Control measures include quarantine actions, i.e., prevention of Ambrosia import with grain from quarantine zones to areas free of the weed, regular inspection of agricultural lands, full cleaning of sowing material; land treatment, i.e., stubble shelling with subsequent plowing and surface soil treatment, on tilling crops - pre-emergence harrowing before formation of two pairs of Ambrosia true leaves, and repeated interrow treatments during a vegetative period, repeated mowing before fructification of the weed on nearby sites, correct alternation of cultures in a crop rotation, manual weeding, black fallow; chemical method (herbicides); biological method (Lygogramma suturalis, Tarachidia candefacta, planting perennial cereal grasses for two-three years, treatments with the biological products containing pathogens causing Ambrosia diseases, for example, White Rust.

(1)http://www.agroatlas.ru/en/content/weeds/Ambrosia_artemisiifolia/ [Accessed 02 Mar 2009]

4.01

(1)Western ragweed grows nearly four feet tall in some places, but most North Dakota plants are about half that height. Plants are perennial from creeping rootstalks and thus form clumps of many stems. Leaves are about 2-3 inches long, opposite, and deeply cut into narrow lobes that are again lobed. About 5-10 tiny yellow flowers form heads about one eighth inch across; these are in turn grouped into spikes about 1-2 inches long that arise from the upper half of the plant and overtop the leaves. [no evidence]

(1)http://www.npwrc.usgs.gov/resource/plants/wildflwr/species/ambrpsil.htm [Accessed 02 Mar 2009]

4.02

(1)Extracts from aerial growth are allelopathic, inhibiting germination and early seedling growth of several plant species. (2)Western ragweed root exudate significantly inhibited the formation of nodules on legume roots, which decreases their ability to fix nitrogen

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia. (2)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

4.03

(1)No evidence

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

4.04

(1)It is not palatable to stock, dense infestations thus reducing pasture productivity considerably. (2)Managers rate the forage value of western ragweed as fair [121]. The foliage and stems contain cinnamic acid and sesquiterpene lactones that deter herbivory [129]. However, western ragweed is not considered a poisonous plant [88]. It is moderately important as ungulate forage [24,31,48,98,103]...Ragweeds are normally considered to be unpalatable but when treated with 2,4-D become palatable. Treated plants may, however, accumulate nitrates to a toxic level [76]. In Montana, Utah, and Wyoming, western ragweed palatability is poor for ungulates and waterfowl. (3)Young foliage of western ragweed is eaten by livestock and whitetail deer. [plant may be palatable at certain stages of life cycle]

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia. (2)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009] (3)http://www.honeycreekfriends.com/plantofweek/ragweed.html [Accessed 03 Mar 2009]

4.05

(1)The foliage and stems contain cinnamic acid and sesquiterpene lactones that deter herbivory [129]. However, western ragweed is not considered a poisonous plant [88].

(1)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

4.06

(1)INTRODUCTION Pierce’s disease (PD), caused by the bacterial pathogen Xylella fastidiosa, is the greatest limiting factor for growing Vitis vinifera in most of Texas. Associations of X. fastidiosa, known vector glassy wing sharpshooter Homalodisca coagulata, other xylophagous insects, and numerous host plant species in warmer climates of Texas are apparently ancient and complex. Widespread death of European grape plants has been a common occurrence in much of Texas, perhaps since the first of many plant introductions 400 years ago. There are numerous scientific advantages to studying a biological system where pathogen, vectors, and host plants are native and endemic. However, little is known about the diversity of plants and the bacterium, or potential biocontrol agents in warmer regions of Texas...Table 3. Five weed species in Asteraceae collected near four vineyards and positive for Xylella fastidiosa with serology and dilution plating in summer and fall 2003.

(1)http://pd.pipra.org/Proceedings/2004/2004_178-181.pdf [Accessed 02 Mar 2009]

4.07

(1)The outstanding feature of perennial ragweed, however, is the allergic inflammation of the nose suffered by many people because of its pollen. The illness is so debilitating that some areas of the United States, Oregon for example, have instituted eradication programmes on ragweed so that they can advertise as being 'ragweed free' to attract tourists.

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

4.08

(1)Perennial ragweed is a strongly competitive plant, often growing densely to the detriment of crop and pasture. [dense cover and fire adaptation would likely increase fire hazard] (2)As a component of North American grasslands, western ragweed has evolved with fire. Soil can insulate roots from lethal temperatures during a fire. Surface rhizomes of western ragweed may be killed during a fire; however, the plant also has deep-seated rhizomes which would survive most fires

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia. (2)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

4.09

(1)Light Requirement: Sun , Part Shade (2)Sun Exposure: Full Sun (3)Cultivation: The preference is full sun, dry conditions, and poor soil.

