The harvesting periods in West Africa, where two crops a year are possible, are August-September for early maize and December-January for late maize. In West Africa the major cereals grown are sorghum, rice, maize, millet and wheat. For different uses, different types and varieties are cultivated over most parts of West Africa. Guinea corn is one of the most common cereals in West Africa, where it is eaten in one form or another by many more people than are the rest of the cereals put together. Cowpeas, an annual legume, is the most important, cheapest and most widely consumed legume crop in West Africa. The crop is slightly drought resistant, and it becomes highly susceptible to a number of root diseases as well as pests in the wetter tropical climate in the southern parts of West Africa. Control of pests is by spraying or dusting with insecticides and the practice of crop rotation.