Certain insects can be controlled by dusting the plants with wood ash. It is a method that can be used especially on smaller plots of vegetables, for example in the cultivation of okra, peppers and certain cucurbits.
Wood ash is particularly effective in controlling aphids. It is a simple, non-toxic method, which can be used free of cost by small-scale farmers. In addition to controlling the pest, it provides some mineral nutrients to the crop.
Dusting the ash should be done when the leaves of the crop are not too dry (the ash won’t stick) and not too humid (the ash will accumulate in water drops and cause damage to the leaves).
Wood ash is also sometimes used in the protection of stored products, for example to protect stored cowpea against bruchids (beetles belonging to the family Bruchidae).