Calotropis procera (Ait.) Ait. f. Family - Asclepiadaceae. Common Names(s) - Small crownflower. Giant milkweed. Synonym(s) - Asclepias procera Ait.

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

2

2.02

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

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

n

0

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

2

3.02

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

n=0

3.03

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

n=0

y

4

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

4.01

Produces spines, thorns or burrs

y=1, n=0

n

0

4.02

Allelopathic

y=1, n=0

n

0

4.03

Parasitic

y=1, n=0

n

0

4.04

Unpalatable to grazing animals

y=1, n=-1

n

-1

4.05

Toxic to animals

y=1, n=0

4.06

Host for recognized pests and pathogens

y=1, n=0

n

0

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

n

0

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

n

0

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

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

n

-1

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

1

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

y

1

7.04

Propagules adapted to wind dispersal

y=1, n=-1

y

1

7.05

Propagules water dispersed

y=1, n=-1

y

1

7.06

Propagules bird dispersed

y=1, n=-1

n

-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

7.08

Propagules survive passage through the gut

y=1, n=-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

y

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

n

1

Total score:

15

Notes

Source

1.01

(1)No evidence

(1)Staples, G.W. and D. R. Herbst. 2005. A Tropical Garden Flora. Planst Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI.

1.02

1.03

2.01

(1)C. procera is native to tropical Africa and Asia, West Africa as far south as Angola, North and East Africa, Madagascar, the Arabian Peninsula, Southern Asia, India and China to Malaysia.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

2.02

2.03

(1)C. procera is a plant of arid and semi-arid climates, and can tolerate very low annual rainfall (150 mm) and a dry season of up to 10 months. While normally found in dry habitats up to 1000 mm annual rainfall, it is also present in excessively drained soils in areas of higher precipitation. Mean annual monthly temperatures where C. procera is found are generally in the range 20-30°C. It is not frost tolerant.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

2.04

(1)now naturalized in Australia, many Pacific Islands, Mexico, Central and South America and the Caribbean islands. In these parts of the world it is considered as a noxious weed and harmful to natural biodiversity. (2)On Läna‘i it is sparingly naturalized along Keomuku Road, in sandy soil. Staples et al. (2000: 16) reported the species to be wind dispersed, and possibly also by vegetative means.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International. (2)Oppenheimer, H. 2008. New Hawaiian plant records for 2007. Pp. 22-38 in N.L. Evenhuis and L.G. Eldredge (eds.). Records of the Hawaii Biological Survey for 2007. Bishop Museum Occasional Papers 100: 1-55.

2.05

(1)C. procera has been widely introduced (Crothers and Newbound, 1998), mostly for fibre production, and is now naturalized in Australia, many Pacific Islands, Mexico, Central and South America and the Caribbean islands.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

3.01

(1)C. procera has been widely planted for fibre production and has become naturalized on the American and Australian continents. It is often abundant on degraded areas and is an indicator of overgrazing...C. procera was probably introduced into Australia as a garden plant or in the packing of camel saddles brought from India in the early 1900s (Crothers and Newbound, 1998). It became established in the Katherine area and spread along the Roper river in the 1950s. It is now a widespread weed in Northern Territory. It has also become naturalized in the semi-arid north of Queensland (Land Protection, 2001).

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

3.02

See 3.03 [a weed of disturbed agricultural areas reducing quality of grazing lands] (1)C. procera has been widely planted for fibre production and has become naturalized on the American and Australian continents. It is often abundant on degraded areas and is an indicator of overgrazing.C. procera is a widespread pioneer in semi-desert grassland and bushland (e.g. in Africa), and it also colonizes shifting sand-dunes such as in Rajasthan, India. However, due to its properties as a pioneer, there is a risk that this species may become a weed...C. procera favours open habitat with little competition (Francis, 2002), such as overgrazed pastures and rangelands. It is also found in coastal dunes, roadsides, watercourses and disturbed urban areas. It is often dominant in areas of abandoned cultivation, especially on sandy soils in areas of low rainfall. It can be used as an indicator of over-cultivation...now naturalized in Australia, many Pacific Islands, Mexico, Central and South America and the Caribbean islands. In these parts of the world it is considered as a noxious weed and harmful to natural biodiversity.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

3.03

(1)Calotropis procera is reported as a problem weed in pastures in Minas Gerais, Brazil. Its geographic distribution, phenology, popular names, propagation and uses are described. C. procera was originally introduced in the NE of the country some decades ago, but it has rapidly expanded towards the south of the country, and is now distributed in pastures in Sao Paulo, the N. of Paraná, Espirito Santo and Rio de Janeiro states. Although the weed is used as a medicinal plant and as a raw material for textiles in Africa, where it originated, its uses are yet unknown in Brazil. The weed does not only spread via wind dispersal, but it also floats in water and therefore spreads via irrigation and drainage channels. Chemical control of the weed is unknown. Manual control presents problems because of the high costs incurred and because the weed re-establishes itself with vigour when cut.

