[permaculture] Fwd: [growingsmallfarms] Persistent herbicides

Lawrence London lfljvenaura at gmail.com
Wed Feb 5 08:16:47 EST 2020


Found in another mailing group, reposted without attribution:
[]

The potential that my raised beds  have a true "killer" ingredient has got
me pretty concerned! I've been aware of something called persistent
herbicides for awhile now, but after a season of poor growth and a recent
indoor test I think I might have introduced some from contaminated manure -
any advice for getting rid of it without digging out all my soil ?

FYI only to learn more about these toxic substances -
What Are Persistent Herbicides?

Persistent herbicides are a narrow range of herbicides used to kill broad
leaf weeds and thistle that compete with grasses and grain crops. They are
"persistent" because they will not be killed by the high temperatures in
thermophilic composting and may take over 2 years or more to fully decay.

There are 4 persistent herbicides:

   - Picloram - Sold as Graslan™, Grazon®, Surmount®, and Tordon®
   - Clopyralid - Sold as Stinger®
   - Aminopyralid - Sold as Capstone™, Chaparral™, CleanWave®, Forefront®,
   GrazonNext®, Milestone®, Opensight®, PasturAll®, and Sendero.™
   - Aminocyclopyrachlor - Sold as Imprelis®

These herbicides are *extremely* potent, with maximum application rates of
only 7-12 liquid ounces....per acre.......per year.

Wow.

And aminocyclopyrachlor, the newest persistent herbicide, will kill a
tomato plant at a concentration of one part per billion. And this stuff is
fast becoming the herbicide of choice for hay and straw producers, which
makes it increasingly likely that horse manure and bedding will be
contaminated with it.

You're probably wondering if there is a test for persistent herbicides. The
answer is "Yes," but it can cost over $300 and is only performed by just a
few labs in the country (Anatek Labs
<https://el2.convertkit-mail.com/c/n4uwdn3oo2svh6kgrmb6/x0hph3ud6l8me8/aHR0cHM6Ly93d3cuYW5hdGVrbGFicy5jb20v>
 and Montana Department of Agriculture
<https://el2.convertkit-mail.com/c/n4uwdn3oo2svh6kgrmb6/k0umh2u2q3gpnd/aHR0cHM6Ly9hZ3IubXQuZ292L0FuYWx5dGljYWwtTGFi>
are
two of them).

There is also a somewhat tedious self-test you can perform at home using
the methods here.
<https://el2.convertkit-mail.com/c/n4uwdn3oo2svh6kgrmb6/2zi2h9u0zerx38/aHR0cHM6Ly91cmJhbndvcm1jb21wYW55LmNvbS93cC1jb250ZW50L3VwbG9hZHMvMjAyMC8wMi9QZXJzaXN0ZW50LUhlcmJpY2lkZS1UZXN0LUF0LUhvbWUucGRm>

The sucky part is that composting will actually concentrate the presence of
herbicides because while organic matter breaks down in the composting
process, the herbicides won't, thereby *increasing* its concentration.

The telltale sign of persistent herbicide damage is "cupping" of broad
leaves like you may find on the eggplant pictured below Hey gang,

I normally like to be the bearer of good news, but the potential that my
vermicompost has a true "killer" ingredient has got me pretty concerned!

I've been aware of something called persistent herbicides for awhile now,
but after hearing even more at the US Composting Council Conference, I need
to be even more diligent when it comes to ensuring I'm not introducing this
stuff to my aerated static pile and CFT.
What Are Persistent Herbicides?

Persistent herbicides are a narrow range of herbicides used to kill broad
leaf weeds and thistle that compete with grasses and grain crops. They are
"persistent" because they will not be killed by the high temperatures in
thermophilic composting and may take over 2 years or more to fully decay.

There are 4 persistent herbicides:

   - Picloram - Sold as Graslan™, Grazon®, Surmount®, and Tordon®
   - Clopyralid - Sold as Stinger®
   - Aminopyralid - Sold as Capstone™, Chaparral™, CleanWave®, Forefront®,
   GrazonNext®, Milestone®, Opensight®, PasturAll®, and Sendero.™
   - Aminocyclopyrachlor - Sold as Imprelis®

These herbicides are *extremely* potent, with maximum application rates of
only 7-12 liquid ounces....per acre.......per year.

Wow.

And aminocyclopyrachlor, the newest persistent herbicide, will kill a
tomato plant at a concentration of one part per billion. And this stuff is
fast becoming the herbicide of choice for hay and straw producers, which
makes it increasingly likely that horse manure and bedding will be
contaminated with it.

You're probably wondering if there is a test for persistent herbicides. The
answer is "Yes," but it can cost over $300 and is only performed by just a
few labs in the country (Anatek Labs
<https://el2.convertkit-mail.com/c/n4uwdn3oo2svh6kgrmb6/x0hph3ud6l8me8/aHR0cHM6Ly93d3cuYW5hdGVrbGFicy5jb20v>
 and Montana Department of Agriculture
<https://el2.convertkit-mail.com/c/n4uwdn3oo2svh6kgrmb6/k0umh2u2q3gpnd/aHR0cHM6Ly9hZ3IubXQuZ292L0FuYWx5dGljYWwtTGFi>
are
two of them).

There is also a somewhat tedious self-test you can perform at home using
the methods here.
<https://el2.convertkit-mail.com/c/n4uwdn3oo2svh6kgrmb6/2zi2h9u0zerx38/aHR0cHM6Ly91cmJhbndvcm1jb21wYW55LmNvbS93cC1jb250ZW50L3VwbG9hZHMvMjAyMC8wMi9QZXJzaXN0ZW50LUhlcmJpY2lkZS1UZXN0LUF0LUhvbWUucGRm>

The sucky part is that composting will actually concentrate the presence of
herbicides because while organic matter breaks down in the composting
process, the herbicides won't, thereby *increasing* its concentration.

The telltale sign of persistent herbicide damage is "cupping" of broad
leaves like you may find on the eggplant pictured below.

Aren't They Regulated?

Yes. And by the EPA's standards, they certainly seem better than the
herbicides that came before them.

These herbicides are toxic to a much smaller number of plants and are far
less toxic to humans and other animals than predecessors like
*2,4-Dichlorophenoxyacetic
acid*, or 2, 4-D for short.

So while persistent herbicides meet the EPA's threshold for safety, that
doesn't mean they can't do a number on your garden if your compost or
vermicompost was created from a feedstock contaminated with persistent
herbicides
What Can You Do About It?

If you're worried about persistent herbicides, the only thing you can
really do is become fully informed about the array of herbicides AND their
known brand names as mentioned above. And THEN research the upstream
sources of your organic waste, *especially* horse manure to find out if
you're affected.


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