Large Seeded Dodder (Cuscuta indecora)

Present distribution

Scientific name:	Cuscuta indecora Choisy
Common name(s):	Large seeded dodder

This weed is not known to be naturalised in Victoria

Habitat:

Parasitic weed of woody and herbaceous plants (Lundell, ‘43); including economically important agricultural crops (i.e. alfalfa, asparagus, clovers, cucurbits, onions (UC, ’76), flax, linseed, and lucerne (Parker and Riches, ’93). Invades moist fields, roadsides (Hickman, ’93), floodplains (Ohio DNR).

Potential distribution

Potential distribution produced from CLIMATE modelling refined by applying suitable landuse and vegetation type overlays with CMA boundaries

Map Overlays Used

Land Use:
Broadacre cropping, horticulture, pasture dryland, and pasture irrigation.

Broad vegetation types
Coastal scrubs and grassland; coastal grassy woodland; inland slopes woodland; sedge-ridge woodland; grassland; plains grassy woodland; valley grassy forest; herb-rich woodland; sub-alpine grassy woodland; montane grassy woodland; riverine grassy woodland; mallee woodland; and Wimmera/Mallee woodland.

Colours indicate possibility of Cuscuta indecora infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.

map showing the potential distibution of large seeded dodder

Red= Very high	Orange = Medium
Yellow = High	Green = Likely

Impact

QUESTION	COMMENTS	RATING	CONFIDENCE
Social
1. Restrict human access?	Negligible impact. As the parasite mimics the growth form of its host, the impact of its presence on human access is not altered from that of the host only.	L	ML
2. Reduce tourism?	Weeds not obvious to the ‘average’ visitor. Parasite is not likely to be distinguished separately to its host.	L	L
3. Injurious to people?	No effect, no prickles, no injuries recorded in literature reviewed.	L	L
4. Damage to cultural sites?	Little, or negligible, effect on aesthetics, or structure of site. As the parasite mimics the growth form of its host, the impact of its presence on site structure is not altered from that of the host only.	L	L
Abiotic
5. Impact flow?	Little effect on water flow. Terrestrial species.	L	M
6. Impact water quality?	Little effect on water quality. Terrestrial species.	L	M
7. Increase soil erosion?	Little effect on soil erosion as parasite attached to host, not soil. Only in soil for a couple of days post germination until secure attachment to host.	L	M
8. Reduce biomass?	Biomass may increase slightly as parasite adds floral mass to host.	L	L
9. Change fire regime?	Small, or negligible, effect on fire risk.	L	L
Community Habitat
10. Impact on composition (a) high value EVC	EVC= Plains Woodland (BCS= E); CMA= Mallee; Bioreg= Murray Mallee; CLIMATE potential= Medium. Minor displacement of spp. within host’s strata/layer.	ML	M
(b) medium value EVC	EVC= Riverine Grassy Woodland (BCS= D); CMA= Mallee; Bioreg= Murray Mallee; CLIMATE potential= Medium. Minor displacement of spp. within host’s strata/layer.	ML	M
(c) low value EVC	EVC= Heathy Mallee (BCS= LC); CMA= Mallee; Bioreg= Murray Mallee; CLIMATE potential= Medium. Minor displacement of spp. within host’s strata/layer.	ML	M
11. Impact on structure?	Minor, or negligible, effect on <20% of the floral strata/layers present; usually only affecting one of the strata. Likely to have an effect on host species layer only.	L	M
12. Effect on threatened flora?	Not mentioned specifically in literature reviewed.	M	L
Fauna
13. Effect on threatened fauna?	Unknown.	M	L
14. Effect on non-threatened fauna?	Unknown.	M	L
15. Benefits fauna?	Unknown.	M	L
16. Injurious to fauna?	No effect.	L	L
Pest Animal
17. Food source to pests?	Unknown, but doubtful.	M	L
18. Provides harbor?	No harbour for pest species.	L	L
Agriculture
19. Impact yield?	Quantity of yield reduction not found in literature reviewed, although authors, such as Parsons and Cuthbertson (’92), allude to it occurring, therefore it is reasonable to conclude that it must be somewhat significant as it is regularly mentioned as a weed of several economically important crops. Parasitises lucerne, flax and linseed (Parker and Riches, ’93). Parasitises alfalfa, asparagus, clovers, cucurbits, and onions (UC ’76).	MH	M
20. Impact quality?	Quality of yield reduction not found in literature reviewed, however, assessor concludes that it must be somewhat significant as it is regularly mentioned as a weed of several economically important crops. Parasitises lucerne, flax and linseed (Parker and Riches, ’93). Parasitises alfalfa, asparagus, clovers, cucurbits, and onions (UC ’76).	MH	Ml
21. Affect land value?	Decrease in land value not found in literature reviewed, however, assessor concludes that it must be somewhat significant as it is regularly mentioned as a weed of several economically important crops. Parasitises lucerne, flax and linseed (Parker and Riches, ’93). Parasitises alfalfa, asparagus, clovers, cucurbits, and onions (UC ’76).	H	Ml
22. Change land use?	Downgrading of the priority land use. Parasitises lucerne, flax and linseed (Parker and Riches, ’93). Parasitises alfalfa, asparagus, clovers, cucurbits, and onions (UC ’76).	MH	Ml
23. Increase harvest costs?	Minor increase in cost of harvesting (contaminating seeds usually left, contaminating vegetation removed). Parasitises lucerne, flax and linseed (Parker and Riches, ’93). Parasitises alfalfa, asparagus, clovers, cucurbits, and onions (UC ’76). Potential seed contaminant. (GRIN, 2006)	M	Ml
24. Disease host/vector?	Not known to be a host/vector itself.	L	L

