The genus Striga: a witch profile

The genus Striga comprises about 30 obligate root-parasitic plants, commonly known as witchweeds. In particular, S.hermonthica, S.asiatica and S.gesnerioides cause immense losses to major stable crops in sub-Saharan Africa. Most Striga species parasitize grass species (Poaceae), but Striga gesnerioides has evolved to parasitize dicotyledonous plants. Aspects of phylogeny, economic impact, parasitic life style and molecular discoveries are briefly reviewed to profile one of the main biotic constraints to African agriculture. TaxonomyStriga Lour.; Kingdom Plant; Division Angiospermae; Clade Eudicots; Order Laminales; Family Orobanchaceae. Important hostsSorghum Moench., maize (Zea mays L.), rice (Oryza L.), sugarcane (Saccharum L.), pearl millet [Pennisetum glaucum (L.) R. Br.], cowpea [Vigna unguiculata (L.) Walp.]. Disease symptomsStunted growth, drought-stressed-like appearance, in severe cases chlorosis and necrosis. Economic importance1 billion $US per annum. Disease controlHand weeding, breeding, chemical control, intercropping with catch or trap crops. Useful webpageshttp://ppgp.huck.psu.edu; http://striga.psc.riken.jp