On the one hand, this allows the farmer to use more herbicide. On the other hand, this leads to herbicide-resistant weeds. Genetic engineering will reduce the use of pesticides. Such crops produce the pesticide continuously in every cell. The net outcome of sowing pesticide-producing crops is an vast increase in pesticides.
Genetic engineering is environmentally friendly.
The increased quantities of herbicides and pesticides noted above is one strike against this claim. Pollen from genetically engineered crops can be transferred to cultivated and wild relatives over a mile away. This threatens the future of organic crops. It can pass herbicide resistance genes from GE crops to weedy relatives, necessitating the development of more herbicides. Also, the huge areas of genetically identical crops will influence the evolution of local pests and wildlife, and through the food chain, the whole ecology.