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	Opportunistic germinator, can germinate whenever water is available. No specialised germination requirements to ensure that the host is present at germination. (Parker and Riches, ’93) However, a proportion of seeds have a dormancy range to ensure that germination is staggered, and so, increase the likelihood of suitable hosts being present at germination. (Ibid.; UC ‘76) Requires constant moisture. Optimal season for germination is spring once temperatures are above 15◦C. (Parker and Riches, ’93) Given favourable conditions, C. indecora seed can even germinate whilst still in the fruit (UC,’76)	H	MH
2. Establishment requirements?	Requires very specific factors to establish. Requires host species to be immediately adjacent in order to establish and attach to host in < 24 hours (DeLange, ’05). Regardless of depth of germination, the root makes no further growth once the shoot has emerged, and serves only to support the shoot [for < 24 hours] until it locates a [suitable] host... by circumnutation. (Parker and Riches, ’93)	L	MH
3. How much disturbance is required?	Establishes in highly disturbed natural ecosystems. Grows on roadsides and in moist fields (Hickman, ’93)	ML	MH
Growth/Competitive
4. Life form?	Climber. Parasitic vine/climber. Not limited to one host (UC, ’76) Family : Cuscutaceae. Annual. (Ohio Department of Natural Resources Webpage, 2004). Parasitic on a number of hosts. (Lives on several different hosts, woody and herbaceous. Leafless, rootless, annual. (Ibid.) Known sometimes to kill small herbaceous hosts. (Uvalde Research Website, 2000.) Attaches to host in < 24 hours. (DeLange, ’05)	ML	ML
5. Allelopathic properties?	None mentioned in literature reviewed.	L	L
6. Tolerates herb pressure?	Consumed and recovers slowly. Reproduction inhibited by herbivory but still capable of vegetative production; weed may still persist. Herbivorous damage to Cuscuta sp. By insects of the Smicronyx sp. (Curculonidae) (weevils), Melanagromyza sp. (Agromyzidae) (leaf-mining flies), and Herpystis sp. (Tortricidae) (tortricid moths). (Parker and Riches, ’93) Fungal damage by Alternaria sp., Curvularia sp., and Colletotrichum sp. (Ibid.) NB No definitive data available yet from biocontrol studies in Pakistan and the former USSR, BUT it seems apparent that the fungal pathogens are efficacious on all members of the Cuscuta genus. This MAY adversely effect the native species of Cuscuta.	ML	MH
7. Normal growth rate?	Rapid growth rate that will exceed most other species of the same life form. Attaches to host in less than 24 hours. (DeLange, ’05) Grows fairly rapidly to take best advantage of nutrients produced by host, reproduce to seed-set, before killing host.	H	M
8. Stress tolerance to frost, drought, w/logg, sal. etc?	May be tolerant of stress. Moisture not a limiting factor, although drought does cause stress. (Parker and Riches, ’93)	L	MH
Reproduction
9. Reproductive system	Sexual and vegetative. Bisexual plants. Produces berry-like capsules (Hickman, ‘93) that contain four seeds each (DeLange, ‘05). New individuals can be benerated from scraps broken off a parent plant (UC, ’76)	H	MH
10. Number of propagules produced?	1,000 – 2,000. Flowers produced in cyme (rarely solitary). Very numerous. Each flower may produce a berry, each berry contains four seeds. (DeLange, ‘05). Estimate ~ 1,000 – 2,000 seeds per plant.	MH	M
11. Propagule longevity?	Greater than 25% of seeds survive 10-20 years in the soil. Parker and Riches (’93) note that viable seeds can easily survive for at least 10 years in the field (> 50 years in dry storage).	MH	MH
12. Reproductive period?	Mature plant produces viable propagules for only one year. Plant is annual; therefore plant produces viable propagules for less than one year.	L	H
13. Time to reproductive maturity?	Reaches maturity and produces viable propagules in under a year. Plant is annual; therefore plant reaches reproductive maturity, and sets seed in under one year.	H	H
Dispersal
14. Number of mechanisms?	Propagules spread by water, attachment, OR accidental human dispersal. Spread of contaminated seed in lucerne, flax and linseed. (Parker and Riches, ’93; GRIN ‘06) Viable seeds in farmyard manure as seeds of Cuscuta spp. are known to survive alimentary passages of domestic animals (Parker and Riches, ’93) and kangaroos (Parsons and Cuthbertson, ’92). As seeds coats are partially digested, … the seeds often have lowered dormancy periods are ready to germinate immediately … [with a ready source of fertiliser for potential hosts]. (Parker and Riches, ’93 UC (’76) list seed dispersal by water, animal attachment, contaminated crop seed, inadvertent movement of stem fragments.	MH	MH
15. How far do they disperse?	Very likely that at least one propagules will disperse greater than one kilometre. Attachment is a means of dispersal. Seeds 1.2 – 1.8 mm long.	H	L

