   Genetically Modified Crops: Are They Safe? - January 17, 2001 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County I promise to get back to planting, pruning, fertilizing, etc. soon. Since, it's still winter, you can continue dreaming of seed catalogs and copious harvests to come. Beside that, last week I was on a roll and I wanted to follow up that column (genetically modified crops) with some additional information, thoughts, and considerations about their safety to the environment. As with any new technology, we must consider both potential benefits and risks. In the case of genetically modified crops (GMO crops), potential benefits are: increased crop yield, increased efficiency during production, reduce inputs of pesticides, reduced soil erosion, and even their ability to efficiently remove toxins from polluted soils. Conversely, potential risks include: invasiveness, negative effects on native, non-target organisms, and complex effects that cannot be predicted because of unforeseen interactions. The benefits are most often publicized by the producers/marketers of the GMO crops. Last week, I discussed Bt corn: the introduction of a Bacterial protein into corn plants to give them natural resistance to caterpillar attacks. This technology is also being used in cotton being grown in Arizona. Another GMO tactic is to introduce herbicide resistance into the crop. This allows weeds to be sprayed with herbicides without doing harm to the crop plant. The result is lower inputs of labor and increased crop yields due to decreased competition from weeds. These two technologies have been widely publicized, but there are others such as slower growing turf grasses that will have reduced water, fertilizer, and mowing demands. The following data support these benefits. In 1998, 8.2 million fewer pounds of active pesticide ingredient (3.5%) were used on corn, cotton, and soybeans than in 1997. This corresponded to an increase in the use of these GMO crops. Reduced pesticide use was not noted in glyphosate-resistant (herbicide-resistant) soybeans. Here, glyphosate use increased, but other herbicides decreased in use. The risks are also publicized in the media. The biggest question is: will these GMO crops escape the fields and invade the countryside transferring their genetic modifications into native populations? In reality, few agricultural crops have become invasive. Another consideration, if the plant itself does not "jump the fence", will its genes somehow escape the host plant and invade adjacent native plant populations. There is evidence that crop plants can hybridize with closely related species or subspecies under laboratory conditions. This could potentially allow introduction of GMO genes into non-crop plants. No experiments have been published about the possibility of this occurring in natural populations. However, past experience suggests that accidental introduction of GMO genes is a possibility. For seven species (wheat, rice, soybean, sorghum, millet, beans, and sunflower seeds) of the world's top 13 crops, hybridization with wild relatives has contributed to the evolution of some weed species. Other concerns about GMO crop risks are numerous. Many require a strong biology/biochemistry background to understand. To give you some ideas, consider how GMO crop residues alter populations of soil organisms or the chance that a virus could "steal" the GMO gene and transfer it to biologically unrelated organisms. The ultimate question: do the benefits outweigh the risks? There is no way to do this topic justice in a brief newspaper column, but I have tried to present the information in an unbiased manner. I challenge all readers to follow this topic and inform yourselves. The information presented in this column came from a December 15, 2000 article in science magazine (Wolfenbarger, L.L. and P.R. Phifer. 2000. The Ecological Risks and Benefits of Genetically Engineered Plants. Science. 290:2088-2093). The University of Arizona Cooperative Extension has publications and information on horticulture, natural resources, animal science, family consumer science, and 4-H youth development. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@kachina.net and be sure to include your address and phone number. The Yavapai County Cooperative Extension web site is http://ag.arizona.edu/yavapai/. |