FEATURE - Scientists fear invasion of \"superweeds\"
ROME - Beware the invasion of the superweeds.
Scientists fear genetically modified (GM) crops, already under attack for allegedly creating \"mutant\" food, could also create plants that are resistant to herbicides and insects.
These could germinate from a previous harvest, hampering weed controls.
GM herbicide-and insect-resistant crops are being planted on millions of acres (hectares) of arable land, mainly in North America, but some scientists worry about their impact on the environment.
\"There are several concerns about the consequences of development and deployment of transgenic herbicide-resistant and insect-resistant crops,\" the United Nations food body said in a paper on the risks and benefits of GM crops.
\"Objections to the use of these transgenic crops rest on several issues...such as: the potential transfer of genes from herbicide resistant crops to wild relatives, thus creating superweeds,\" the Food and Agriculture Organisation (FAO) said.
Media in Canada reported earlier this year that the country\'s expert panel on biotechnology said GM superweeds had invaded Canadian farms.
Canola plants engineered to help farmers had instead escaped and crossbred with each other to form plants stronger than their parents.
Most pesticides cannot kill these canola superweeds, which are growing in wheat fields where farmers don\'t want them.
Herbicide-and insect-resistant crops may pollute the gene pool of conventional relatives growing in the same area or nearby, depending on the wind and insects, the FAO says.
\"If there is no barrier to pollination, you get this potential hazard,\" Ricardo Labrada Romero, the FAO\'s weed and plant protection officer, told Reuters in an interview.
\"If, say, you are rotating maize with soybeans, you may find herbicide-resistant maize growing in a soybean field one year.\"
The development of superweeds increases the need for additional labour to weed by hand and rid fields of unwanted plants that compete with the food crop, reducing its yield.
\"Weeds compete with crops for water, nutrients and light and are responsible for up to five percent of crop losses in developed countries,\" Labrada Romero said.
The benefits of genetically modified crops are mainly economic as farmers need to use less herbicides or insecticides.
\"With herbicide-resistant crops, you use less tractors, less fuel and implements,\" Labrada Romero said.
James Dargie, a director of the FAO\'s agriculture department, told a recent seminar in Stockholm that use of GM crops in the United States had put the savings on weed control by U.S. farmers at $15 per acre (0.4 hectares).
\"One estimate puts the overall reduction in pesticide use within the United States at 1.2 million kg (2.646 million lbs) per year, suggesting significant environmental benefits,\" he said.
This month, the U.S. Environmental Protection Agency (EPA) approved for a further seven years the use of corn genetically modified with Bacillus thuringiensis (Bt), a naturally-occurring soil bacterium that produces a protein toxic to certain insects.
Incorporating the genetic material from Bt into corn plants enables them to produce the same toxin and defend against several species of pest.
The EPA rejected claims by some scientists that Bt harmed local Monarch butterfly populations.
\"The scientific evidence demonstrates that Bt corn does not impact Monarch butterfly populations,\" the agency said.
\"Bt corn has been evaluated thoroughly by EPA, and we are confident that it does not pose risks to human health or to the environment,\" it added.
\"Farmers can continue to use an effective, low-risk pest control alternative, which helps to protect the environment by reducing the amount of conventional pesticides used.\"
Story by David Brough
REUTERS NEWS SERVICE
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