Herbicide resistance arises in an analogous fashion to the emergence of antibiotic resistance in bacteria. Mutations occur in plants and when one arises which makes it resistant to the herbicide, it will have an advantage and grow and flourish when other plants are killed Resistance to glyphosate is easy to induce in plants in the laboratory. Monsanto claims resistance to glyphosate is unlikely to emerge in the field because it does not persist in soil. However, weed resistance to paraquat, an herbicide which has a shorter soil persistence than glyphosate, is already a serious problem. Even before the increased use of glyphosate expected with the introduction of resistant crops, there has already been a report of glyphosate resistance in a weed which occurred in ryegrass in Australia.
Gene flow is possible in the Far East where soybean originated and wild related plants exist.
Herbicide resistant volunteers may be a problem where mild climates occur and overwintering of soybean is possible. Herbicide resistant crops are an expensive problem for farmers. Thus herbicide resistant soybeans promise increased herbicide use and associated damage to the environment, together with an increased risk of weed resistance, which would be a costly problem for farmers. Pesticide News 33 pp28-29, September 1996. Water Soil and Air Pollution .