Striga asiatica

{{Short description|Species of flowering plant}} {{Speciesbox |name = Asiatic witchweed |image = Strigaasiatica.jpg |genus = Striga |species = asiatica |authority = (L.) Kuntze |synonyms = ''Striga lutea'' }}

'''''Striga asiatica''''', the '''Asiatic witchweed''' or the '''red witchweed''',<ref name=keys>{{cite web|url=https://keys.lucidcentral.org/keys/v3/eafrinet/weeds/key/weeds/Media/Html/Striga_asiatica_(Red_Witchweed).htm|title=Striga asiatica (Red Witchweed)|accessdate=24 April 2019}}</ref> is a hemiparasitic plant in the family Orobanchaceae. It is native to Asia and sub-Saharan Africa,<ref name=Cochrane>{{cite journal|author=Cochrane, V.|author2=Malcolm C. Press|year=1997|title=Geographical Distribution and Aspects of the Ecology of the Hemiparasitic Angiosperm ''Striga asiatica'' (L.) Kuntze: A Herbarium Study|journal=Journal of Tropical Ecology|volume=13|pages=371–380|issue=3|doi=10.1017/S0266467400010579|jstor=2560290|url=http://eprints.whiterose.ac.uk/1581/1/pressmc1.pdf}}</ref> but has been introduced into other parts of the world including Australia and the United States. Asiatic witchweed is a serious agricultural pest, as it parasitises important crop species, including corn, rice, sorghum, and sugar cane, often causing substantial yield reductions.<ref name=keys/>

While it is native to Africa and Asia, it is invasive in farmlands of Kenya, Tanzania and Uganda.<ref name="keys" />

In the US, this witchweed was discovered in the Carolinas in 1956.<ref>{{cite journal|author=•Werth, C.R.|author2=Riopel, J.L. Riopel|author3=Gillespie, N.W.|year=1984|title=Genetic uniformity in an introduced population of witchweed (Striga asiatica) in the United States|journal=Weed Science|volume=32|issue=5|pages=645–648|jstor=4043983|doi=10.1017/S0043174500059725}}</ref> It is considered an invasive agricultural pest, and a vigorous eradication campaign has reduced the affected area by 99% [from {{convert|450000|acre|km2|-1}} to about {{convert|3400|acre}}].<ref>{{cite journal|author=Spallek, T.|author2=Mutuku, J.M.|author3=Shirasu, K.|year=2013|title=The genus Striga: A witch profile|journal=Molecular Plant Pathology|volume=14|issue=9|pages=861–869|doi=10.1111/mpp.12058|pmid=23841683|issn=1464-6722|pmc=6638688}}</ref>

thumb|''Striga asiatica''

Biological control can be achieved by growing a ''Desmodium'' (tick-trefoil) undercrop (see push–pull technology). The trefoil can be used as green manure or animal fodder after the harvest.<ref>{{cite web|url=http://www.plantsinusa.com/show/plant/Asiatic-Witchweed/84208|title=Asiatic Witchweed|accessdate=24 April 2019}}</ref>

==Description== ''S. asiatica'' seedlings are not visible above ground, but white succulent shoots can be found attached to host roots. Mature plants have green foliage above ground, sparsely covered with coarse, short, white, bulbous-based hairs. Mature plants are normally {{convert|15|–|30|cm}} tall, but have grown to {{convert|60|cm}}. Leaves are nearly opposite, narrowly lanceolate, about {{convert|1|–|3|cm}} long, with successive leaf pairs perpendicular to one another. Flowers, produced in summer and fall, are small (less than {{convert|1.5|cm}} in diameter), sessile and axillary, with a two-lipped corolla, occurring on loose spikes. Flower colour varies regionally, from red, orange, or yellow in Africa to pink, white, yellow, or purple in Asia. The flowers give way to swollen seed pods, each containing thousands of dustlike seeds. Underground stems are white, round with scale-like leaves, turning blue when exposed to air. The roots are succulent, round, without root hairs, and found attached to a host species root system.<ref>{{cite web|url=https://articles.extension.org/pages/62641/striga-asiatica-witchweed|title=Invasive Species: Striga asiatica, Witchweed|date=9 February 2012|accessdate=24 April 2019}}</ref>

==References== {{Reflist}}

==Sources== *Simberloff, Daniel. 2003. Eradication - preventing invasions at the outset. Weed Science 51:247–253. *[http://www.westafricanplants.senckenberg.de/root/index.php?page_id=14&id=1508 Striga asiatica] in Brunken, U., Schmidt, M., Dressler, S., Janssen, T., Thombiano, A. & Zizka, G. 2008. West African plants - A Photo Guide. Forschungsinstitut Senckenberg, Frankfurt/Main.

==External links== *[https://www.invasivespeciesinfo.gov/profile/witchweed Species Profile- Witchweed (''Striga asiatica'')], National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Witchweed. *{{cite web | title=Red witchweed | website=Business Queensland | date=2016-10-12 | url=http://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/land-management/health-pests-weeds-diseases/weeds-diseases/invasive-plants/prohibited/red-witchweed | access-date=2021-09-28}}

Category:Orobanchaceae Category:Parasitic plants Category:Botanical taxa named by Carl Linnaeus