What would Jeff Gillman do? Roundup and my garden

When I was first approached about having Jeff Gillman, author of The Truth About Organic Gardening, write a post for my blog, I several ideas that I presented to Jeff. He was willing tackle all of them! I decided to relate how I have used Roundup in my garden, and let Jeff comment on my practices, for the education of us all. Here goes…

I have many kinds of invasive plants growing on our acreage. I also have many types of trees and shrubs growing here which, while not invasive (indeed, many are native), are weeds when growing in my cultivated garden. In the course of reading Sara Stein’s Planting Noah’s Garden: Further Adventures in Backyard Ecology (1997), I became persuaded that Roundup, used as she described, was a responsible way to take care of these problems. Below are some excerpts from the chapter on controlling weeds that indicate what types of points she made.

Jeff: I tend to agree that Roundup is useful in these sorts of situation. And by Round-up I mean glyphosate (that’s the primary active ingredient in Round-up) without any extra bells and whistles (all kinds of other active ingredients may be added – I don’t like them because they make the spray more toxic and may make the glyphosate itself work better – or worse).

“Cutting down a [woody] plant is the physiological equivalent of pruning it to encourage new growth . . . To finally kill the plant, the sprouts have to be cut repeatedly until the roots are depleted of stored nutrients and the plant starves.”

“Glyphosate adheres to soil particles, so it does not enter groundwater. Soil microorganisms rapidly break it down to phosphate, a plant nutrient . . . and glycine, an amino acid that . . . is further broken down into nitrogen, carbon dioxide, and water.”

“Glyphosate is a nonspecific herbicide: it kills every kind of vegetation. For this reason, and despite its low toxicity to animals, it should be used only in the most precise manner to avoid injuring any but the target species.”

Jeff: Basically true – but it can be pretty darn toxic to aquatic animals such as frogs – not the glyphosate itself mind you, but rather the things it’s mixed with such as soaps.

“Roundup . . . [is] sold in both diluted and concentrated form. Choose the concentrate; it can be diluted in water to the percentage most effective for the control method you’re using.”

“In most cases, invasive trees and shrubs can be killed by brushing a small amount of herbicide onto the freshly cut surface of the stem or trunk. This method, called cut-surface application, uses the least possible chemical and delivers it precisely to the target plant.
* The chemical must be applied to a fresh wound . . .
* Treatment is most effective toward the end of summer . . .
* Use a concentrated solution . . . Those experienced in cut-surface application have found a 20% solution (1 part concentrate to 4 parts water) sufficient for most species. You need only a very small amount: 1 cup (8 ounces) is enough for a weekend’s work.
* Prevent spills by keeping the mixture in a jar with a screw top that you can close when you’re not using it. A rubber cement jar, sold in art stores, makes an excellent container. The screw top has a brush that’s adjustable in height so the bristles are moistened but not dripping.”

Jeff: This is a way that glyphosate is often used and it is quite effective. But once again, be careful to use glyphosate without the extra active ingredients.

Our property was neglected for several years before we took ownership, and there are some maple saplings growing in lilac thickets that kept resprouting after I cut them to the ground. We have a large patch of Japanese bamboo (Polygonum cuspidatum) which I try to keep contained by mowing. However, when I found it growing in new locations I became concerned and had wanted to treat the new infestations with Roundup.

Jeff: For your issues I think Roundup would be fine as long as you’re careful of drift.

Reading The Truth About Organic Gardening” made me think about that container of Roundup. I still have problems with tree saplings and Japanese bamboo, but it had been a couple of years since I’d done anything about them.

The container of Roundup (16 fluid ounces, 18% glyphosate) and the rubber cement jar were both in a cabinet in the laundry room, highest shelf, way in the back. Dusty, even. How old was it, anyway? There is no expiration date on the Roundup container. Does that mean it is good forever, or that they want to keep you guessing? The rubber cement jar is labeled “50mL glyphosate (Roundup) 200mL water POISON” in my handwriting, with a hand drawn yucky face. The jar is about three-quarters full, and when I move it I can see nebulous stuff swirling in the bottom of the liquid.

Jeff: Here we have some problems. Do not ever store mixed up pesticides for longer than a few minutes – if you do you will end up with gook that is either useless or dangerous and, worse than that, you won’t have the label in a readily accessible location. This is particularly important because the label includes information on how to treat if there’s accidental contact with the pesticide. Without that information you may seriously delay treatment.

Pesticides that aren’t mixed up can usually be stored for a few years (4-6) before they should be either used or disposed of. Simply using a pesticide (following labeled directions) is often the best way to be rid of it. Pay attention to the directions on the label for how to discard particular pesticides. Some can go into the garbage, some can’t.

The solution in the rubber cement jar represents the second or third mixture I made. I think at least once I got rid of the old stuff in the jar and made a new solution, but I have no idea how I got rid of the old stuff. It says right on the container not to contaminate water, so hopefully I didn’t spill it down the drain. It does say to wrap a partially used container in several layers of newspaper and discard in the trash. But I wasn’t about to throw out my expensive rubber cement jar, and back then I was pretty sure the concentrate in the original container was still good, so I wouldn’t have thrown that out, either. Maybe I put it in an empty jar and screwed on the lid, wrapped it in newspaper, and threw it in the trash. Maybe I poured it on our dirt (originally gravel) driveway.

Jeff: If you followed what was on the label then you did the right thing – the only problem that I have is the rubber cement jar. Sure, it was fine for application. But it really shouldn’t have been used for storage. Applying the pesticide to your driveway to get rid of it isn’t a terrible idea. Once again, applying the pesticide is a legitimate way to dispose of it.

So how old is this stuff, anyway? It just so happens I am a bookkeeper at heart, and have been using financial software (first Manage Your Money, and then Quicken) for years. Consequently I can tell you with authority that I bought it on May 8, 1999 for not quite $15. Gosh, I didn’t think it was that long ago! But I’ve only bought the one container of Roundup, so it must be true.

So, if I want to get back to eliminating tree seedlings and keeping the Japanese bamboo from establishing a foothold in new locations, is the old Roundup concentrate still good? Is it still considered the best solution to these kinds of problems? And is it a responsible solution to multiflora rose, Tartarian honeysuckle, and autumn olive?

Jeff: I think it’s time to get rid of it….I’d get rid of the problems that you mention with a combination of glyphosate and triclopyr (which works much better on some weeds than glyphosate does). I know that I above I recommended using just glyphosate, but when you start dealing with woody/shrubby weeds the added triclopyr will really help. I believe that you can buy this combination as Roundup brush killer (or something similar). But check the active ingredients to make sure.

Are there any pesticide skeletons in your closet? What’s your favorite way to get rid of invasive shrubs? I’m always looking for a better way to tackle this problem.