(1)http://www.wildflower.org/plants/result.php?id_plant=AMPS [Accessed 02 Mar 2009] (2)http://zipcodezoo.com/Plants/A/Ambrosia_psilostachya/ [Accessed 02 Mar 2009] (3)http://www.illinoiswildflowers.info/prairie/plantx/ws_ragweedx.htm [Accessed 02 Mar 2009]

4.10

(1)Western ragweed grows at elevations ranging from 850 to 7,400 feet (259-2,256 m) and in many types of soils [18,30,60,66,69]. Soil textures are predominantly loams, varying from silty clay loams to fine sandy loams [23,61,122]. Soil pH ranges from 5.7 to 7.9 [22,105]. Soils often have little organic matter and are low in fertility [34].

(1)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

4.11

(1)Western ragweed is a warm-season, native perennial forb. The main stem rises from shallow (2 inches [5 cm]) or deep, branching rhizomes which extend down 3 to 6 feet (0.9-1.8 m) [6,70]. Stems are slender and branched, usually 1 to 2 feet (30-60 cm) tall [59,70]. Plants are monoecious with unisexual flowers; male flowers occur at the top of the plant and female flowers are axillary [41]. Achenes have a short beak and small blunt tubercles on top [41].

(1)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

4.12

(1)Perennial ragweed is a strongly competitive plant, often growing densely to the detriment of crop and pasture.

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

5.01

(1)Terrestrial

(1)DiTomaso, J. and E. A. Healy. 2007. Weeds of California and Other Western States. ANR Publications. Oakland, CA.

5.02

(1)Asteraceae

(1)DiTomaso, J. and E. A. Healy. 2007. Weeds of California and Other Western States. ANR Publications. Oakland, CA.

5.03

(1)Asteraceae

(1)DiTomaso, J. and E. A. Healy. 2007. Weeds of California and Other Western States. ANR Publications. Oakland, CA.

5.04

(1)RAUNKIAER LIFE FORM : Geophyte

(1)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

6.01

(1)No evidence

(1)DiTomaso, J. and E. A. Healy. 2007. Weeds of California and Other Western States. ANR Publications. Oakland, CA.

6.02

(1)reproducing by seed and vegetatively from a strong rootstock and creeping roots.

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

6.03

(1)"Hybrids between Ambrosia psilostachya and A. artemisiifolia have been called A. ×intergradiens W. H. Wagner." [Unknown if hybrids are natural]

(1)http://biology.burke.washington.edu/herbarium/waflora/checklist.php?Family=Asteraceae&view=list [Accessed 02 Mar 2009]

6.04

(1)Observations of pollen-tube growth and seed set following controlled pollinations demonstrated that plants of A. artemisiifolia possess a strong self-incompatibility mechanism, contrary to earlier reports and assumptions. [related species self-incompatible]

(1)Friedman, J. and S. C. H. Barrett. 2008. High Outcrossing in the Annual Colonizing Species Ambrosia artemisiifolia (Asteraceae). Annals of Botany 101: 1303–1309.

6.05

(1)They are wind-pollinated, the pollen of all species being highly allergenic.

(1)Wagner, W. L., D. R. Herbs and S. H. Sohmer. 1999. Manual of Flowering Plants of Hawaii. University of Hawaii and Bishop Museum Press. Honolulu, HI.

6.06

(1)Unlike annual bursage and giant ragweed, western ragweed can reproduce vegetatively from creeping roots (2)Local spread and an increase in density occurs with the production of shoots from buds along the creeping roots.

(1)DiTomaso, J. and E. A. Healy. 2007. Weeds of California and Other Western States. ANR Publications. Oakland, CA. (2)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

6.07

(1)During the first growing season, seedlings will not flower or produce additional shoots. However, in the second year, additional shoots will develop from rhizomes and form a colony.

(1)http://www.honeycreekfriends.com/plantofweek/ragweed.html [Accessed 03 Mar 2009]

7.01

(1)Spread also occurs when the seeds, in mud, stick to animals, farm machinery and vehicles of all kinds. It is also commonly spread when contaminated soil and gravel are moved during road grading and roadmaking, and when such soil is used as garden topdressing.

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

7.02

(1)Spread also occurs when the seeds, in mud, stick to animals, farm machinery and vehicles of all kinds. It is also commonly spread when contaminated soil and gravel are moved during road grading and roadmaking, and when such soil is used as garden topdressing.

