The Environmental Protection Agency (EPA) recently completed a required periodic review of glyphosate’s registration as a legal pesticide, and the product survived the process. Glyphosate remains legal and, according to the EPA, safe when used by the label guidelines. However, EPA is recommending a few adjustments to the label that some of its critics may appreciate. Since the National Deer Association (NDA) always urges our members and all deer habitat managers to use herbicides only when necessary and strictly by the label, we thought you’d like to learn about those changes.
It’s a given that some people will not be happy with this news or with this article. Whenever NDA mentions the word “glyphosate” in the context of deer habitat improvement or weed management in food plots, the anti-glyphosate squad shows up to inform us it’s Satan’s own brew. Glyphosate has become a controversial flashpoint and the focus of emotional rhetoric from people who seem fully invested in the idea that glyphosate is evil. But as with all aspects of deer biology, hunting, policy, and management, NDA bases our position on the preponderance of the scientific evidence. Just as science stands behind the label guidelines on all registered pesticides like glyphosate, it is also the basis of the EPA’s recent review. We will continue to recommend alternatives to herbicides, but where those alternatives are not practical or effective, we will continue to support the safe use of appropriate, registered herbicides by the label guidelines.
In April, the EPA released a 54-page “Proposed Interim Registration Review Decision” on glyphosate. I read it so you don’t have to, and I’ve shared the more significant take-aways below. However, if you’re more interested in this subject than the average deer hunter, I recommend you read the full report. We all have until July 5, 2019 to submit comments on the proposal before it moves forward to finalization. You can submit comments here.
About Human Health
After an exhaustive review of available international research, convening of expert panels, and a “thorough weight-of-the-evidence review,” the EPA continues to find that glyphosate is “not likely to be carcinogenic to humans,” nor did it identify non-cancer health concerns when glyphosate is used according to the label. I’m going to keep emphasizing this label thing, because that is the important factor in the safe use of all registered pesticides, including human and environmental health.
Many people now want to point to court cases and jury awards as proof that glyphosate should be boycotted or banned. Findings of juries are not science. The research that stands behind pesticide labels, and the reason those label guidelines are equal to federal law, is science.
None of this is to say I think glyphosate is good for you. The same is true as it always has been on the label: take the recommended precautions. Wear gloves and avoid getting it on your skin and in your eyes. Don’t spray when it’s windy or using nozzle settings that create a fine mist you are then likely to breathe. Much of what is known about glyphosate indicates it is among the least toxic pesticides you can work with, but you still want to put it on target weeds, not on or in you. If you’ve read the glyphosate label before, there are no surprises here.
Concerns for Other Species
Much of this new EPA report responds to concerns about the impact of glyphosate on pollinators such as bees and monarch butterflies, mammals, birds, and other non-target animals. You may find it interesting to read the EPA’s responses to specific consumer worries in the complete document, section C of the Introduction, pages 6-18.
New assessments did identify potential risks for mammals and birds. Where food plotters and deer habitat managers are concerned, the potential health risk or “level of concern” for mammals and birds feeding on plants treated with glyphosate was primarily for spot-treatment mix rates. However, these risk calculations assumed that entire acres were being treated at the high spot-treatment rates. This is not how “spot-treatment” works. More importantly, to quote from the report: “…the risk assessment assumes that birds and mammals will consume food items treated with glyphosate as 100% of their diet.”
This is like hearing that some everyday beverage you drink is toxic, but you must drink 5 gallons of it per day for a year to achieve the damaging effects. Deer don’t eat any single plant or other food source as 100% of their diet. Even where soybeans are abundant, for example, deer eat many other things in addition to soybeans.
NDA often points to alternative techniques for weed control. However, some weed infestations and invasive plant species simply won’t be brought under control with mechanical or manual removal or with fire.
