http://live.psu.edu/story/48259 Growing Roundup-Resistant Weed Problem Must be Deal with, expert says EDITED When Penn State weed scientist David Mortensen told members of the U.S. House Oversight Committee this summer that the government should restrict the use of herbicide-tolerant crops and impose a tax on biotech seeds to fund research and educational programs for farmers, it caused quite a stir. Mortensen, he professor of weed ecology in the College of Agricultural Sciences, has spent his career researching weeds that affect agricultural production, sustainable ways to control them, and the relationships between crops, native and invasive weeds, and pollinators. He has published several peer-reviewed papers on the subject in recent years. The resistant weeds cannot be killed by the sole use of glyphosate, the active ingredient in Roundup herbicide. The weeds now infest about 11 million acres -- a fivefold increase in three years, Mortensen reported. This list includes many of the most problematic weed species, such as common ragweed, horseweed, johnsongrass and several of the most common pigweeds -- many of which are geographically widespread. Mortensen expressed concern about herbicide- and germplasm-development companies responding to the glyphosate-resistance problem by developing a new generation of genetically engineered crops in which glyphosate-resistant cultivars are being engineered to have additional resistance traits introduced into the crop's genome. "These additional gene inserts will confer resistance to other herbicide active ingredients, including 2,4-D and dicamba," he said. "For a variety of reasons, it is quite likely that such crops will be widely adopted. Disturbingly, that would result in a significant increase of older, higher use-rate herbicides in soybean and cotton production. "If they are adopted in the way I expect they will be, herbicide use in soybean production would increase by an average of 70 percent in a relatively short time after the release of these new genetically engineered, herbicide-resistant cultivars." Vapor drift of more toxic herbicides has been implicated in many incidents of crop injury and may have additional impacts on natural vegetation interspersed in agricultural landscapes, Mortensen told lawmakers. Scientists have documented that nontarget terrestrial plant injury was 75 to 400 times higher for dicamba and 2,4-D, respectively, than for glyphosate. Together the herbicide and seed-breeding industries are moving to address the problem of resistance with crops that have been engineered to be resistant to multiple herbicide active ingredients, according to Mortensen. If these new crop introductions occur as reported, we should expect to see herbicide use continue to increase and a significant proportion of those added herbicides will be older, less environmentally benign compounds, he predicted. "Biotech companies are trying to deal with the problem by engineering new crop varieties that will be immune to more than one herbicide, but even those products will eventually run into resistance problems if farmers aren't careful," he said. "Transgene seed and associated herbicides should be taxed and proceeds used to fund and implement research and education aimed at advancing ecologically based integrated weed management," he concluded. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - To get off the CONS-SPST-BIOTECH-FORUM list, send any message to: [log in to unmask] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - To unsubscribe from the IOWA-TOPICS list, send any message to: [log in to unmask] Check out our Listserv Lists support site for more information: http://www.sierraclub.org/lists/faq.asp To view the Sierra Club List Terms & Conditions, see: http://www.sierraclub.org/lists/terms.asp