• The forage grasses, Pennisetum purpureum (Napier grass) and Sorghum vulgare sudanense (Sudan grass), attract greater oviposition by stem borers than cultivated maize.

• History offers many examples of serious economic loss and suffering arising from reliance on monocultural systems (see table 3). Among the best known are the potato famine of Ireland during the nineteenth century, a wine-grape blight that wiped out valuable vines in both France in the nineteenth century and the United States in California in the 1970s and 1980s, a virulent disease (Sigatoka) that damaged extensive banana plantations in Central America in recent decades and a devastating mould that infested hybrid maize in Zambia.

• These farmers now apply little basal fertiliser to soyabean preferring to raise the crop on residual fertility from well-fertilised maize in the rotation.