(1)Brandao M, 1995. Calotropis procera (Ait.) R. Br.: a problem pasture invader in Minas Gerais. Daphne, Revista do Herbário PAMG da EPAMIG, 5(1):68-71. (2)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International. (3)http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&ibra=all&card=S27 [Accessed 07 Aug 2008]

3.04

See 3.02 and 3.03

3.05

(1)Calatropis gigantea is listed as a weed, but no evidence of impacts have been documented.

(1)http://www.hear.org/gcw/species/calotropis_gigantea/ [Accessed 07 Aug 2008]

4.01

(1)A shrub or small tree, generally up to 2.5-4 m (max. 6) high. Stem round, usually simple (rarely branched), pale green, thickly covered with hoary pubescence which readily rubs off. Leaves decussate, obovate, acuminate 10-20 cm long and 4-10 cm wide. Inflorescence a dense, multiflowered, umbellate cyme arising from the nodes and appearing axillary or terminal. Corolla slightly campanulate, with 5 sepals that are 4-5 mm long; segments ovate, acute, rather concave, dull purple bordered with white on the upper side, silvery on the under side.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

4.02

(1)Abstract: Seed germination and seedling growth of two mulberry genotypes (Morus indica cv. MIHP and MIX) have been tested in order to find out any allelopathic effect of the phytochemicals present in the extracts of different plants used against mulberry diseases. Among the eight plant extracts tested, except the extracts of Datura alba, Adhatoda zeylanica and Oxalis corniculata (the last two to a less extent), none showed significant adverse effects on seed germination and seedling growth. Hence extracts of seven plants (leaves of Calotropis gigantia, Ocimum sanctum, Tagetes patula, bulb of Allium cepa and Rhizome of Zingiber officinales) can be used for controlling foliar disease in mulberry without causing any allelopathic effects.

(1) Kumar, P. M. Pratheesh; Vijayan, K. 1999. Effects of extracts of different plants on seed germination and seedling growth of mulberry (Morus indica L.). Journal of Plant Physiology 4(4): 343-345.

4.03

(1)No evidence

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

4.04

(1)Sheep, goats, and camels will eat the leaves of giant milkweed during droughts, but consumption is low. If the leaves are chopped and mixed with other feed, consumption greatly increases with no ill effects. (2)Cattle and goats have also been seen to extensively graze calotrope in the dry season (July to November), with no ill effects. (3)While no cases of stock poisoning have been recorded, this plant is regarded as unpalatable [contradicts first two references, but with no further information]

(1)http://www.fs.fed.us/global/iitf/pdf/shrubs/Calotropis%20procera.pdf [Accessed 07 Aug 2008] (2)Vitelli, J., B. Madigan, P. Wilkinson and P. van Haaren. Chemical control options for calotrope. Available from http://www.publish.csiro.au/media/client/RJ07064preprint.pdf [Accessed 07 Aug 2008] (3)http://www.savanna.org.au/km/kb_weeds.html [Accessed 08 Aug 2008]

4.05

Possibly toxic, but see 4.04 (1)It is reported to contain a bitter principle called calotropin which is a cardiac poison. In western Africa, the plant has been suspected of causing ill-effects and sometimes death in sheep and goats (2)Like its larger relatives, C. procera is toxic in all its parts. (3)While no cases of stock poisoning have been recorded, this plant is regarded as unpalatable.

