

Sorghum [Sorghum bicolor (L.) Moench] is the 5th most important cereal crop worldwide. The plant is mainly cultivated in dryland areas of Africa and Asia, and also in the Americas. Average grain yields range from 800 kg ha-1 in Africa to 3400 kg ha-1 in America. Parasitic weeds of the genus Striga are the major biotic constraint to agricultural production in sub-Saharan Africa. Striga hermonthica and Striga asiatica parasitize mainly cereals. Yield losses can, especially in the presence of additional drought stress, attain 100%. In comparison with chemical, mechanical and biological Striga control methods, the cultivation of crop cultivars resistant to Striga is of particular advantage to farmers, since it does not require specifi c investments in materials or labor.