Wednesday, July 13, 2011

Herbicide resistance spreading

Studies show that herbicide resistance, and weeds, are spreading in the United States
Weed Science
July 12, 2011

Herbicide resistance is growing. At least 21 weed species have now developed resistance to glyphosate, a systemic herbicide that has been effectively used to kill weeds and can be found in many commercial products. Some weeds are now developing resistance to alternative herbicides being used. New occurrences of resistance are being noted in varying weed species and locations, creating challenges for weed scientists.

Several articles in the current issue of the journal Weed Science focus on the issue of herbicide resistance. The articles highlight first reports of resistance. “The herbicide resistance issue is becoming serious,” the journal’s editor, William K. Vencill, said. “It is spreading out beyond where weed scientists have seen it before.”

Palmer amaranth is a common weed that competes with cotton, soybean, corn, grain sorghum, and peanut crops in the southern United States. A density of 10 of these weeds per row of cotton has been shown to reduce yields more than 50 percent. By 2010, 52 counties in the state of Georgia had infestations of glyphosate-resistant Palmer amaranth.

Field and greenhouse tests conducted for the current study now confirm that this weed is resistant not only to glyphosate, but also to phrithiobac, an acetolactate synthase-inhibiting herbicide. This marks one of the first reports of multiple resistance to both glyphosate and pyrithiobac in Palmer amaranth. As multiple herbicide resistance becomes more common, a grower’s ability to be economically sustainable is threatened.

Another study in this issue conducted dose-response, ammonia accumulation, and enzyme activity tests on glyphosate-resistant Italian ryegrass populations taken from hazelnut orchards in Oregon. This research now confirms resistance of Italian ryegrass to another control alternative, glufosinate ammonium, a nonselective broad-spectrum herbicide.

In West Memphis, Ark., another study reports the first documented glyphosate-resistant johnsongrass biotype in the United States. A soybean field in continuous production over 6 years showed reduced control of johnsongrass with the recommended application rate of glyphosate. A greenhouse study was conducted with this johnsongrass to confirm this finding and determine any differences in absorption or translocation of the herbicide within these plants.

As herbicide resistance spreads, growers will need new weed management strategies. These could include herbicides with alternative sites of action within the plant or nonchemical methods such as tilling and mulching. Growers should prevent resistant weeds in a production field from reaching reproductive maturity to prevent spread of the trait through seed or pollen.

Tuesday, July 12, 2011

Flutters may be fewer

In midwest, flutters may be far fewer
By Andrew Pollack
New York Times
July 11, 2011

As recently as a decade ago, farms in the Midwest were commonly marred — at least as a farmer would view it — by unruly patches of milkweed amid the neat rows of emerging corn or soybeans.

Not anymore. Fields are now planted with genetically modified corn and soybeans resistant to the herbicide Roundup, allowing farmers to spray the chemical to eradicate weeds, including milkweed.

And while that sounds like good news for the farmers, a growing number of scientists fear it is imperiling the monarch butterfly, whose spectacular migrations make it one of the most beloved of insects — “the Bambi of the insect world,” as an entomologist once put it.

Monarchs lay their eggs on milkweed, and their larvae eat it. While the evidence is still preliminary and disputed, experts like Chip Taylor say the growing use of genetically modified crops is threatening the orange-and-black butterfly by depriving it of habitat.

“This milkweed has disappeared from at least 100 million acres of these row crops,” said Dr. Taylor, an insect ecologist at the University of Kansas and director of the research and conservation program Monarch Watch. “Your milkweed is virtually gone.”

The primary evidence that monarch populations are in decline comes from a new study showing a drop over the last 17 years of the area occupied by monarchs in central Mexico, where many of them spend the winter. The amount of land occupied by the monarchs is thought to be a proxy for their population size.

“This is the first time we have the data that we can analyze statistically that shows there’s a downward trend,” said Ernest H. Williams, a professor of biology at Hamilton College and an author of the study along with Dr. Taylor and others.

