It has been found that many (like all grasses) have erect narrow leaves, with a leaf sheath providing space for pests to shelter and avoid direct contact with pesticides. Another interesting peculiarity of such crops is the minute hairs which actually repel water used for spraying pesticides to the extent of 90%. This results in ineffectual control, wastage of pesticides and eventually build up of resistance. This is a serious problem since replacement of generic pesticides with speciality products to do the same job raises the cost of production considerably.
Most pesticides companies approach the problem of pest resistance conventionally, by introducing a new molecule with a different mode of action. Often these pesticides, due to their very success in controlling a difficult pest become universally used. This very success mitigates against them and pests become resistant within a few years and we have to begin the cycle all over again. The tendency on the part of the farmer to apply excess nitrogenous fertilisers also enhances pest and disease infestation and consequently the spread of resistance. In crops other than paddy, the reliance on new varieties of seeds to replace existing varieties also comes at a cost which is against the long term interests of farmers.