Striga species are parasitic weeds attacking the roots of tropical cereal crops, particularly sorghum and millet but also maize, sugarcane and cowpea. They not only sap the host of water and nutrients but also have a poisoning effect which can result in complete crop failure. Damage is done before the weed emerges and cannot be prevented by traditional hand weeding.
Striga affects the poorest of farmers, those least able to change their cropping or use advanced methods of control. Traditionally the problem has been avoided by moving village when the land becomes severely infested. Greater pressure on land now prevents this solution and Striga is contributing increasingly to famine in the west African Sahel, Ethiopia etc. The most promising approach is the introduction of resistant crop varieties but few have yet been developed.
Striga species occur mainly in the semi-arid tropics and affect many million acres of crops across northern tropical Africa, eastern and southern Africa, Indian Ocean, south-west Arabia and the Indian sub-continent. The problem is most acute under conditions of low soil fertility and erratic rainfall.
Striga, also known as witch weed, is a parasitic plant that attacks sorghum. Although this isn't a problem in the United States, it is in the countries of sub-Saharan Africa, where sorghum is the second most important food crop behind corn. Striga destroys 40 percent of Africa's annual sorghum crop, which is worth about $7 billion per year. In Ethiopia and Sudan, the losses are as high as 100 percent in some areas.