Originally published on cgiar.org by:International Institute of Tropical Agriculture (IITA) on Mar 7, 2007

Resource-poor farmers in the humid forest zone of West and Central Africa suffer heavy losses in plantain cultivation from numerous pests and diseases. Nematodes are amongst the most damaging pests, causing many plants to fall before an edible bunch of fruit is produced. Farmers in Cameroon and Nigeria, however, have now the means to prevent these pests from damaging their crop by applying hot water to treat plantain and banana suckers to kill nematodes and rid their farms of nematodes, bacterial, and fungal diseases. Those who apply the hot water treatment have not only controlled the nematodes and root rot diseases but have doubled the yields.

Farmers do not see nematodes which are microscopically small worms, but they do see the consequences of infection and that is when the plantain or banana falls flat and they lose everything they have invested. In Ekiti State, south-western Nigeria, many farmers say that half of their plantain do not produce any bunch before the roots are destroyed. The hot water treatment is bringing back the lost glory of plantain in the area, thanks to IITA scientists. There is a huge market for plantain chips in Nigeria, and banana and plantain are major export crops in Cameroon.

 

Amongst the nematodes that destroy the root system of plantain and banana, one particular species is causing serious yield loss in several countries of sub-Saharan Africa. This species lives only in the root system of plantain and banana. For this reason, it is very likely that a farmer who digs out a sucker for a new field will carry the nematodes on the surface and in the roots of that sucker to a new field. “Nematodes are spreading very rapidly and they need the plantain or the banana as a host”, says Dr Stefan Hauser, an agronomist with the International Institute of Tropical Agriculture (IITA), who introduced the hot water treatment technology to farmers in Cameroon.

The good news is that nematodes can be controlled by placing the suckers in water at 52°C degrees for 20 minutes. Unfortunately this is where the problem occurs. Peasant farmers have no equipment to ensure the exact temperature. IITA’s scientists confirm that research demonstrates that the technology is effective, but outside research stations, it is difficult to apply.

To make use of the simple fact that heat kills nematodes and other pests and diseases but will not the sucker, Dr Hauser developed a simple and inexpensive method. Together with Cameroonian farmers, he placed infested suckers in boiling water for just 30 seconds. At this very high temperature (100°C) the heat shock kills all pests and diseases on and just under the surface sucker but does not kill a sucker. To boil water no special stove, container, and thermometer is needed to control the temperature. The only important thing is to not leave the sucker for too long in the boiling water. But farmers are resourceful: they just clapped their hands 30 times to mark the thirty seconds.

Nematodes could be eliminated by using broad spectrum pesticides of very high toxicity. Such pesticides, called nematicides, kill practically any organism. “They are expensive, they are pollutants, and I am not in favor of recommending them to farmers because these chemicals are systemic. The plants take them up and distribute them inside their tissue. One is never absolutely sure if there are no residues being retained in the edible matter”, says Dr Hauser.

The boiling water technology is simple to use, and cost-effective. “It may simply be a good idea to have this as a standard treatment against practically everything that is attached to the outer surface of the corm because it kills bacteria, fungi, nematodes, and weevils that pose a health problem,” says Hauser.

In the late 1980s, IITA scientists successfully developed improved plantain varieties that are resistant to Black sigatoka, a fungal disease of the leaves that caused tremendous yield losses to plantain in Africa. Last December, Dr Thomas Dubois, a bio-control specialist at IITA, won the CGIAR “Promising Young Scientist Award” for his work to create more durable banana in the Great Lakes region of eastern Africa, where the plant is the chief contributor to household income.  Dr Dubois developed enhanced tissue culture planting material–created from the banana’s cells.  The small banana plants are intentionally infected with a beneficial fungus which protects the banana against pests and diseases. Such plants have been delivered to farmers via an innovative public private partnership.

IITA’s scientists are also working on ways to make new varieties of plantain and banana as appealing to consumers as possible and to equal the flavor and texture of the traditional varieties. Postharvest specialists have developed new products, such as bread, wine, vinegar, soap, and industrial starch to add value to the crop. Meanwhile, IITA’s researchers have continued to promote the boiling water treatment to rid plantains and bananas of nematodes and other pests and diseases in sub-Saharan Africa.

 

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