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Killer Poop

Pictured: Decomposing barnyard manure. Manure that's tainted with the herbicide aminopyralid from Dow AgroScience will ruin your vegetable garden, even if it's composted.

Pictured: Decomposing barnyard manure. Manure that's tainted with the herbicide aminopyralid from Dow AgroScience will ruin your vegetable garden, even if it's composted.

Dow voluntarily suspended sales of herbicide containing aminopyralid in Great Britain in 2008 but began marketing it again in 2010, this time with stricter directions regarding barnyard manure management (Sullivan). Nevertheless, the problem of tainted manure and ruined gardens persists. Is new contamination occurring despite the new label directions? Does the destructive power of aminopyralid last much longer than formerly thought? Or does the interconnected nature of our world make containment measures moot?

The Scoop on Killer Poop

If you get barnyard manure for your garden from an outside source such as a local farm or stable, be sure to ask if herbicides have been used anywhere the animals have grazed. Also ask if the animals have been fed hay from farms that have or do use herbicides.

One herbicide in particular, aminopyralid, has such plant-killing power that it remains active for years, even after passing through an animal's digestive system.

Adding manure tainted with aminopyralid to your garden will damage and/or kill turnip greens, lettuce, cabbage, broccoli and other broadleaf vegetable crops not only this year, but for several years to come. It will also stunt the growth, deform and/or kill the fruit of other home garden favorites, including beans, peas, peppers and tomatoes.

Just as the digestive process does not lessen the herbicide's killing power, aging and/or composting aminopyralid-tainted manure doesn't make it any less harmful to your garden.

Furthermore, the herbicide's presence doesn't have to be great for it to do serious damage. According to a fact sheet from the University of Maryland, "concentrations [of aminopyralid] as low as 3 parts per million" is all it takes to turn barnyard manure into killer poop ("Gardener Alert").

Brandnames of Aminopyralid

Model of the aminopyralid molecule, a herbicide created by Dow AgroScience.

Model of the aminopyralid molecule, a herbicide created by Dow AgroScience.

Commercial Contamination

Think packaged manure or compost from a greenhouse, garden center or discount house is safer than manure from a local source?

Guess again.

It's probably contaminated, too—if not with aminopyralid, then with clopyralid or some other herbicide. To check it or any other manure or compost for contamination, do a bioassay test before applying it to your soil.

Farmers may not be familiar with the name aminopyralid, but they'll know the name of the commercial herbicide that they used to kill weeds.

According to the Dow AgroScience website, these commercial herbicides from Dow contain aminopyralid: Chaparral, CleanWave, Forefront HL, GrazonNext HL, Milestone, Opensight and Pasturall.

A 2011 article in Mother Earth News as well as a more recent Mother Earth News article on the topic adds these comparable pyralid herbicides to the "beware list": Confront, Curtail, Forefront, Hornet, Lontrel, Millennium Ultra, Reclaim, Stinger and Transline.

If your source of barnyard manure has applied any of these herbicides to land where animals graze, or they have fed their animals hay and other forage from fields where aminopyralid has been used, the resulting manure will turn your garden into a broadleaf plant killing ground—one that won't produce a viable vegetable garden anytime soon.

Stories from Gardeners Who Have Inadvertently Tainted The Soil

How Aminopyralid Works

Ironically, those most adversely affected by aminopyralid damage are organic farmers and home gardeners who have inadvertently contaminated their soil, usually by fertilizing with aminopyralid-tainted manure and/or feeding livestock aminopyralid-contaminated hay.

Amish farmers and others who use livestock in farming have also unwittingly damaged garden soil when their plow animals, unknowingly fed on aminopyralid-tainted silage, defecate in fields as they work.

Is your garden at risk?

Aminopyralid is an auxinic herbicide. It mimics plant auxins, a group of plant-produced hormones that stimulate cell growth and control the development of roots and lateral meristems while suppressing the formation of axillary buds.

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If a plant is left to its own devices, auxins will determine its shape through apical dominance; however, gardeners frequently interfere with this by pinching off terminal buds, thus stopping the flow of auxins and allowing lateral buds to sprout so that the plant "bushes out." Aminopyralid interferes with plant growth in a much less benign fashion.

When plants take up the herbicide's fake hormone, its cells follow aminopyralid's cues for growth, which are aimed, of course, at the plant's malformation and ultimate destruction.

(For a highly technical explanation of how auxinic herbicides work, see Sterling and Namath's "Auxin and Auxinic Herbicide Mechanism(s) of Action - Part 2 - Advanced" in the Plant and Soil Sciences eLibrary.)

A 1947 photo of Dow's highly toxic 2-4 broadleaf herbicide, which was first use on US farms in 1948.

A 1947 photo of Dow's highly toxic 2-4 broadleaf herbicide, which was first use on US farms in 1948.

