In recent years, there has been a lot of press about the chemical glyphosate. Specifically, there have been some high-profile court cases where companies manufacturing and using the chemical have had to pay out large sums of cash to workers who were later diagnosed with lymphoma. This has resulted in a lot of people questioning the safety of the chemical and even calls to legally ban its use (which has gone through in some places).
First off, I think it is important to separate glyphosate from Monsanto. Monsanto as a company has definitely engaged in some shady business practices that need to be addressed. However, while they are one of the leading producers of glyphosate they are not the only ones. Different products of glyphosate are formulated differently with different chemicals added to them. Two different products can behave radically differently. Even concentrates like I normally use are only 40%-50% glyphosate and ready-to-use products are sometimes as low as 1%. There is a lot of other stuff in the bottle that affects how the chemical behaves.
I agree with the general concept of reducing the use of chemical control in general and finding safer alternatives. However, in some cases, there simply isn’t an alternative or the alternatives prove much more dangerous. To help people who are unfamiliar with the field of pest control understand, I’d like to take a minute to explain Integrated Pest Management (IPM).
Under an IPM plan, a variety of different methods of pest control are implemented. The idea is that no one method is perfect and will always miss some of the pests, but by combining different methods they will have a synergistic effect. This causes a greater total effectiveness at the same cost of time and resources. It also helps reduce the negative side effects of any one control method.
As an example, on a site I am managing at the moment we are using a combination of chemical, mechanical, manual, and biological control. The latter three are effective, but there are issues preventing them from completely taking over for the chemical control.
We are trying to get a native forest ecology established in place of the invasive plants, so mechanical control (mowing) can only be limited. We don’t want to mow areas that we are starting to successfully have trees grow into. Killing the desirable saplings puts us back to square one. It might even be worse because mowing actually benefits some of the invasive plants present.
Manual control (hand pulling, hand cutting, etc.) might be more delicate around desirable plants, but there is an issue of scale. We have hundreds of acres to cover and it is prohibitively expensive to run the needed manpower through the site to do that. If I was given an unlimited budget, I would love to just have an army of laborers take over. However, no one is willing to pay for that. On a smaller project, I could probably make it happen, but not on something like this. There’s simply no one willing to pay that much money for invasive plant control.
Biological control is very limited. We are introducing a species of weevil that loves to eat Mile-a-Minute (an invasive vine) but they don’t eat anything else. Walking goats through the site might work for some parts, but it really just replaces mowing more than chemical control. They will also sometimes get picky about what they eat and will sometimes save the species I want them focusing on (thistle and rose) for last because of how prickly they are.
We aren’t using burning but we have considered it as an option. The problem is that we have a very narrow area that we are trying to hit and we have residential areas and crop fields bordering the site in some places. Not the kind of places you want notoriously difficult to control fire escaping to. There is also the fact that some of the invasive plants benefit from fire more than any of the native plants would.
What does work to fill the gaps is chemical control. If we have a chemical that we can precisely use to target specific plants, that enables us to focus it on just the invasive species. Chemicals that are engineered to affect only specific groups of plants would be great in theory, but the problem is that we have a wide variety of native plants and a wide variety of invasive plants. Any chemical which would affect any of our invasives will also affect at least some of the native plants we are trying to get established.
The other option is to pick a chemical that is absorbed by the leaves but not by the roots. This allows us to target our spray and spray only the plants we want to kill while sparing the plants next to it. It would need to be a non-selective herbicide due to the wide variety of target species. It would also need to be systematic because many of the plants can survive defoliation and regrow from the roots. Instead, we want the chemical to be absorbed down to the roots to kill the plant as a whole. Finally, it needs to be non-toxic to fish and amphibians in application concentrations because of the close proximity to streams and wetlands.
Glyphosate meets all of those requirements. For some plants, we have switched to triclopyr amine since it also meets most of the requirements. However, it doesn’t work on grasses or many herbaceous plants. It also comes with an increased risk to the applicator since there is an increased risk of eye damage if an accident occurs where someone gets it in their eye.
There are grass-specific herbicides that could be used to supplement the triclopyr, but they are generally not approved for use in wetlands. The ones that are come with an even higher health risk to the applicator than the triclopyr does. As one of the people who would be in the field using it, I feel more comfortable with the glyphosate being sprayed near me than with those chemicals.
We also have a rather unique species to deal with. Japanese Hops is not a common invasive species (yet) so there aren’t many sources discussing how to control it. However, it is a major problem on my site and it forms one of the primary targets that I am trying to control. Research has shown only limited effectiveness of most chemicals. Specifically, typical broadleaf specific herbicides (hops is a broadleaf plant) like triclopyr and 2,4-D seem relatively ineffective.
There is one chemical that was distinctly more effective than glyphosate, but that returns us to a different problem. That chemical is noted as being extremely toxic to fish. Not only is it not approved for use in wetlands, it specifically calls for a vegetated buffer between the spray area and any waterways. Since that vegetated buffer is exactly where I am spraying while trying to get a riparian forest established, that chemical isn’t an option.
The result is that glyphosate is the most effective and safest chemical for me to use. Yes, it is still a toxic chemical and I need to be careful with it. It is, after all, a poison designed to kill things so it would be surprising if it was no danger at all to humans.
That brings me to a different topic. All pesticides (at least in the US) are required to be inspected by the EPA and come with detailed instructions on how to use them safely. It specifically calls out cleaning procedures and what Personal Protective Equipment (PPE) much be worn. This was not always the case. Many of the court cases on glyphosate originate from accidents that occurred before this labeling process was the standard. Workers were told it was perfectly safe and so didn’t bother rinsing themselves after having concentrate spilled on them. Warnings on the containers are much more detailed now and by law, all workers take much more thorough precautions than they used to (my crew goes beyond the minimum required by law).
So, it may be true that when the plaintiffs in those court cases were working the manufacturers and their employers were not taking appropriate precautions with the material. A failure to inform applicators of the dangers of the chemical would certainly put them at fault. In the present time, however, applicators are taking much more thorough precautions. Additional safety measures have already been implemented and a complete ban on the chemical would be an overzealous approach that would cause more harm than good. I can certainly say that personally, I take more precautions with glyphosate than I did with more dangerous chemicals I’ve handled in the past.