The Nation (Nairobi)

26 May 2005

Kenya: Growing Cabbage Without Pesticides

Nairobi — Now farmers can grow cabbages without the use of pesticides at a much lower cost and an increased yield of Sh 21,000 per hectare.

The International Centre for Insect Physiology and Ecology (Icipe) and the Kenya Agricultural Research Institute (Kari), have successfully introduced an exotic wasp that has now almost eliminated one of cabbages' most destructive pests.

The wasp introduced about three years ago has proven successful in five different places in Kenya - Wundanyi, Kanari, Kamburu, Kisii and Katheri in Meru.

A farmer in Wundanyi, where the wasps had been released, Mr Simon Charo, said since the introduction of the insects on his farm he no longer applied chemicals to his cabbages and the yield had gone up remarkably.

"Before, I was spending up to Sh5,000 on pesticides which were less effective than the wasps, I am now planning to expand the area under cabbages from half to two acres soon," he told Horizon at his farm last week.

In 2002 Icipe introduced Diadegma semiclausum the exotic parasitic wasp to control the Diamondback Moth - a pest which can lead to a 100 per cent crop loss if not controlled.

The project commenced with a survey in the major cabbage growing areas in Kenya, Uganda and Tanzania, which showed that existing enemies were not providing a big enough impact in control of the moth.

Icipe therefore imported the wasp, already being used in a number of countries in South East Asia (Taiwan, Indonesia, Mainland China) where most farmers have stopped using pesticides.

The logic behind this technology, says Dr Lohr, is that the wasp is the moths' natural enemy. The process begins when the wasp stings the moth's larvae where it lays its eggs. The eggs in turn hatch and feed on the moth's internal organs leading to the death of the pest.

The biological pest control technology, say Dr Lohr, will while cutting down on investment costs, reduce environmental pollution occasioned by spraying and effects of the same on the environment. Mr Gatama Gichini, a senior research assistant at ICIPE, said that although the project had recorded such great success, a few farmers in the area were still using pesticides. He said that in as much as the technology had reached their neighbours some did not know of it yet.

He added that this lack of awareness combined with the farmers prejudiced approach to farming was a major impediment to the full success of wasp propagation.

The wasp can now, three years after release, be found within a 20 km radius of the release point. This is a positive research discovery as it can therefore be concluded that the wasp is not affected by physical barriers such as topography.

Dr Lohr who said that the only negative impact that the wasp could have on the cabbage farmers was an increase in cabbage production. This would increase the supply of cabbage thereby having a negative effect price.

He advised the farmers to adopt a planting pattern that does not lead to a glut in the market. Mass breeding of the parasitic wasps, and their release in all the important cabbage-growing areas is being handled by Kari.

Dr Lohr says although the wasp has been successful against the wasp there are several other peripheral cabbage pests that also need to be controlled and Icipe is already designing appropriate tools for them.

Icipe's biological control experts predict that introduction of parastoids will reduce yield loss in individual farms by up to 30 per cent, increasing the average yield per hectare per year by 2.1 tonnes, translating to an extra Sh 21,000 per hectare and a total annual benefit estimated Sh332 million for the whole economy in a completely elastic demand and supply situation.

Cabbages and kales are the most important vegetables in the region especially for lower income groups. The importance of these vegetables is probably greater in Kenya than other African countries, where, according to the Ministry of Agriculture, they occupy over 18,000 hectares.

Eaten daily, either raw in salads, steamed, boiled or fried, cabbages and their cousin kale serve as important cash-generating crops.

Grown in all of Kenya's eight provinces, with Rift Valley and Central province jointly making-up 82 per cent of the total production, cabbages have the potential of being an economic enterprise, and could contribute to poverty reduction. So far, however, cabbage production has generated less than satisfactory income. The average yield of 13.8 tonnes a hectare a year is very low, and at an estimated Sh10 a kg generates about Sh138,000 a hectare, working out to Sh2.61 billion a year for the entire production in Kenya.

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