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   Striga asiatica (herb)    
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         General Impact

    Globally, parasitic weeds of the genus Striga have a gigantic impact on human welfare because their hosts are often subsistence crops in marginal areas of agriculture in semi-arid and sub-humid tropical regions which result in little or no food at all for millions of subsistence farmers and consequently aggravate hunger and poverty. Infestations reduce yields and contaminate crops. Yield losses of 5-15% are common, although locally, under severe infestations, losses can far exceed this amount. S. asiatica impairs photosynthesis of susceptible maize hosts through limiting stomatal conductance and sensitizes infested plants to photo inhibition. Symptoms in host plants include stunting, chlorosis, and wilting (CDFA, 2006; Elzein and Kroschel, 2004; Invasive.org, 2006; and Gurney et al. 2001).

    S. asiatica attacks important crops such as: corn, sorghum, sugar cane, and rice. It is also known to parasitize certain weedy grasses. S. asiatica robs nutrients and moisture by tapping directly into a host's root system. The host expends energy supporting S. asiatica growth at its own expense. S. asiatica will grow in the presence of grassy weeds as well as grass host crops, so cotton, peanut, or soybean fields-along with home gardens or idle land-may harbor this species (APHIS, 2000).

    Federal and state quarantine and eradication programs have been able to greatly reduced the area of S. asiatica infestation since 1955 but with at a great economic cost (CDFA, 2006).




         Location Specific Impacts:
    South Africa English 
    Agricultural: Striga is one of the most serious constraints to cereal production in sub-Saharan Africa (Gurney et al 2001).
    Uganda English 
    Agricultural: Striga is one of the most serious constraints to cereal production in sub-Saharan Africa (Gurney et al 2001).
    Zambia English 
    Agricultural: Striga is one of the most serious constraints to cereal production in sub-Saharan Africa (Gurney et al 2001).
    Zimbabwe English 
    Agricultural: Striga is one of the most serious constraints to cereal production in sub-Saharan Africa (Gurney et al 2001).



ISSG Landcare Research NBII IUCN University of Auckland