Introduction: Weeds cause greater reduction in potential yields than any other single factor by their competition for light, nutrient and water with the crop the farmer is trying to grow. This is particularly true at the small scale level where to tools available, such as the machete, are intended to be for multipurpose use rather than for weeding.
It is often traditional to start weeding when the weed canopy covers the whole area. At present most weeds are removed by mechanical means but the rate and type of work of the existing tools is both slow and tends to loosen the soil thus allowing valuable moisture to escape. In any one area weeds develop at the same time so the hand labour is limited to those who normally work on that area and where extra casual labour is available the cost is high in relation to the daily output. The net result is that some weeds are able to seed before they can be removed and the weed seed reservoir in the soil increases thus compounding the problem.