It's always nice when you can clearly dump things into the good or bad box, and be done with it. I've always found the chemistry, politics, and economics of herbicides makes that difficult. They're by far the most widely used pesticide, are linked to serious health issues, and groundwater contamination. . Monsanto and Round-up could easily slip into the bad box: big corporation, synthetic chemical compound that gets a lot of press, got to be bad right? The problem is that most of the other herbicide compounds available to farmers are probably worse.
A field of one crop, with nothing else (ie. weeds) growing is very unnatural. But here's the thing, virtually every crop does go through a period where it needs protection from competition in order to be productive. But like the pristine lawn with no dandelions, there is usually a period when keeping the field "clean" has more to with pride than anything else. The options for farmers (and backyard gardeners) is to mechanically remove the weeds using your hands, hoes, or a variety of tractor implements that cut weeds and/or churn up the soil. This uses fuel, and sometimes (as most gardeners know) does little to stop certain types of weeds that are very hearty and persistent.(bind weed, quack grass, Canadian thistle, lambsquarters, mustard, etc. etc)
There are roughly 4 different types of herbicides. 2-4-D has been the most popular, and is found in all of the weed and feed formulations. That's because it's cheap to make, and is what's called a selective herbicide: kills the dandelions, but not the grass. It was created in the 1940's, and its chemistry is associated with other compounds with a far more controversial history: like agent orange, and 2-4-5T. The latter is now banned because dioxins were released during its manufacture.
Then there are the triazine family of herbicides, atrazine the most widely used. It works effectively with corn, but its drawback is that it doesn't breakdown very quickly and in the right conditions can easily contaminate groundwater.
There is paraquat (gained some notoriety when it was sprayed in Mexico to kill marijuana crops). It is quick acting and effectively kills everything it touches. If mishandled though, it can be very toxic to people. It can only be applied by licensed applicators, and was banned completely in Europe in 2007.
Then you've got the glyphosphates like Round-up, which relative to the other products in the herbicide toolbox, all of a sudden looks pretty good. Not as safe as Monsanto claimed it was. The New York attorney general ordered Monsanto to withdraw claims that it was "safer than table salt". Glyphosphates were first produced in the 1970's and prevent the production of a necessary enzyme in a plant, making it very effective. It's been particularly useful in so called no-till farming which means no plowing, and much less erosion and run-off. Round-up also breaks down quickly, and is not as dangerous to people as many other compounds. It does contain adjuvants or additives that have proven harmful.
As so often happens with pesticides, there is division within the scientific community on the danger of all of these herbicides. The bottom line for me is that RELATIVE to the other choices, Round-up appears somewhat safer.
What's upped the anti in the last decade is that Monsanto has also developed Round-up Ready crops, soybean, corn, cotton, etc that can tolerate Round-up, so farmers get to use a somewhat safer, but very effective herbicide, as little as one spray in a field, and have a productive harvest. But (here's the rub) Riound-up Ready crops have become so popular, that many weeds have developed resistance to it. And now 11 million acres in the United States have these so-called "super-weeds". I'd like to say that this was an "unintended consequence", but a lot of smart people warned against superweeds years ago. And scientists are worried: Glyphosate “is as important for reliable global food production as penicillin is for battling disease,” Stephen B. Powles, an Australian weed expert, wrote in a commentary in January.
Then there are these new concerns I touched on a couple of weeks ago:
This week another red flag came up that could have have enormous implications. Don Huber is a respected plant scientist, and a well-known opponent of GMO technologies and products. He's earned his opinions, and says he's found evidence of what he's calling microscopic pathogens in "Round-up ready" crops that he says are a huge threat to the health of livestock, plants and humans. It's the Round-up itself that he thinks is causing the problem, but obviously the development of Round-up ready crops using genetic engineering is what has lead to the huge spike, and widespread use of the herbicide.
There are some "organic" herbicides out there, usually the active ingredient is acetic acid (vinegar). I didn't have much success with it. I use my hands, a Japanese hoe, tiller, and I do spot spray Round-up on the most difficult and persistent weeds (when all else fails) and this is on a small acreage. If I had a hundred acres to take care of, I'd have to make a much harder decision.