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

7.03

(1)brown achene-like fruits obovoid, hairy, short-pointed, with fewer tubercles than the preceding species or sometimes none at all; they are often found in grass and clover seed and in baled hay.

(1)Georgia, A. E. 1919. A Manual of Weeds: With Descriptions of All the Most Pernicious and Troublesome Plants in the United States and Canada, Their Habits of Growth and Distribution, with Methods of Control. The MacMillian Company. New York.

7.02

(1)Dispersal: Spread by seed attached to animals or in mud, and by creeping roots.

(1)http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&state=&s=&region=&form=herb&fc=green&card=H44 [Accessed 02 Mar 2009]

7.05

(1)Dispersal: Spread by seed attached to animals or in mud, and by creeping roots. [no evidence]

(1)http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&state=&s=&region=&form=herb&fc=green&card=H44 [Accessed 02 Mar 2009]

7.06

(1)Dispersal: Spread by seed attached to animals or in mud, and by creeping roots. [no evidence]

(1)http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&state=&s=&region=&form=herb&fc=green&card=H44 [Accessed 02 Mar 2009]

7.07

(1)Perennial ragweed spreads widely because the fruit is well adapted to tangle in wool and stick to furred animals, clothing, bags and other fibrous materials.

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

7.08

(1) Like Ambrosia artemesiifolia (Common Ragweed), the seeds of Western Ragweed are popular with many kinds of songbirds and upland gamebirds (see Bird Table). The seeds are nutritious and remain available through the winter months. Some rodents eat the seeds, including the Thirteen-Lined Ground Squirrel and Prairie Vole. Mammalian herbivores eat the bitter foliage of this and other ragweeds only to a limited extent. It is possible that the seeds are only semi-digestible, and may be distributed to some extent by these animals.

(1)http://www.illinoiswildflowers.info/prairie/plantx/ws_ragweedx.htm [Accessed 02 Mar 2009]

8.01

(1)Seed production is of secondary importance for western ragweed since it is a perennial and produces new growth from rootstocks. During the first growing season, seedlings will not flower or produce additional shoots. However, in the second year, additional shoots will develop from rhizomes and form a colony.

(1)http://www.honeycreekfriends.com/plantofweek/ragweed.html [Accessed 03 Mar 2009]

8.02

(1)…dormant seeds are able to survive many years in the soil, as is demonstrated by the reappearance of a patch of perennial ragweed at Speed, Victoria, several years after all existing plants had been eliminated.

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia.

8.03

(1)Effective control can, however, be obtained with herbicides. Such treatments may need to be repeated regularly over a period of several years to prevent recolonization from dormant seeds in the soil. Spray annually at the budding stage with low volatile ester 2,4-D, triclopyr, dicamba or picloram + 2,4-D. (2)Chemical Control: Herbicide should be applied to western ragweed during the late vegetative stage before the formation of flowerbuds; western ragweed is moderately or totally resistant during other growth phases [93,111]. Before flowering, it is susceptible and may be controlled with one foliage spray application at 1 pound active ingredient per acre(1.1 kg ai/ha) for 2,4-D, 2,4,5-T, Silvex, 2,4,-D-B or 0.25 pound active ingredient per acre (0.28 kg ai/a) Grazon PC and Banvel [43,83,93].Grazon P + D will give control for more than 1 year [43].

(1)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia. (2)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Mar 2009]

8.04

(1)This is a much harder weed to combat than its annual relatives, for one must have a care in cultivation not to break up and spread abroad the creeping rootstocks and thus increase the plague. (2)Cultivation is not an effective means of control because of the difficulty of killing the extensive root system. It is, in fact, advantageous to the plant because it spreads root fragments and stimulates new growth. (3)a component of North American grasslands, western ragweed has evolved with fire. Soil can insulate roots from lethal temperatures during a fire. Surface rhizomes of western ragweed may be killed during a fire; however, the plant also has deep-seated rhizomes which would survive most fires [6].

(1)Georgia, A. E. 1919. A Manual of Weeds: With Descriptions of All the Most Pernicious and Troublesome Plants in the United States and Canada, Their Habits of Growth and Distribution, with Methods of Control. The MacMillian Company. New York. (2)Parsons, W. T. and E. G. Cuthbertson . 2001. Noxious Weeds of Australia. CSIRO Publishing. Collingwood, Australia. (3)http://www.fs.fed.us/database/feis/plants/forb/ambpsi/all.html [Accessed 02 Marh 2009]

8.05

Unknown