Keep Your Garden Safe From Killer Compost

Learn about the killer compost containing aminopyralid herbicide that has found its way into gardens in the US and Europe.

  • Contaminated Compost
    If the source of your manure-based compost can’t verify that its product is pyralid free, don’t use it!
  • Killer Compost
    If you inadvertently apply aminopyralid-laced manure compost to your garden, you may suffer the crop-killing consequences for three or more years.  

  • Contaminated Compost
  • Killer Compost

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!”



Fall 2021!

Put your DIY skills to the test throughout November. We’re mixing full meal recipes in jars, crafting with flowers, backyard composting, cultivating mushrooms, and more!


Subscribe Today - Pay Now & Save 64% Off the Cover Price

50 Years of Money-Saving Tips!

Mother Earth NewsAt MOTHER EARTH NEWS for 50 years and counting, we are dedicated to conserving our planet's natural resources while helping you conserve your financial resources. You'll find tips for slashing heating bills, growing fresh, natural produce at home, and more. That's why we want you to save money and trees by subscribing through our earth-friendly automatic renewal savings plan. By paying with a credit card, you save an additional $5 and get 6 issues of MOTHER EARTH NEWS for only $12.95 (USA only).

You may also use the Bill Me option and pay $17.95 for 6 issues.

Canadian Subscribers - Click Here
International Subscribers - Click Here
Canadian subscriptions: 1 year (includes postage & GST).

Facebook Pinterest Instagram YouTube Twitter flipboard

Free Product Information Classifieds Newsletters