Agriculture is, and will remain for years to come, the main driver of economic development in Africa, he says in an article posted on SciDev.net. Vegetables such as cowpea in West Africa and the common bean in East Africa are an important source of cash and nutrition.

Vegetable and horticultural crops will soon become more important due to increasing urbanisation. But they are plagued by insect pests and diseases that can reduce yields by up to 80 per cent.

Farmers often resort to using chemical pesticide sprays to mitigate the problem. But pesticides are usually applied without taking basic safety precautions such as protecting oneself against the spray mist, or using the correct dosage and intervals between applications.

The problem is compounded by aggressive selling strategies, where retailers target barely literate growers to market toxic pesticides of dubious quality that are sometimes inappropriate — for example destined for use on cotton, not vegetables.

As a result pesticides can pose risks to the health of consumers, the environment, and producers. They include acute and chronic side effects including the development of skin and neurological disorders. And indiscriminate use of broad-spectrum insecticides can wipe out pests' natural enemies.

Most growers ignore the natural ways in which pests and disease can be managed. Yet biopesticides — derived from plants as well as microorganisms such as viruses and fungi — have virtually no adverse impact on environmental and human health.

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