Striga gesnerioides an its hosts, the cowpea: Interaction and methods of control

Cowpea (Vigna unguiculata (L.) Walp.) is an important legume crop in subsah arian Africa. However, its cultivation is threatened by the parasitic weed Striga gesnerioides (Willd.) Vatke, which causes considerable yield losses. Striga gesnerioides is an obligate parasite with low photosynthetic activi ty. Its seeds germinate in response to specific germination stimulants exud ed by host roots. After germination, an haustorium is formed through differ entiation of the radicular apex. A vascular connection is subsequently esta blished, allowing the parasitic weed to absorb water and nutrients that are essential for its development. Control of S. gesnerioides is difficult to achieve because of the intimate association between the parasitic weed and its host. The use of resistant cowpea cultivars, in combination with approp riate cultural practices, is probably the easiest and most effective method to control S. gesnerioides and achieve long term reduction of its seed ban k in the soil.