BACK TO THE FUTURE: A chopping crew on a farm in Arkansas must resort to the age-old practice of hoeing to get rid of pigweed that has become resistant to glyphosate, the active ingredient in the herbicide Roundup.
Image: Brad Luttrell
In Brief
- Chemical herbicides keep nature at bay for only so long: weeds inevitably develop resistance to the chemicals.
- Indeed, weeds have begun to become resistant to glyphosate, the key ingredient in the widely used Roundup and a chemical that the biggest cash crops have been genetically engineered to withstand.
- Agricultural scientists must now seek out new strategies to protect plantings. Meanwhile some critics argue that reliance on genetic engineering should be reassessed.
In the second week of November, central Indiana is a patchwork of tawny and black: here a field covered with a stubble of dried corn and soybean plants; a little farther on, bare earth where the farmer has plowed under the residue of last summer’s crop. This is soil that wants to grow things, and already if you look closely you can see some shoots of fall weeds: chickweed, cressleaf and purple nettle. In a greenhouse on the campus of Purdue University, Chad Brabham, a soft-spoken grad student in weed science, selects two pots, each holding one 18-inch-high plant, bearing serrated, three-lobed leaves on a coarse stem. If the plants look familiar, you might have seen them growing in a vacant lot or by a roadside almost anywhere in the lower 48 states. They are Ambrosia trifida, or giant ragweed—a plant as ugly as its name and as useless, well, as its cousin, common ragweed, A. artemisiifolia, a machine for sucking up water and spewing out highly allergenic pollen. If the farmers stopped farming, it would not take more than a few years before this part of Indiana would live up to the nickname that agronomists joke should appear on its license plates: Giant Ragweed National Forest.
Over the past half a century or so, that fate has been kept at bay primarily by chemical herbicides. One of the most widely used is glyphosate, best known as the active ingredient in Monsanto’s Roundup weed killers, among others. Brabham positions the two pots in a spray chamber and fills a small tank with a solution of the potassium salt of glyphosate. A traveling spray head swiftly traverses the length of the chamber and soaks the drab-green leaves with what by all rights should be a lethal dose. Brabham removes the pots and returns them to the growing table. What happens to these weeds in the next 24 hours will show, in microcosm, what farmers will face across the Midwest this growing season.
This article was originally published with the title The Growing Menace from Superweeds.
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9 Comments
Add CommentAn article about a dire threat to the ability of the USA to feed itself and the only 2 comments are spam advertisments from users that I have reported many times over the last couple of months. How sad that SciAm is so incompetent that they can't even remove accounts that exist for the sole purpose of spamming. I'm so pissed off that I forgot what comment I had on the super weeds.
Reply | Report Abuse | Link to thisOverenthusiasm for GMOs to enrich a few companies is causing other problems too, perhaps the worst is eroding biodiversity of our traditional cultivars, another is eroding the economics of our neighbors to the south by flooding them with GMO corn so they cannot subsist on their small maize farms and have to migrate north in a flood. Nice return for giving us the favor of developing corn, tomatoes, potatoes, tobacco, manioc, guavas, papayas, etc.! Companies that get rich on these should pay them royalties, not the other way round! That would be "liberty and justice for all."
Reply | Report Abuse | Link to thisI remember in my youth many summer hours walking beans,the only source of income for many youths my age until all these herbicides came along.Now many adults will find employment doing this task as well,and whats so bad about that?
Reply | Report Abuse | Link to thisThe characterization of Ragweed and Pigweed (Amaranth) as monsters is plain silly. These plants are just doing their amazing thing…surviving. Ragweed for one (and I am allergic) is a wonderful survivor and great colonizer of bare ground. Linnaeus wasn’t kidding when he chose the name Ambrosia--its nutritious achene provides lots of calories to wildlife. So does Amaranth (which is a human food staple,as well).We have known about chemical resistance since about five minutes after we started using chemicals to kill pests. (Thank you, genetic diversity!) Yet we are using the same chemicals in ever greater quantities. I say, Go Weeds!
Reply | Report Abuse | Link to thisTo quote the Genesis song about the giant hogweed "They are invincible"
Reply | Report Abuse | Link to thisI have to agree. I have always faulted herbicides for at least a little bit of our unemployment rate.
Reply | Report Abuse | Link to thisMaybe it's time to go back to smaller farm operations and natural farming methods. Work with nature rather than try to beat it.
Reply | Report Abuse | Link to thisI hear clover is good for the soil and bees. Encourage that. If farmers are more careful and plow the ragweed etc under before it seeds when fields are left to fallow, as much as possible, instead of relying on chemicals the plants just get used to- and the problem should be more manageable. No?
Reply | Report Abuse | Link to thisLet's see: call an native staple, amaranth, a superweed. Douse a large portion of the US with a general broad spectrum herbicide. Make testing effects of this herbicide illegal (licensing). Do this to grow GMO crops. Note that it is also illegal (licensing) to test GMO's for effects. Realze these crop are patented by one of the worlds worst polluters Mon$anto:
Reply | Report Abuse | Link to thissaccharin USDA attempted ban 1972
PCBs 1929 banned 1979
Agent Orange (2,4,5-T + 2,4-D) 1943 banned 1979
DDT 1944 banned 1972
dioxin 1962-1971 banned 1977
aspartame 1985
bovine growth hormone 1994 banned 2000 EU,CA,AU,NZ,JP
nuclear weapons 1947 banned 1996 (S.T.A.R.T.)
polyurethanes 1954
GMO 1982 banned in EU, JP,
Flavr Savr tomato 1996
terminator gene 1990
56 contaminated sites (Superfund sites)
Then, discuss (in the magazine article) how bad GMO-bent-grass could be -- knowing Round-up Ready bent-grass(horizontal gene transfer?, natural selection?) is already a problem in eastern Oregon -- without mentioning the next and just USDA permitted superweed, the perennial GMORRAA (GMO Round-Up Ready Alfalfa).
And then ask how we are going to feed the world in the future. Oh, of course the magazine told us: with the herbicides 2,5,4-T + 2,4-D (would that include Dioxin as before)? Will it still be called Agent Orange?
"You shall not pollute the land in which you live... you shall not defile the land in which you live, in which I also dwell." Numbers 35:33-34
GMOs encourage the dousing of the environment with toxins that accumulate in the plants they are protecting; nor do they increase per/ac production according to latest UN studies. They do however increase purchase of agro-chemi-TOXINS and impoverish farmers. That is their sole value to Mon$anto. GMO-addiction is no better than smoking tobacco, and the tactics are the same.