They only use Bt sprays in emergencies. The combination of maintaining a balanced relationship between pests and plants, and drastically limiting the amount of Bt released into the environment in any given time period, slows, or even eliminates, the probability of resistance. Consequently genetic engineering will, in a few years, destroy a tool that organic farmers have used effectively for decades. It is ironic that transgenic crops are being introduced to reduce chemical pesticide use when it is taking away one of the rare pest control tools that farmers now use to avoid synthetic chemicals. While it is heartening to see that companies developing Bt transgenic plants recognize that resistance will be a problem, their proposals for reducing resistance with unique field management recommendations are ineffectual.
Most farmers operate under very intense financial constraints.
Consequently they make field management decisions based on immediate financial returns, not future problems. They are too preoccupied with today's doom to worry much about tomorrow's doom. In the early 1980's, for example, farmers in North Dakota were warned by everyone from extension agents to seed sales people, that failing to rotate sunflowers would invite sunflower insect and disease disasters. But sunflowers were a good cash crop that produced much needed revenue, so most farmers raised sunflowers in the same fields at least every other year, and in some instances they continuous cropped them. Within a few years insect and disease problems became so severe that the cost of pest control forced many farmers to get out of sunflower production.