Chief among the precepts in the organic foods movement is a condemnation of synthetic pesticides in crops. Thus, "natural" means of controlling insects and pests of agriculturally important plants are very important. The bacterium Bacillus thuringensis produces a protein interferes with the digestive system of most insects, but doesn't affect other animals. Behold, a "natural" solution.
Plants can then be sprayed with B. thuringensis to reduce an infestation, and the crop can still be considered "organic". Then, scientists introduced the gene that makes the Bt protein directly into corn and other crops, effectively obviating the need to spray the plant at all - but because it used a transgenic technology, it loses the cachet of the organic label.
Ironic, isn't it.