Most environmentalists do not consider genetic engineering a green technique. But Donald Weeks, professor of biochemistry at the University of Nebraska in Lincoln, begs to differ.

"It's a real shame that people have been given false information regarding biotech crops," Weeks told BioWorld Today. "Biotech crops have gone a long way to help" with sustainable farming practices.

In the May 25, 2007 issue of Science, Weeks and his colleagues described a new biotech crop that they hope will fit the bill: crops that have been genetically engineered to be resistant to the herbicide Dicamba.

Dicamba, Weeks and his team wrote in their paper, is "a widely used, low-cost, environmentally friendly herbicide that does not persist in soils and shows little or no toxicity to wildlife and humans." The researchers engineered an enzyme from a soil bacterium into tomato and tobacco plants, as well as the model plant arabidopsis.

The enzyme is able to break down Dicamba, preventing its buildup to toxic levels. They found that the engineered plants were able to withstand the levels of Dicamba that farmers use to kill weeds prior to planting.

Weeks said that an advantage of the herbicide-resistant crops is that planting them can happen during or shortly after spraying for weeds, which lengthens the growing season. Without such resistance, farmers have to wait for several weeks after spraying - or use tilling, which leads to severe erosion, to control weeds.

The use of Roundup Ready plants, which have an enzyme engineered into them that is not affected by Monsanto's Roundup herbicide, has enabled the use of conservation tilling by the same principle. But Roundup-resistant weeds are emerging in some areas of the country.

Weeks said that such resistance is not due to lateral gene transfer, but to old-fashioned natural selection of weeds that are resistant in their own right. He said that by combining or alternating the use of Roundup- and Dicamba-resistant crops, the more widespread emergence of resistant weeds could be prevented or at least delayed. "We really see Dicamba complementing Roundup quite nicely," he said.

Weeks also believes that the resistant crop plants will enable the use of low levels of Dicamba overall because "most broadleaf weeds are highly susceptible to treatment with Dicamba." Lower use has been observed for insecticides when farmers plant crops engineered to contain the Bt toxin from yet another bacterium, Bacillus thuringiensis, that targets many insect crop pests.

Weeks said that especially in developing nations, decreased insecticide use is important for farmer's health as well as environmental reasons. "Cotton has traditionally been the most heavily sprayed crop," he said, but where Bt crops have been planted, the number of sprayings with insecticides has decreased from around 10 down to zero to two. That is true in the U.S., but also, and perhaps more importantly from an environmental and health perspective, in developing nations such as China and parts of India.

"Those people are poor farmers, and their methods of application are rather limited - usually direct hand spraying with no protective masks, clothing or gloves," Weeks said. If there are fewer sprayings, "That's good for people, and that's good for the environment."