Most of the time when I’m spot-spraying plants with glyphosate, they are plants deer never eat anyway, such as non-native thistle (as seen in the photo at the top) or invasive Japanese climbing fern. Or I’m treating the cut stump of Chinese privet or callery pear, in which case there’s no treated vegetation for deer to consume. Or when it’s necessary to use glyphosate to kill weeds before planting a food plot, it’s crabgrass, sicklepod or other noxious plants that, again, deer don’t eat. In fact, if deer ate these plants, I wouldn’t need to spray them.
However, sometimes we spray things deer will eat. Kudzu is a difficult-to-control invasive vine of the South that deer might eat before it dies after being treated. Glyphosate-resistant soybeans are obviously treated by a field application at an early growth stage, and they aren’t killed by it, so they remain available as a food item. The weight of the existing scientific evidence says deer won’t consume near enough glyphosate in this way to reach a level of concern. Nevertheless, you can always make the personal choice not to apply glyphosate to plants or crops deer will eat. That certainly leaves plenty of non-native invasive species you can control with glyphosate knowing deer are extremely unlikely to eat them before the plants die.
The other area of potential risk identified by the EPA in their review was spray-drift: glyphosate being carried by the wind away from target areas into bordering vegetation. The EPA admitted that pollinators, including bees and monarch butterflies, are harmed when important plants (like milkweed for monarchs) are killed by drifting glyphosate.
To address this, the EPA is proposing new language and guidelines on glyphosate’s label (which would make these practices required by law, as are any guidelines on a registered pesticide label). Most of the proposed changes address practices like crop-dusting, but some of them could affect food-plotters. The important ones to know about include:
Don’t spray when it’s windy. Specifically, this is referring to aerial applications, and the EPA specifies no more than 15 mph winds. But it just makes sense to avoid windy days with a ground application as well (hand-held, backpack, ATV or tractor sprayer) because your effectiveness may be reduced.
When using a sprayer with a boom attachment, the release height of the spray should be no more than 4 feet above the ground or crop canopy. Obviously, this is to prevent wind from redirecting the spray. It also just makes sense that you’d want the boom at the right height to ensure effectiveness of the herbicide.
Select a nozzle style and pressure setting that deliver “fine or coarser droplets.” If your nozzle and pressure combination result in a very fine mist, the spray is more likely to be carried away with a breeze before it contacts the target plant. There are literally six standard droplet classification categories from Very Fine to Extremely Coarse, and you should avoid Very Fine. To do this, NDA recommends the use of flat fan nozzles, and in our Deer Steward courses we go into detail on how to select the right nozzle for varying situations. But if the droplets are so fine you see a fog coming out of the end of your nozzle, you should know you need to adjust your sprayer or install different nozzles.
The EPA’s critics often claim the agency has studied only the active ingredient glyphosate without studying commercial products or “formulations” available on the market, in which glyphosate is often combined with inert ingredients intended to increase performance or effectiveness. According to the EPA, this isn’t true. All active and inert ingredients must be approved by the agency when individual products are registered. I won’t go into more details here, but if this is an area of concern for you, I recommend you read the EPA’s complete response to this claim. See “Comments on Formulations Toxicity” on page 10 in Section C of the Introduction.
In the broader world of agriculture and forestry beyond food plots, is glyphosate being over-applied or mis-used? Yes, and one confirmed result of over-reliance is glyphosate-resistant weeds, which NDA has warned against. But addressing worldwide mis-use of this herbicide goes beyond the scope of NDA’s mission. Where deer and deer hunters are concerned, glyphosate is safe for use by habitat managers when they follow the label.
Many deer habitat managers may still wish to minimize or avoid use of glyphosate and other herbicides, and we think that’s a laudable goal. Personally, I try to do this myself, and NDA often points to alternative techniques for weed control. However, some weed infestations and invasive plant species simply won’t be brought under control with mechanical or manual removal or with fire. NDA will continue to provide guidance on how to minimize or avoid herbicide use. We will continue to urge those who use them to follow the label instructions explicitly, as they are not only enforceable under federal law, they are intended to protect you and the environment from harm. And considering the new information from the EPA, NDA will continue to support the use of glyphosate when it is applied according to label instructions.