The potential for silk in Africa

Silk production is typically associated with Asia, where silk processing was first developed over 4,500 years ago in China. The growing demand for silk in recent years has created opportunities for silk production in other parts of the world, including Africa. However, silk is a high value product and it is essential that care and quality control are deployed in all stages of production. Sericulture is the cultivation of silkworms and the production of their silk cocoons. Moriculture is the cultivation of mulberry bushes, the leaves of which provide the food of the silkworm. Silk production in most African countries is still in its infancy, but the combined agricultural practices of mori- and sericulture offer many unique opportunities for further development of the industry. Success has been achieved in Zimbabwe after a small-scale pilot project in 1992 was launched by Manicaland Development Association with the help of the UK-based Intermediate Technology Development Group (ITDG). This project was established on the marginal lands of the Eastern Highlands where the soil is too infertile to produce crops. The scheme demonstrates that mulberry bushes achieved good soil erosion control; that silk production is ideally suited to small-scale production; and that sericulture is labour intensive thereby providing employment opportunities and increased incomes for many rural poor, especially women, in a wide range of activities. Silk production starts with the cultivation of mulberry bushes. There are many varieties of mulberry. The white mulberry, Morus alba, is grown extensively for its leaf to feed silkworms but, of 1,200 varieties of white mulberry grown throughout the world, only a few have proved to be ideal for silkworm rearing. The white mulberry can be successfully cultivated in almost all climatic zones, in temperate as well as tropical areas, under either rainfed or irrigated conditions and some varieties can even thrive on arid, marginal lands. The growth of the tree is affected by temperature in cooler climates but in tropical regions, where there is good rainfall, leaves can be harvested up to six times a year. Mulberry can be propagated in a number of ways (grafting, layering or seeping) but the simplest and most economical is through the use of cuttings. This vegetative method of propagation also retains the desired characteristics in the plants. Mulberry grows quite rapidly and within six months the cuttings, which will have been established in a plantation, grow sufficient leaf to start harvesting. A one hectare plantation, for example, planted with 10,000 one-year mulberry bushes at 1m x 1m spacing can, by rotating the leaf picking, sustain a six month rearing season and produce up to 250 kg of reeled raw silk. It is essential to grow the most appropriate variety of white mulberry for a given situation in order to supply a constant source of nutritive leaf to feed the silkworm larvae and to produce the best 'A' qualify cocoons the prime objective. But once established, and with proper maintenance, mulberry remains productive for about 15 to 20 years. In an integrated farming system cut grass, straw and pruned mulberry twigs can help control weeds and reduce water loss from the soil. Farmyard manure and compost can be regularly applied to maintain humus content, soil structure, and micro-nutrients whilst leguminous crops such as soya bean can be intercropped, at less intensive spacing, to provide essential nitrogen for good leaf growth. There are many types of the silk moth, Bombyx mori, but those that reproduce twice a year, the so-called bivoltine variety, are best suited to the climate of most African countries. Traditionally the best eggs come from egg producing centres (grainages) in Japan where, over a period of many years, hybrid varieties of silk moth have been developed to produce larvae which generate high yield cocoons. However, good quality eggs, or seed as they are called, are also available from India and it is these which have been used in Zimbabwe. More recently, small quantities of seed have also been available from the eastern Transvaal, South Africa. Rearing silkworms is a labour intensive operation. However, careful planning allows for the use of local resources in the construction of rearing houses. In Zimbabwe the rearing houses have been built by traditional methods using handmade bricks and local thatch. It is vital that the buildings are well-ventilated and rodent proof. The rearing of the silkworms themselves also gives opportunities for training in the care and handling of eggs, larvae and cocoons. The cocoons are usually sold to reelers who then process the silk, but results from the Malwatte Silk Enterprise at Marondera, Zimbabwe, show that it is possible for a group of people to manage all stages of processing from rearing the silkworms to weaving the cloth on hand looms and then selling the silk locally. These findings are particularly encouraging as the opportunities for off-farm employment increase with the introduction of all the post-cocoon production activities. Each activity of reeling, twisting the silk (throwing), dyeing and weaving creates a series of opportunities for market levels and value is added to the silk at each stage. Several other African countries are eager to start their own sericulture industries although most of the projects aim to export cocoons or raw silk rather than produce cloth. Transporting 'feather-light cocoons is not particularly practical or profitable and any raw silk must be of a high enough quality to compete in the international market. This could be achievable with a diligent approach to rearing and reeling but options of producing cloth locally should be explored first. Research is also being undertaken into several wild varieties of silk moth native to Africa. Two indigenous species found in Southern Africa, for instance, produce a soft, natural khaki-coloured silk. So the potential for sericulture in Africa is one that has to be seriously considered. Further information: FAO Agricultural Services Bulletins: 73/1 Mulberry cultivation; 73/2 Silkworm rearing; 73/3 Silkwork egg production; and 80 Sericulture training manual. A handbook has just been published by Intermediate Technology Publications Sericulture and silk production by Prabha Shekar and Martin Hardingham (see this issue Bookshelf). Lists of silkworm seed suppliers silkworm rearing equipment and small-scale reeling machinery suppliers are available from Martin Hardingham, The Green Long Sutton, Somerset TA10 9HS UKSilk production is typically associated with Asia, where silk processing was first developed over 4,500 years ago in China. The growing demand for silk in recent years has created opportunities for silk production in other parts of the world,..