References

DeLange, G & DeLange, A. (2005) Largeseed Dodder, Cuscuta indecora. Arizona Wild Flowers Webpages. http://delange.org/Dodder/Dodder.htm [Accessed 19 Dec., 2005.]

GRIN (2006) USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network (GRIN) [Online Database].

National Germplasm Resources Laboratory, Beltsville, Maryland. URL: http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?12685
[Accessed 19 Dec., 2006.

Hickman, J. C. (Ed.) (1993) The Jepson Manual Higher Plants of California. (web version at: ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?3397,3398,3408 [Accessed 19 Dec., 2006.]

Lundell, CL. (1943) Flora of Texas. Vol. 3. Part II: ANACARDIACEAE, CYRILLACEAE, AQUIFOLIACEAE, Genus Cuscuta, CONVOLVULACEAE. Southern Methodist University, University Press in Dallas, USA.

Ohio Department of Natural Resources Webpage. (2004) http://www.ohiodnr.com/dnap/Abstracts/C/cuscinde.html [Accessed 19 Dec., 2006.]

Parker, C and Riches, CR. (1993) Parasitic Weeds of the World: Biology and Control. Castlefield Press Ltd., Kettering, UK.

Parsons WT and Cuthbertson EG. (1992) Noxious Weeds of Australia. Inkata Press, Australia.

University of California. (1976) Cuscuta spp. (Dodder): A Literature Review of Its Biology and Control. Division of Agricultural Sciences, Bulletin 1880. California, USA.

Uvalde Research and Extension Centre Website. (2000) Texas A&M University System. http://uvalde.tamu.edu/herbarium/cucu.html [Accessed 19 Dec., 2006.]

Global present distribution data references

Australian National Herbarium (ANH) 2006, Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research. [Accessed 19 Dec., 2006.] http://www.anbg.gov.au/avh/

DeLange, G & DeLange, A. (2005) Largeseed Dodder, Cuscuta indecora. Arizona Wild Flowers Webpages. http://delange.org/Dodder/Dodder.htm [Accessed 19 Dec., 2005.]

Global Biodiversity Information Facility (GBIF) 2006, Global biodiversity information facility: Prototype data portal. [Accessed 19 Dec., 2006.] http://www.gbif.org/

Hickman, J. C. (Ed.) (1993) The Jepson Manual Higher Plants of California. (web version at: ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?3397,3398,3408 [Accessed 19 Dec., 2006.]

Missouri Botanical Gardens (MBG) 2006, w3TROPICOS, Missouri Botanical Gardens Database. [Accessed 19 Dec., 2006.] http://mobot.mobot.org/W3T/Search/vast.html

Ohio Department of Natural Resources Webpage. (2004) http://www.ohiodnr.com/dnap/Abstracts/C/cuscinde.html [Accessed 19 Dec., 2006.]

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