(1)El-Badwi SMA, Adam SEI, et al., 1998. Studies on laticiferous plants: Toxic effects in goats on Calotropis procera latex given by different routes of administration. DTW Deutsche Tieraerztliche Wochenschrift, 105(11):425-427. (2)Staples, G.W. and D. R. Herbst. 2005. A Tropical Garden Flora. Planst Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI. (3)http://www.savanna.org.au/km/kb_weeds.html [Accessed 08 Aug 2008]

4.06

for already widespread pests (1)In Australia, no natural enemies of this weed are known. Colletotrichum dematium, Danaus chrysippus and Aphis nerii have been reported attacking C. procera (Little et al., 1974; Tahir and Jamaluddin, 1993; Kapoor and Gautam, 1994; Shukla and Bhatnagar, 1995; Samraoui, 1996; Barreto et al., 1999). Dacus longistylus has been reported to assist in the natural control of C. procera in Sudan (Venkatraman and El-Khidir, 1967).
Pests recorded
Insects:
Aonidiella orientalis (oriental yellow scale)
Aphis nerii (sweet pepper aphid)
Brachyunguis calotropicus
Dacus longistylus
Danaus chrysippus
Diaprepes famelicus (root borer, sugarcane)
Poekilocerus pictus (grasshopper,painted)
Spilostethus pandurus militaris
Fungus diseases:
Colletotrichum dematium (leaf spot)
Colletotrichum demiatum
Bacterial diseases:
Rhizobium radiobacter (crown gall)
Rhizobium rhizogenes (gall)
Pests recorded at the generic level (Calotropis):
Insects:
Pseudaulacaspis pentagona (mulberry scale)
Pests recorded at the family level (Asclepiadaceae):
Insects:
Danaus chrysippus

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

4.07

(1)Like its larger relatives, C. procera is toxic in all its parts. (2)The latex is poisonous, containing digitalis-like compounds that affect the heart, and is used to make arrow poison. (3)The latex is toxic and can cause blisters and rash in sensitive persons. (4)Its milky sap can cause blistering and irritation in humans.

(1)Staples, G.W. and D. R. Herbst. 2005. A Tropical Garden Flora. Planst Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI. (2)http://www.herbsociety.org/promplant/cprocera.php [Accessed 07 Aug 2008] (3)http://www.fs.fed.us/global/iitf/pdf/shrubs/Calotropis%20procera.pdf [Accessed 07 Aug 2008] (4)http://www.savanna.org.au/km/kb_weeds.html [Accessed 08 Aug 2008]

4.08

(1)Well-studied species not documented to increase fire hazard or risk (2)The lack of fuel under dense calotrope stands prevents the establishment of hot fires that are required for effective control.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International. (2)Vitelli, J., B. Madigan, P. Wilkinson and P. van Haaren. Chemical control options for calotrope. Available from http://www.publish.csiro.au/media/client/RJ07064preprint.pdf [Accessed 07 Aug 2008]

4.09

(1)Giant milkweed favors open habitat with little competition...Competition with tall weeds, brush, and especially grass weakens existing plants, and being overtopped and shaded by trees soon eliminates them.

(1)http://www.fs.fed.us/global/iitf/pdf/shrubs/Calotropis%20procera.pdf [Accessed 07 Aug 2008]

4.10

(1)It will grow on a wide variety of soil types and will survive on alkaline and saline soils though prefers free-draining sandy soils. It is deep-rooted, and so rarely grows in shallow soils over unfractured rock. Soils of all textures and derived from most parent materials are tolerated.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

4.11

(1)A shrub or small tree, generally up to 2.5-4 m (max. 6) high.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

4.12

(1) It successfully competes with desirable pasture species and is capable of forming dense thickets that interfere with stock management, particularly mustering activities. (2)Giant milkweed does not form dense stands, normally occurring as scattered individuals [contradicts first reference] (3)The plant forms dense thickets, particularly on alluvial flats along rivers.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International. (2)http://www.fs.fed.us/global/iitf/pdf/shrubs/Calotropis%20procera.pdf [Accessed 07 Aug 2008] (3)Vitelli, J., B. Madigan, P. Wilkinson and P. van Haaren. Chemical control options for calotrope. Available from http://www.publish.csiro.au/media/client/RJ07064preprint.pdf [Accessed 07 Aug 2008]

5.01

Terrestrial

5.02

Asclepiadaceae

5.03

Asclepiadaceae

5.04

(1)A shrub or small tree, generally up to 2.5-4 m (max. 6) high. Stem round, usually simple (rarely branched), pale green, thickly covered with hoary pubescence which readily rubs off. Leaves decussate, obovate, acuminate 10-20 cm long and 4-10 cm wide. Inflorescence a dense, multiflowered, umbellate cyme arising from the nodes and appearing axillary or terminal. Corolla slightly campanulate, with 5 sepals that are 4-5 mm long; segments ovate, acute, rather concave, dull purple bordered with white on the upper side, silvery on the under side.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

6.01

(1)No evidence

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

6.02

(1)unlike its larger relative, though, it readily sets fruit, and the seeds are easily dispersed by their silky parachutes.

