cudspan's picture
About regulation... Another answer by Steve Savage says the following -- "The USDA considers whether there are any “plant pest” issues with the specific crop and trait such as the ability to cross with weedy relatives." and "The EPA gets involved if there is anything pesticide-related to do with the trait such as tolerance to a herbicide". Ok, so we now have proof that Roundup Ready cotton has crossed with Pig Weed, and according to a NY Times article Monsanto is actually funding the use of highly toxic herbicides to eradicate this super weed. So doesn't this mean that Roundup Ready products must be reviewed again, and possibly pulled from the market?

A:Expert Answer

No, this is not an example of a biotech crop crossing with a weed. The “pig weed” in question here is actually what is known as Palmer Amaranth―a serious weed problem in its own right, regardless of herbicide tolerance. As with many other weeds that have become resistant to herbicides, including those long before biotechnology, it is not an issue of the tolerance moving to the weed by outcrossing, but rather that the use of the herbicide selects for resistant types that occur within the natural genetic diversity of the weed population. If anything, the issue has been that farmers have relied too heavily on Roundup and, in the case of this weed, have used it at lower rates that facilitated the adaptation of the resistant types over time. The best way to control weeds without selecting for resistance is to use different approaches over time to minimize that selection pressure. As for what herbicides are used to control the resistant types, they are not “highly toxic” in the sense that people imagine. They are toxic to the weed but generally not to animals, insects, etc. Weed control is, and always has been, a major challenge for farmers. Doing it with mechanical tillage mechanisms is problematic for the environment (erosion, loss of soil organic matter, high fuel consumption…). Herbicides, carefully and strategically used, are the best option.


Zbeeswax's picture

I am currently doing a test on a small piece of barren and compacted land, the goal being to remediate the damage. I dug small pits, spread a thin layer of straw mulch and seeded it with Buckwheat, Alfalfa, and Ladino White Clover. The idea was to increase water retention and stimulate pedoturbation through the action of plant roots, ants, termites etc... and to establish a vegetative cover. So far germination of the seeded species has been sparse though not insignificant. However, after spreading the mulch a large number of Pigweed seedlings emerged from the seedbank (Amaranthus retroflexus and Amaranthus spp one I couldn't identify past the genus). Around these Pigweeds, which are thriving, the water retention of the soil is greatly increased and the soil has become noticeably looser.
My point in sharing this is that Pigweed has value. It seems to me from these limited observations that it plays a role as a pioneer species on compacted land. Seeing as compaction is a serious problem on land under large-scale mechanized agriculture this seems to be no small thing.
Instead of seeing the Pigweed and identifying them as an obstacle to the short-term goals of the farming operation, a perspective that is shortsighted considering agriculture is dependent upon the natural processes of soil-formation, it might be better to ask why has the Pigweed grown in the field to begin with.
Since Pigweeds have several very close relatives that are economically viable crops, it begs the question, why aren't tests being run on these as part of a crop rotation to ameliorate problems of compaction?

cudspan's picture

Fair enough -- it wasn't crossed with the Roundup Ready trait. And so it's not a trigger for regulation. But you introduce another problem -- the purpose of a Roundup Ready crop is to rely exclusively on the herbicide, or as nearly exclusively as possible. Yet you say that exclusive reliance on an herbicide is what yields resistant weeds. So in either event the result seems inevitable... An agricultural paradigm that by definition spirals away from sustainable practices.

I also find your claim that the other herbicides are not "highly toxic" is tricky. The selling point for Roundup is that it reduces the overall use of herbicides. I distinctly recall hearing or reading claims that Roundup is less toxic. I tried to find anything on the Monsanto site that mentions Roundup being less toxic than other herbicides, but perhaps to their credit it seems they don't sing that tune. In fact, I can't seem to find anything on the web that talks about the comparative safety of Roundup!

NeedsTheTruth's picture

most of the usda is composed of monsanto eployees....

Alex Huszagh's picture

I think you'd find this post on the relative toxicities of pesticides and their presence on produce interesting:

It is another piece written by Steve Savage.

Community Manager's picture

@Alex Huszagh – Thanks for sharing! Yes, a great post from Steve which further explores this topic.

Thanks for your comment @cudspan, you may be interested in this post which explores how herbicides can play a role in weed management and links to the Weed Science Society of America’s best management practices

@NeedsTheTruth – please remember to post constructive comments which focus on the facts included in the provided answer. An expert is currently reviewing a similar question on this topic, please stay tuned for a response.