On-station trials

The objective of the project was to provide control methods against the bruchids which will allow farmers to store cowpea over the dry season without fear of losses. The requirements were that the control methods would be effective against the pest, and likely to be adopted by farmers: affordable, safe and culturally acceptable.

Potential control methods were selected:

Trials undertaken on-station, in northern Ghana, tested the effectiveness of the selected methods, traditional and modern alternatives (no synthetic chemicals):

The following charts present some of the results of the on-station trials:

% damage in cowpea after six months storage

Treatments with ash did not prove effective, but treatments based on shea nut butter did.

'Solar disinfestation' was developed by the CRSP project. This control method uses the heat of the sun, increased by a greenhouse effect, to kill the bruchids. Their laboratory research has shown that exposure to temperatures of at least 57.3 degrees centigrade, for 1 hour, kills all stages of the pest. The drawback of the method is its cost, which makes it unlikely to be adopted by small scale farmers.

The original method was modified to reduce its cost (by half), making use of materials available to farmers at no extra-cost. Solarisation experiments demonstrated that the modified method would be effective, as shown by the temperatures recorded during the trials:

Chart showing temperatures attained during solarisation