and export of horticultural crops has continued to increase over the years (FAO, 2004c). Export markets offer strong prospects for expanding the horticultural industry in SSA.

Production constraints for horticultural crops in SSA include pests and diseases and lack of access to improved high yielding plant varieties. Horticultural crops have exacting requirements. It is necessary for producers to use good cultural and agronomic practices in order to produce high quality and value products for export.

Coffee. Coffee is an invigorating stimulant taken as a beverage worldwide. Owing to its high market price coffee is grown by farmers in SSA mainly for export since around the end of the 19th century. As a cash crop, it has contributed to improving the economic status of many resource-poor farmers in SSA. Arabian and robusta high quality coffee are cultivated. Coffee production up to the first half of the 20th century was mainly practiced by small-scale farmers. Coffee production continued to increase gradually over the years with the small holders playing an important role in overall production. In Kenya, for instance, coffee production increased from 14,000 to 45,000 tonnes between 1952 and 1966. Coffee production increased to about 1.2 million tonnes in the 1980s and has remained more or less consistent since then. East Africa has consistently been the major producer of coffee in SSA with Ethiopia and Uganda as lead coffee producing countries (FAO, 2004c).

The main reasons for increased production of coffee in SSA over the years have been due to increases in the area of harvested coffee and increases in yield due to the availability and use of improved seeds, timely and adequate application of fertilizers and application of appropriate pest control measures.

2.1.4 Harvest and postharvest management
Storage of agricultural products may be done for consumption on a future date or to fetch more money in times of scarcity. Agricultural products can be stored to provide seeds for subsequent planting. Government may also store surplus agricultural products for price stabilization through product release in times of scarcity (Dike, 1994).

Pests and diseases are major limiting factors to successful storage. Several storage insect pests start their infestation in the field and are then carried into the store (Ajayi and Lale, 2001). Timing of harvest has been reported as a cultural method that can be employed in the control of storage insect pests (Olubayo and Port, 1997; Kabeh and Lale, 2004). Crops that are promptly harvested at maturity are less attacked by storage insect pests than those that are left longer in the field after maturity. Prompt harvesting of crops at maturity has been recommended and in practice since the latter half of the 20th century, resulting in better food security.

Losses of up to 30-100% have been recorded on stored food in the absence of efficient insect pest control measures (Caswell, 1984). When grains are not properly dried, they are predisposed to attack by insect pests and diseases. Insect pests and diseases result in a loss of seed viability and modification of the biochemical composition of affected grains (Dike, 2005). The most serious effect of disease in-

fection is the production of mycotoxins in attacked grains. Consumption of such grains may result in disease known as mycotoxicoses (Schilling and Misari, 1992; Marley, 1996). Drying of grains using fire and solar disinfestations has been used in traditional farming systems by resource-poor and small-scale farmers. Storage in air-tight containers, such as metal drums and plastic containers is an old practice, which causes insects to die of asphyxiation (Bailey, 1954). Another common traditional method of postharvest management is the use of ash from cooking fire.

AKST has made available more effective postharvest management measures, which include the integration of storage pest resistant varieties with solar disinfestation and the use of air-tight containers. Chemicals such as aluminum phosphide have been used by large-scale farmers to disinfest crops for storage. The toxic effects of these chemicals demand that they be used judiciously and has also led to the search for alternatives in postharvest management. Oils and powders of plant materials such as neem, eycalyptus, citrus peel, etc., have been found to control postharvest insect pests (Dike and Mshelia, 1997). Several of these plant materials are readily available and are currently in use in postharvest management.

Practicing good postharvest management is needed to keep good quality seed for planting and to secure the harvest, ensuring availability of food and reduction of poverty. In SSA, the use of an integrated approach in postharvest management has not been a common practice, especially among small-scale farmers, mainly due to poverty and lack of education. The training of farmers through farmer field schools, for example, and the provision of soft agricultural loans could go a long way toward improving the technical know-how and financial status of these farmers. Some governments in SSA have in the past and are currently providing agricultural loans to farmers, but these loans are not sufficient to meet demand. Farmer field schools have been supported by FAO and are currently operated in some countries in SSA. Considering economic constraints within SSA, improvements on existing local and traditional knowledge currently available to most resource-poor farmers in the region should be encouraged as a low-cost option for improvements to productivity.

2.1.5 Pest and disease management
Agricultural production in sub-Saharan African agroecosystems is greatly affected by pests such as insects, nematodes, fungi, rodents, birds, weeds, viruses and bacteria. The parasitic weed Striga hermonthica commonly known as “witchweed” infests as much as 40 million ha of farmland in SSA and causes losses ranging from 20% to 100% (AATF, 2005).

Over the years, in order to reduce yield losses due to pests and weeds, farmers traditionally have selected welladapted, stable crop varieties and used cropping systems in which two or more crops are grown in the same field at the same time. They have commonly used wood ash, cattle urine, ground hot pepper and some repulsive plants for insect pest and disease control. Cats were used for rat control as well as flooding or smoking-out of rat tunnels. Practices such as tillage (plowing and hoeing), flooding, digging and burning contribute to pest reduction and cultural measures