(1)Staples, G.W. and D. R. Herbst. 2005. A Tropical Garden Flora. Planst Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI.

6.03

No information found on hybridization

6.04

(1)The chromosome number is x=11 (2n=22). Progeny are genetically divergent and different from the parents. They are highly cross-pollinated through insects such as monarch butterflies. The very broad native range suggests high genetic diversity though this has not been assessed in terms of product quality or other characteristics.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

6.05

(1)Studies at 3 sites in the Karachi area, Pakistan, showed that the main pollinators of C. procera subsp. hamiltonii were males and females of Xylocopa pubescens and females of X. fenestrata; workers of Apis florea were minor pollinators. The levels of pollinator activity differed significantly between the sites studied. Pollinaria removal and pollinia insertion mechanisms are described. The pollen/ovule ratio was low (6.14).

(1)Ali T, Ali SI, 1989. Pollination biology of Calotropis procera subsp. hamiltonii (Asclepiadaceae). Phyton (Horn), 29(2):175-188.

6.06

(1)Dispersal: Mainly spread by seed that is transported by wind and water but also locally by suckering from the roots. (2)In established plants the wet season also promotes new growth, including suckering from roots…Infestations increase in size and density both by suckering from roots and crown and by seedlings germinating from seeds dropped near the parent plants (3)Vegetative propagation through half stumps assumes a special importance as compared with the entire stumps because they help in faster multiplication of the parent genotype with plus characters, as each plant gives rise to 2 half stumps. Stumps also help in propagating only 1 plant. Vegetative propagation through stem and root cuttings is very useful in large-scale multiplication of the superior genotypes.

(1)http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&ibra=all&card=S27 [Accessed 07 Aug 2008] (2)Parsons, W. T., and Cuthbertson, E. G. .2001. 'Noxious Weeds of Australia.' CSIRO Publishing. Melbourne. (3)http://www.worldagroforestry.org/Sea/Products/AFDbases/AF/asp/SpeciesInfo.asp?SpID=421 [Accessed 07 Aug 2008]

6.07

(1)It appears that the age at first flowering is at least two years, with flowers emerging in winter

(1)Parsons, W. T., and Cuthbertson, E. G. .2001. 'Noxious Weeds of Australia.' CSIRO Publishing. Melbourne.

7.01

No indication that plants are dispersed by people or vehicles in heavily trafficked areas (1)The weed does not only spread via wind dispersal, but it also floats in water and therefore spreads via irrigation and drainage channels. (2)Dispersal: Mainly spread by seed that is transported by wind and water but also locally by suckering from the roots.

(1)Brandao M, 1995. Calotropis procera (Ait.) R. Br.: a problem pasture invader in Minas Gerais. Daphne, Revista do Herbário PAMG da EPAMIG, 5(1):68-71. (2)http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&ibra=all&card=S27 [Accessed 07 Aug 2008]

7.02

(1)C. procera has been widely planted for fibre production and has become naturalized on the American and Australian continents.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

7.03

(1)Weed seeds typical to the Top end that may be in your hay: Rubber bush Calotropis procera Mimosa Bush Acacia farnesiana Hyptis Hyptis suaveolens Parkinsonia Parkinsonia aculeata Noogoora Burr Xanthium strumarium Bellyache Bush Jatropha gossypifolia Castor Oil Plant Ricinus communis Coffee Senna Senna occidentalis Devil’s Claw Martynia annua [wind-dispersed seeds of C. procera can easily spread into & invade agricultural fields and contaminate crops]

(1)Land Talk. 2004. Newsletter of the `Centralian Land Management Association’ (CLMA) 12(1): 1-6. Available from http://www.clma.com.au/Landtalk%20PDF%20for%20website/LandTalk%20February%2004.pdf [Accessed 08 Aug 2008]

7.04

(1)it readily sets fruit, and the seeds are easily dispersed by their silky parachutes.

(1)Staples, G.W. and D. R. Herbst. 2005. A Tropical Garden Flora. Planst Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI.

7.05

(1)The weed does not only spread via wind dispersal, but it also floats in water and therefore spreads via irrigation and drainage channels. (2)Dispersal: Mainly spread by seed that is transported by wind and water but also locally by suckering from the roots.

