Farmers in western Kenya have known Striga for more than one hundred years. Lately it has become a real threat to cereal production in Nyanza and Western Provinces. Factors that affect the build-up of Striga include: increasing land pressure caused by a steadily growing population, intensely cultivated soils and decreasing soil fertility. The problem is more widespread and serious where both rainfall and soil fertility are low (and elevation is below 1,700 m). It is estimated that 160,000 ha of farmland in the Lake Victoria basin are currently infested with Striga. There are over 50 species of Striga but only two major species are found in Kenya. These are Striga hermonthica in western Kenya and Striga asiatica in the coastal areas. This guide will only deal with Striga hermonthica as it focuses on the farming system common to western Kenya. Nevertheless, the information contained herein should also have wide-scale application for controlling Striga asiatica.