Michael Ottman, 1140 E South Campus Dr., University of Arizona, University of Arizona, Dept. Plant Science, Tucson, AZ 85721
Transgenic crops have changed farming systems in the Western US. The principal transgenic crops in this region are corn grown in all western states, and cotton grown in Arizona, California, and New Mexico. Soybeans are not grown in the West, and acreage of transgenic canola, wheat, and alfalfa are limited. The Roundup Ready trait in corn and cotton has reduced the need for in-season cultivation and allowed conservation tillage systems to develop. Conservation tillage reduces the turnaround time between crops and has facilitated multiple cropping of corn silage in warmer areas. The BT trait has been a very effective tool for pest management in cotton and corn. Insecticide applications have been drastically reduced in these crops and permitted more flexibility in crop rotations. Continuous cropping is not as limited by insects controlled by BT, and rotation to other crops such as tomato that have pests in common (eg. corn ear worm and tomato fruit worm) is not as restrictive.