Following the Directions Doesn't Make It Safe

The labels on herbicides and pesticides (which include not only the actual label but also any fliers or brochures which accompany products) are considered legal documents. Not following label directions means one has no legal grounds for complaint if the product fails to perform as claimed.

Keep in mind, however, that herbicide labels are a combination of the manufacturer's knowledge and the regulator's knowledge of any given product's ingredients at the time of release. Sometimes, as in the case of aminopyralid, that knowledge is incomplete, downright wrong or, as some claim, intentionally misleading.

Furthermore, when actual use reveals the product's true nature, the label information may change. After the damage has been done, of course.

Although Dow AgroScience has changed its labels on pyralid products to address contamination issues, the chemical giant has assumed little or no responsibility for soil contamination and subsequent crop loss.

In thinking about these things, there are three questions I have pondered again and again. Here they are, considerably shorter after the removal of the expletives: Why does Dow persist in producing and promoting aminopyralid and other herbicides in the pyralid family despite continuing public outcry? Why do agrobusinesses purchase and use pyralid herbicides that could potentially ruin their soil and cause them grave financial loss? And why oh why doesn't the EPA demand the removal of aminopyralid and other pyralid herbicides from the marketplace?

Safe Composting & Mulching

If you've treated anything in your yard with any sort of herbicide, don't add it to your compost pile or use it as mulch. It could damage or even kill your garden.

"Weed & feed" products, for instance, may seem harmless enough. However, they leave residual amounts of herbicide in the lawn. Adding the grass clippings to your composter or piling them up around your vegetable plants could stunt and/or deform your plants and their fruits.

Also, if you've gotten manure from a source that's unsure about its safety or the chemicals that might have been in the livestock's feed, test the compost before using it by completing an at-home compost test.



About the Author

The Dirt Farmer has been an active gardener for over 30 years.

She first began gardening alongside her grandfather on her parents' farm. Today, The Dirt Farmer gardens at home, volunteers at community gardens and continues to learn about gardening through the MD Master Gardener program.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2013 Jill Spencer


Jill Spencer (author) from United States on July 10, 2015:

Hi Billy. Thanks for stopping by. Your so lucky! Can't wait until we're out of the suburbs and can have a few farm animals. I'd love to have a few goats and maybe a rescue horse . . . not just for the fertilizer. All the best, Jill

Bill Holland from Olympia, WA on July 09, 2015:

Well we know where our rabbit and goat poop comes from....our backyard, and Rachel Carson taught me well back in the 60s. :) The only problem I see with your articles is that you aren't my next door neighbor. I could use your expertise.

Jill Spencer (author) from United States on July 13, 2013:

Hi W1totalk! It just pays to be careful about what you put in your garden. I read some real horror stories when researching this article. Take care! --Jill

W1totalk on July 13, 2013:

Great article on dangerous poop and how it can effect your garden. Thank you.

Jill Spencer (author) from United States on June 16, 2013:

Rebecca, I hadn't thought of that about foraging! Thanks for reading and commenting.

Hi Rose! Appreciate the vote & the comment.

rose-the planner from Toronto, Ontario-Canada on June 14, 2013:'s amazing what we don't know. It certainly is scary stuff! Great article! Thanks for sharing. (Voted Up) -Rose

Rebecca Mealey from Northeastern Georgia, USA on June 14, 2013:

Interesting and scary at the same time! Thank you for making us aware. This is why I hesitate to eat wild foliage w/0 knowing exactly where it comes form. Voted+++and shared.

Jill Spencer (author) from United States on June 02, 2013:

Although I have no personal experience, Barbara, I did read in several sources that the bagged manure is just as likely to be adulterated. Might want to test it before you use it.

Barbara Badder from USA on June 01, 2013:

Now you've got me wondering about the composted cow manure in bags. I always looked at this as an organic way to fertilize, but maybe it's not.

Jill Spencer (author) from United States on May 17, 2013:

Hi tebo. Some of the interviews w/farmers that I read indicated that the contaminated fields were unusable for broadleaf vegetables up to 5 years running. That could easily put a small farmer out of business! Thanks for commenting. Take care, Jill

tebo from New Zealand on May 16, 2013:

How devastating it must be to realize you have used a product like the ones you mention. It sounds like the once the damage is done it's a long haul back. I don't use any thing apart from my own compost and I don't use any sprays because my dog likes eating grass from time time however I have been thinking about getting some horse manure from the local racecourse. I wonder how safe that would be. Thanks for informing us.

Jill Spencer (author) from United States on May 16, 2013:

Hi Deb! Home gardeners generally don't use these herbicides, which are marketed to agribusinesses. However, they can end up in our gardens and compost if we aren't diligent. Have a great weekend on the lake!

Deb Hirt from Stillwater, OK on May 16, 2013:

Man, we are just killing everything that we have, whether we know it or not. I don't use any of this stuff.