[Read More…]

Tuesday, June 28, 2011

GM wheat trials rejected

Scientists reject human trials of GM wheat
Belinda Tasker
Sydney Morning Herald
June 27, 2011

A group of prominent scientists and researchers from around the world has urged Australia not to go ahead with human trials of genetically modified (GM) wheat.

The CSIRO is carrying out a study of feeding GM wheat grown in the ACT to rats and pigs and could extend the trial to humans.

The modified wheat has been altered to lower its glycaemic index in an attempt to see if the grain could have health benefits such as improving blood glucose control and lowering cholesterol levels.

But eight scientists and academics from Britain, the US, India, Argentina and Australia believe not enough studies have been done on the effects of GM wheat on animals to warrant human trials.

The CSIRO has dismissed their concerns, insisting no decision has been made on if or when human trials will begin.

In a letter to the CSIRO’s chief executive Megan Clark, the scientists expressed their “unequivocal denunciation” of the experiments.

“The use of human subjects for these GM feeding experiments is completely unacceptable,” the letter said.

[Read More…]

Saturday, June 4, 2011

Gene alarm

Gene alarm on GM crops
The Telegraph
June 2, 2011

New Delhi - Indian scientists have discovered that the genetic modification of plants with a gene already used in crops worldwide may severely damage the plants, a surprising finding that may stir a debate on current crop biotechnology science.

The scientists at the University of Delhi have shown that inserting a bacterial gene that makes a protein named Cry1Ac into genomes of plants appears to cause developmental defects, growth retardation and sterility in the plants.

Several experimental and commercial genetically-modified plants, including GM cotton cultivated in India and other countries, make the Cry1Ac protein which is toxic to some insects. The insects die when they try to eat parts of these GM crops.

The Delhi scientists have now shown through laboratory experiments that modifying cotton or tobacco with Cry1Ac has a detrimental effect on these plants. Their results have appeared in the Journal of Bioscience published this month by the Indian Academy of Sciences.

“This is a completely unexpected finding,” said Durgadas Kasbekar, a senior biologist with the Centre for Cellular and Molecular Biology in Hyderabad who was not associated with the study, but is the editor of the Journal of Bioscience.

“Until this point, if you asked someone in the plant biotechnology community what the Cry1Ac toxin does in plants, they would say it kills insects. No one has yet demonstrated harm to plants as this study has done,” Kasbekar told The Telegraph.

[Read More…]

Saturday, May 21, 2011

GM Bt toxins in blood

Whole GM Bt toxins found in human and foetal blood
Press Release
GM Freeze
May 20, 2011

GM crops and imports must be halted

New research from Canada has found a Bt toxin produced by GM insect resistant crops in the blood of women and clear evidence that it was passed to foetuses.

Pesticides used on GM herbicide tolerant (HT) crops were also detected.

GM Freeze is calling for an immediate halt to GM Bt crop cultivation and imports of Bt GM food and feed until the findings are properly evaluated and further study confirms product safety.

The same Bt toxin as detected by the researchers is present in Mon810 maize, which has EU cultivation approval but is currently banned in France, Germany, Austria, Hungary, Luxemburg and Greece.

Regulators advise that no GM protein survives intact in the intestinal tract to enter the blood stream, so the detection of intact Cry1Ab toxin in human blood is of great significance.

The new study was carried out by a team at Sherbrooke University Hospital in Quebec and has been accepted for publication in the peer reviewed journal Reproductive Toxicology. The team took blood samples from 30 pregnant women prior to delivery, 30 samples from umbilical cords immediately after birth and samples from 39 non-pregnant women who were undergoing treatment. All the women were of a similar age and body mass index, and none worked with pesticides or lived with anyone who did.

The results show that the toxic Bt protein Cry1Ab was present in blood serum from all three sources (93% of pregnant women, 80% in umbilical blood and 67% of non-pregnant women). The researchers suggest that the most probable source of the toxin is GM food consumed as part of a normal diet in Canada, where GM presence in food is unlabelled. The Canadian scientists have not speculated on any health effects from the presence of Cry1Ab protein as this was beyond the scope of their study.

The findings add to concerns about the toxicity and potential allergenicty of Bt proteins expressed by many scientists.

[Read More…]

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