Keep Your Garden Safe From Killer Compost

Warning: Do not bring manure compost into your garden from outside sources unless you’re certain it doesn’t contain aminopyralid residues!

| April/May 2011

Contaminated Compost

If the source of your manure-based compost can’t verify that its product is pyralid free, don’t use it!


We’ve been reporting since 2008 on the Environmental Protection Agency’s (EPA) failure to prevent Dow Agrosciences from contaminating the public compost supply by selling persistent herbicides, and the issue continues to escalate.

The aminopyralid herbicide known as Milestone, plus other related herbicides collectively known as pyralids (sold under the brands Confront, Curtail, Forefront, Hornet, Lontrel, Millenium Ultra, Reclaim, Stinger and Transline), are still surfacing unexpectedly in gardens throughout the United States, with devastating results. The EPA allows Dow and others to sell these potent weed killers to farmers, who spray them on their pastures and hayfields. When animals graze on the treated pasture or hay, the chemicals pass through the animals and persist in the manure for several years — even if the manure is processed into compost! Gardeners then use the contaminated hay or compost on their crops, bringing a slow death to carrots, lettuces, potatoes, beets, spinach, tomatoes and legumes, including (but not limited to) beans and peas.

This is not a minor or isolated problem. In Montana, laboratory tests confirmed pyralid toxicity in soil samples from 17 counties across the state. Pennsylvania’s state weed specialist has received several reports of contamination, and numerous North Carolina vegetable growers have lost crops to contaminated mulch, hay or compost. Whatcom County in Washington has been hit especially hard, with losses to community gardens and several organic farms estimated at hundreds of thousands of dollars. Those affected think the source of the contamination was cow manure used to produce local composts.

These poisons are so powerful that residues can damage sensitive crops at levels as low as 10 parts per billion, according to an Ohio State University fact sheet. Sensitive plants may show symptoms quickly in heavily contaminated soil, or damage may not be apparent for weeks. As the leaves of affected plants curl and shrivel, gardeners often wrongly assume their plants have been hit by a disease or aerial herbicide drift.

These Toxic Chemicals Contaminate for Years

The EPA gave Milestone/aminopyralid “conditional” approval in 2005, despite inconsistencies in the Environmental Fate and Ecological Risk Assessment submitted by Dow. According to the EPA’s own scientists, “the persistence of aminopyralid [in soil] may be underestimated in this assessment.” Another problem noted by EPA scientists was the risk to endangered native plants. The assessment names endangered plants known to grow in wheat fields, but fails to address a bigger issue: Aminopyralid kills legumes, including wild species that bring nitrogen into the soil, and is consequently capable of crippling nature’s fertility cycle.

At the time aminopyralid was approved, reliable lab tests didn’t exist to identify pesticide residue levels in soil, and today such tests cost several hundred dollars per sample.

peter nelson
7/15/2011 7:17:40 PM

The article title is very MISLEADING. There is absolutely nothing in the article about how to "Keep Your Garden Safe From Killer Compost". Sure, I can write to the EPA but that's not going to do anything to protect my garden. I suggest you either change the title to reflect the article content or add some content suggesting practical steps gardeners can take to keep our gardens safe.

barbara pleasant_3
6/18/2011 9:34:10 AM

I don’t think replanting will help. It may be possible to rescue a tomato or two by digging them up, pruning them a bit, and planting them in clean containers. Sweet corn is less sensitive than other veggies, so you might consider it as an alternative crop. Vigorous grassy warm-weather cover crops like sudex (sudan grass-sorghum) might be useful in rehabilitating your soil. For most people, moving the garden to a new spot is the most practical solution... This is all so very sad. I’m posting another correspondence below. A depressing week.

barbara pleasant_3
6/18/2011 9:30:07 AM

FROM Pam G: “We live in Bellingham, Washington—Whatcom County--which is apparently home of "Killer Compost" as we read in one of your recent articles. We believe we have acquired some such compost as the tomatoes, squash, Swiss chard all are doing poorly. Portions of the row of chard look good, but some seedlings are barely emerging. The tomatoes are a sorry sight. That said, is there anything we can do at this point to remedy the situation save from digging everything out and starting over???? That we don't want to do! We would appreciate your thoughts and ideas!”

barbara pleasant_3
6/18/2011 9:21:15 AM

If it were me I would call Dow (800-992-5994) and raise heck. I would also call the local paper to make more noise. This is the only way to get the product pulled from shelves, prevent danger to other yet-to-be victims, and possibly receive help from Dow. Reportedly they have replaced soil in some instances... This just breaks my heart, but these products are pushed hard for their "vanity" benefits in pretty pastures. Some say intensive cover cropping will help break down the residues, but nobody knows for sure.

barbara pleasant_3
6/18/2011 9:14:30 AM

FROM Joy K-B: “I have a 9 acre farm in York County, PA. We have two horses and two cattle and vegetable gardens. In 32 years we have never used a chemical on the property - strictly organic. In 2010 our pasture had become overrun with buttercups, which was taking over the grass. A landscape contractor recommended Milestone to get rid of the buttercups. In May 2010 my husband sprayed our pasture with Milestone, and we no longer have buttercups... In the fall of 2010 we shoveled the dried manure from the barnyard into feed bags, which were stored in the barn for the winter. Just as we have done for 32 years, we spread the dried manure on the vegetable gardens in early May and tilled it in along with the grass clippings and weathered leaves. I proceeded to plant tomatoes, potatoes, cabbage, peppers, onions, carrots, beans, spinach, red beets, lettuce, parsley and marigolds... It then rained for a week and the plants shriveled up and died. I planted again, same result. The plants curled like fiddle heads, shriveled, and are nearly dead. Interestingly, there are very few weeds growing either. After being puzzled, I read the ingredient in the Milestone and found it was aminopyralid, and have since researched this terrible chemical. How can I remediate my once fertile, organic gardens? I feel like I have been violated because gardening and canning are the love of my life.

5/10/2011 2:15:01 AM

What is scary is that the North Dakota Dept of Ag sends newsletters out and they are really pushing this stuff. I don't want it in my pasture, and I darn sure don't want hay from treated land. That would make my own manure unusable for the garden, then what would I do with it? We tried contacting them and they downplayed our concerns. Right now I am making sure that any hay that I get has alfalfa in it... Since alfalfa is one of the sensitive crops, I feel that hay with it should be safe. And they say there should be a three day wash out period? So that means that it's probably in milk, too. Just what we need... more chemicals in the food chain. I need a cow.

j. landwert
4/17/2011 7:54:52 AM

I take issue with the statement issued by t. brandt that Aminopyralid is "virtually undetectable within 4 months after application" as I am experiencing severe damage to my tomato bed quite probably from using coastal hay left over from last years purchase as mulch. (the feed store I purchased the hay from, and I, are fairly sure that the hay was treated with aminopyralid)

t brandt
3/14/2011 7:29:38 PM

According to the EPA aminopyralid is extemely safe to use on pastures where it is particularly useful against some of the more stubborn weeds. It's half life in field studies is around 30 days, so it's virtually undetectable within 4 months after application, and probably present in less than effective levels long before that. The chemical's label clearly states that there should be at least a three day "wash out period" before using the manure from animals grazing on treated pasture for fertilizer. If some gardens have been hurt by using contaminated manure, it's not the manufacturer's or govt's fault. BTW- your final comment about glyphosate is pure sensationalism and has no place in a supposedly scientific article. Glyphosate is extremely safe- If you're still worried, just don't give it to your Argentinian chick embryos.

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