Jill Spencer (author) from United States on May 16, 2013:

Hi Maren. Yeah, everybody wants a quick fix, but even more so, people so often want an unrealistic perfection in their landscape--no bugs at all, none of the spots and bites and "warts" that are just part of a healthy, realistic garden. Nice to hear from you! Hope you're enjoying the good weather. --Jill

Maren Elizabeth Morgan from Pennsylvania on May 16, 2013:

Hi Jill. Two comments -- first, it seems it would take a bit of investigating to determine whether these herbicides were used. Myabe too much trouble. Second, I agree with your comment that Americans were 'taught" to favor chemicals over elbow grease and labor.

Jill Spencer (author) from United States on May 16, 2013:

Hi Eddy! Always nice to hear from you. Thanks for stopping by! --Jill

Eiddwen from Wales on May 16, 2013:

So useful and thanks for sharing.


Jill Spencer (author) from United States on May 15, 2013:

It is a mystery, isn't it, Pearl, as to how post WW II it could ever have seemed like a good idea to turn chemicals created for warfare into pesticides, herbicides & fertilizers for our food supply. Also, it often seems as if people would rather spray a chemical rather than do a little manual labor or tolerate a bit of imperfection in the landscape. Of course, the more serious problem us what's used in by agribusinesses. It's shameful!

Hi Ms. Dora! Thanks for commenting. Please do be aware & always ask what herbicides and pesticides have been used on a farm before getting compost, manure, straw, etc. from it. Take care, Jill

Dora Weithers from The Caribbean on May 15, 2013:

Thank you so much for the warning. This is good to know because we may have problems and not be aware of the reason. It's a shame that people we think we can rely on will deceive us with false labeling and the like. Voted Up and Useful.

Connie Smith from Southern Tier New York State on May 15, 2013:

Jill, thank you for writing and sharing this very important and thoroughly researched article. I wish, hope and pray that someday very soon the powers that be will stop making these horrendously harmful chemical concoctions! I truly believe they are ruining our world with their toxic pesticides, herbicides and fertilizers.

I wonder why they can't turn their knowledge and efforts toward earth-friendly solutions that won't end up killing us all!!

Kudos to you for bringing this to light. Voted Way Up+++ and definitely sharing. Excellent job my friend ;) Pearl

Jill Spencer (author) from United States on May 15, 2013:

It really is scary, Lee, and so ... incomprehensible. I'll leave it to you to write the 2-4D hub. This one's depressed me so. Unfortunately, I have read that packaged manure and compost often does contain herbicide of some sort simply because the use of weed killer is so widespread. We're all going to have to start testing "organic" organic matter before we apply it. ): Thanks for stopping by, Jill

Lee Raynor from Citra Florida on May 15, 2013:

Hey Jill

This is scary stuff, I use some commercial composted manure from the big box stores. Have you heard if that is ever contaminated?

We also have to worry about 2-4D entering the food supply. 2-4D is half of Agent Orange of Vietnam fame and is being promoted as a replacement for Round Up because so many weeds have become tolerant.

Products grown with these poisons should come with warning labels and the FDA does little to protect the people.

Meanwhile I've been stocking the freezer with lots of veggies from the garden.

Voted up and awesome


Jill Spencer (author) from United States on May 15, 2013:

Hi Glimmer Twin Fan! Aminopyralid doesn't seem to have any harmful effect on animals or people, although it can cause eye/skin irritation if not handled properly during application. It does, however, ruin the soil for growing broadleaf vegetables.

Claudia Mitchell on May 15, 2013:

This is really quite frightening. I'm beginning to wonder if we should just grow our own fruits/veggies and forget the stores. It makes me wonder what else is in our food. This is a really informative hub for gardeners. Up and shared.

Jill Spencer (author) from United States on May 15, 2013:

Hi Faith Reaper! The silly title is just my way of being a little cavalier about something that absolutely makes me want to cry. The problem of contaminated manure is bad enough here in MD now that it's causing some alarm & was a topic of discussion at an MG meeting. After that, I started researching. Also, last year my mother-in-law complained to me about her tomato plants growing okay until bloom time, when they began to become distorted & produced twisted buds that dropped off. This year while visiting, I noticed that she had grass clipping piled up around them, which she says she always does to feed the plants. A great idea, but not if you use Chem Lawn. We need to do a soil test, but ... I bet herbicide in the clippings is the problem.

Thanks for reading, Faith! And for sharing the hub. Knowledge is power!

Faith Reaper from southern USA on May 14, 2013:

Boy, that title there grabs one's attention no doubt! That is really sad though, especially the ones who do not realize what they have done!

You are so wise in these areas with your many years of experience and thank you for sharing such knowledge with us all.

Voted up +++ and sharing

Blessings, Faith Reaper

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