Alert: Poisoned Soil, Compost, Manure

by Catherine Haug

Deformed Veggies

Earlier this summer, Jean H. noticed something alarming in her garden.  The new growth on her tomato and potato plants were curled and gnarled, and the plants seemed not as strong as they should be.  Her beans, beets and basil, a shrub near her house and several trees, were suffering similarly. What could be wrong? Other gardeners were not experiencing the same trouble.

After giving it a lot of thought, she suspected the problem had something to do with the grass clippings she put around her vegetables as mulch on May 15. But that did not explain why the trees and shrubs were also showing signs of stress and deformity.

Last fall, her lawn had been sprayed for broadleaf weeds; perhaps this had poisoned her grass, which then poisoned her garden and trees. But the company that sprayed her lawn said there was nothing in his spray that could have caused the problem. So, what could it be?

Perhaps the wind had carried something her way, when neighboring fields were sprayed?

Jean contacted the State Department of Agriculture for their expertise, and to have them test her soil and compost. Their test confirmed that aminopyralid was present.

She started pulling all the plants in her garden where she had used her  the grass clippings. Even though some showed no deformity, they could still be affected, and she didn’t want to eat them.  Up came not only her deformed tomatoes, potatoes, beets and basil, but also cabbage, turnips, rutabega and kohlrabi that were not deformed, but had been treated with her suspect grass clippings.

During the investigation by the State Ag department, the sprayer admitted there had been 10 gallons of Milestone in his tank when he filled it with the TriMec spray for her lawn last October. Milestone is an herbicide containing the hormone aminopyralid, that is only intended for use on pasture and rangeland, not home gardens and lawns.

The lawn sprayer will be fined by the state, and he has promised to “make things right” with Jean. Sarah Holden from the State Deptartment of Agriculture recommended Jean not use anything that was even near the contaminated grass clippings and not to plant anything there for 2 years.

So Jean is tearing up more than half her large garden, digging up the contaminated soil and replacing with new soil.  Over 30 years of Organic practices to enrich her soil, now lost.  She must start over.

Aminopyralid found in manure and commercial compost, too

It seems Jean is not the only gardener having trouble from Milestone.

Plants affected by aminopyralid

The following plants are affected (1):

  • Potatoes and tomatoes
  • peas, beans and other legumes
  • Carrots and other umberlliferae such as parsnips
  • Lettuce, spinach and other compositae
  • Dahlias
  • Some species of roses

Cautionary notes

==> This is a relatively new herbicide, so not much is documented about its affect on humans who might ingest it. But like Jean, if you find your garden is contaminated, you should probably avoid eating its produce. And definitely do not sell the produce.

==> Because this herbicide can contaminate compost and composted manure, know your source and its practices.

How to test your soil & compost for this chemical

A simple test using pea seeds can tell you if your soil or compost are similarly contaminated. Don B. forwarded the following article from Washington State University: WSU: Bioassay Test for Herbicide Residue in Compost. See also Don B.’s instructions and photos regarding this Test for hidden poisons in compost, manure, wheat straw.

See also Bioassay for presence of auxinic herbicides (such as aminopyralid) (3 pages, includes photos)

References, for More Info on Aminopyralid

Sara Holden provided the following pdf files on aminopyralid, from Dow AgroSciences, the maker of the herbicide:

  1. Dow AgroScience info for gardeners about garden damage (29Apr09) (6 pages)
  2. Specimen Label for Milestone (8 pages)
  3. Aminopyralid Product Stewardship for Range & Pasture (2 pages)

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