Pesticide resistance has for long been a farmer’s worst nightmare. Its management, especially in high value export crops has been difficult partly owing to the high standards required and the limited number of market acceptable pesticides.
But it no longer needs to be the stuff that nightmares are made of. With an understanding of the factors that promote its development, any farmer can stop pests from taking over his farm and watering down his investment. Consequently, Kenya’s produce won’t be the subject of some stringent restrictions in the European market where it exports most of it.
The development of resistance being almost a given where pesticides are used regularly, it is nowadays recommended that farmers should start resistance management from the beginning. That way, they minimize the chances of its occurrence and save on money as well.
Before venturing into the productions of a crop, experts recommend that they should use information from manufacturers and Integrated Pest Management (IPM) specialists.
The two are invaluable sources of information on baseline susceptibilities, can define probable resistance problems beforehand to help the prospective farmer from being found flat-footed and are also helpful in coming up with proper pesticide use strategies.
Alternatively, the grower can extract such information during product launches and by having discussions with fellow growers. There are three broad strategies of managing resistance; namely, moderation, rotations and mixtures and saturation.
Moderation which is basically limiting the use of a pesticide should be the first step. When a farmer decides to engage in moderation he or she should employ it in concert with IPM practices. Experts advise that moderation should be used to the fullest extent that will provide commercially acceptable control.
On other hand if he favours the rotations and mixtures strategy, which works on the premise that an individual pest is less likely to be resistant to two or more differing classes of pesticides, it is advisable to bear in mind the cost of pesticides. However, typically mixtures of insecticides and miticides have performed poorly. The last strategy, saturation, the use of pesticides at higher rates is recommended as a last resort. Even though it provides control for a time by increasing selection pressure on the pest, it comes at a greater cost.
Therefore the need to develop resistance management programs (RMP) is critical in resistance management. The program describes the tactics or measures that should be taken to manage pesticide resistance for a specific pest. The objective is to reduce the selection of resistance genes in a pest population.
In coming up with a programme, IPM should be part of the management. Resistance prevention and management programmes when new pesticides are introduced should also be implemented. Additionally, a grower ought to consider alternative (non-chemical) pest management measures while also using more than one class of pesticide. The evaluation and refinement of the RPM should be continuous.