(1)Brandao M, 1995. Calotropis procera (Ait.) R. Br.: a problem pasture invader in Minas Gerais. Daphne, Revista do Herbário PAMG da EPAMIG, 5(1):68-71. (2)http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&ibra=all&card=S27 [Accessed 07 Aug 2008]

7.06

Not fleshy-fruited or adapted for bird dispersal

7.07

(1)Seeds are dispersed by wind and by animals. [possibly adheres to fur but no further references corroborate this]

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

7.08

No information found on gut passage

8.01

(1)Flowering and fruiting take place throughout the year (Little et al., 1974). Hundreds to thousand of seeds may be produced per plant every year. The average seed weight is approximately 0.01 g/per seed or 100,000 seeds/kg. (Francis, 2002). The seeds achieved 89% germination within 7-64 days after sowing in a potting mix.

(1)CAB International, 2005. Forestry Compendium. Wallingford, UK: CAB International.

8.02

(1)The significance of seed dormancy for wild species is so well known that it needs no further emphasis. A dormancy level of 35-50% in the C-type population compared with 2-12% for A- and B-types explains in part the success of the former population in natural conditions. (2)Storage Behaviour: Orthodox Storage Conditions: Long-term storage under IPGRI preferred conditions at RBG Kew, WP. Oldest collection 22 years; germination change 100 to 90%, 13 years, 1 collection

(1)Amritphale, D., Jagdish C. Gupta and Shamanta Iyengar. 1984. Germination Polymorphism in Sympatric Populations of Calotropis Procera. Oikos 42, No. 2, (Jan., 1984), pp. 220-224 (2)http://data.kew.org/sid/SidServlet?ID=4274&Num=Ba2 [Accessed 08 Aug 2008]

8.03

(1)Abstract. Calotrope (Calotropis procera (Aiton) W.T.Aiton), an exotic shrub or small tree species, is currently invading the tropical savannahs of northern Australia. A chemical trial involving 11 herbicides and 4 application methods (foliar, basal bark, cut stump and soil applied) was undertaken to identify effective chemicals to control calotrope. Of the foliar herbicides tested, imazapyr provided 100% mortality at the rates applied, and the higher rate of metsulfuron-methyl killed 100% of the treated plants. The herbicides 2,4-D butyl ester, fluroxypyr, triclopyr and triclopyr/picloram killed greater than 80% of the plants when applied by a basal bark or cut stump (when cut 5 cm above ground level) method of application. Plants cut close to ground level (5 cm) were controlled more effectively than plants cut 20 cm above ground level. Chemical control (foliar and cut stump spraying) is a cost effective tool to treat calotrope densities <800 plants/ha. Adoption of pasture management practices that promote perennial grasses, in conjunction with strategic chemical control, would further increase the effectiveness and reduce the costs of controlling vast areas of this weed.

(1)Vitelli, J., B. Madigan, P. Wilkinson and P. van Haaren. Chemical control options for calotrope. Available from http://www.publish.csiro.au/media/client/RJ07064preprint.pdf [Accessed 07 Aug 2008]

8.04

(1)Manual control presents problems because of the high costs incurred and because the weed re-establishes itself with vigour when cut. (2)It can spread rapidly from the base of plants, and can regrow from the root system in favourable conditions even if the aboveground plant has disappeared (3)Using the reserves in its large taproot, giant milkweed can resprout year after year when burned or cut.

(1)Brandao M, 1995. Calotropis procera (Ait.) R. Br.: a problem pasture invader in Minas Gerais. Daphne, Revista do Herbário PAMG da EPAMIG, 5(1):68-71. (2)Land Protection, 2001. Calotropis procera. NRM Facts PP41. Australia: Queensland Government (Department of Natural Resources and Mines). (3)http://www.fs.fed.us/global/iitf/pdf/shrubs/Calotropis%20procera.pdf [Accessed 07 Aug 2008]

8.05

Apparently few pests of Calotropis in Hawaiian Islands, and none appear to have adverse effects (1)Pests are few, though heavy infestations of the gaudy black-and-white caterpillars of the monarch butterfly may defoliate the plant. The caterpillars do not do permanent harm to the plant and are best left alone [description from C. gigantea may also apply to C. procera]

(1)Staples, G.W. and D. R. Herbst. 2005. A Tropical Garden Flora. Planst Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI.