MotherEarthNews says Dow & DuPont are poisoning American compost

ZoysiaSod(6a/6b St.Lou TranZone)April 27, 2013

You can check out this critical story at the Mother Earth News web site:

Some quotes from the story:

"We need to demand that the Environmental Protection Agency ban the potent, persistent herbicides that continue to contaminate commercial compost and manure supplies."

"For more than a decade, gardens and farms have been damaged by compost or mulch that was contaminated with persistent herbicides. These potent chemicals are applied to lawns, pastures, hayfields and roadsides, and continue to be highly toxic even after residues on grass or hay have been composted. When livestock graze on treated pasture or hay, these herbicides even remain potent in their composted manure. We’ve termed this recurring problem “killer compost.”

"In June 2012, employees at Green Mountain Compost in Williston, Vt., began fielding reports from gardeners about suspected herbicide damage following application of compost purchased at the facility. Initial tests of the compost revealed the presence of two herbicides ��" picloram and clopyralid ��" known to be persistent in compost. Green Mountain, which is now under the management of the Chittenden Solid Waste District (CSWD), immediately suspended sale of its bagged and bulk compost and began seeking the source of the contamination. It also started making reparation arrangements with customers who had reported damage. Picloram and clopyralid are produced by Dow AgroSciences to control broadleaf weeds on turf grass, pastures and rangelands."

"So how did these chemicals turn up in the compost? In early August 2012, CSWD identified area horse farms as the source of the contamination and sent letters to those farms indicating it could no longer compost their manure. Puzzled as to how the herbicides had gotten into the manure, CSWD asked those farms to indicate which commercial horse feed they had used, and then took the bold step of having samples of that feed tested. Bingo. According to initial lab results, several samples of off-the-shelf Purina horse feed were contaminated with clopyralid at levels between 142 and 465 parts per billion! Susceptible garden plants ��" such as beans, eggplant, peas, peppers, potatoes, sunflowers and tomatoes ��" are harmed at exposure levels as low as 30 ppb, five to 15 times lower than the levels detected in the horse feed."

"CSWD also sent the same lab ��" Anatek Labs Inc. in Moscow, Idaho ��" 84 samples of compost from other regional facilities as well as common local compost feedstocks, including bedding, manure, hay, straw and municipal grass clippings. The lab found picloram and/or clopyralid in 67 out of the 84 samples ��" 80 percent! Meanwhile, on behalf of the Vermont Agency of Agriculture, Dow sent samples of manure, manure with bedding, compost, feed, hay, grass, and straw collected from across Vermont to its own contracted lab, Carbon Dynamics. The tests detected no picloram, but did find low levels of clopyralid in five samples, all of them commercial livestock feed."

"Dow voluntarily withdrew clopyralid for legal use on residential lawns a decade ago following compost contamination issues in California, Pennsylvania and Washington state. By 2004, levels of clopyralid in compost had dropped significantly across the Pacific Northwest thanks to tighter label restrictions. But then in 2010, Washington state farmers were hit again, this time with another Dow plant-killer, aminopyralid, and tainted compost caused extensive crop damage on organic farms and gardens. In 2011, DuPont (not Dow) began aggressively marketing another similar compound ��" aminocyclopyrachlor ��" under the brand name Imprelis.

The chemical companies consider these highly persistent herbicides “green” because a little goes a long way and because they remain effective over time. This staying power actually turns out to be an enormous problem."

"It's Time to Outlaw Persistent Herbicides

We simply cannot allow chemical giants to continue to peddle such persistent and powerful pesticides. It is well past time for the EPA to fix this problem. The solution is simple ��" stop allowing companies to profit by selling these plant-killers while hiding behind “do not compost” warnings buried in nine-page labels. Our guess is that while the Composting Council agrees with us, it doesn’t want the public to know about this issue because then we might stop buying its products. Well, as much as it pains us to say it, we believe the time has come for the public to stop buying compost or manure products unless they come from suppliers that are able to afford testing and can screen feedstocks for herbicide residues. A few companies have told us this is the only way they know of to deliver safe compost to their customers, but the added costs for testing make competing tough. And now we’ve learned that these Dow and DuPont herbicides are even contaminating our livestock feeds!

This has to stop. Clearly, EPA labeling requirements and state regulations aren’t working. Recycling organic wastes to maintain soil fertility is essential if we want a sustainable food-production system. Picloram, clopyralid, aminocyclopyrachlor and all similar chemicals should be banned, period."

There's more info about this compost poisoning at the link shown above.

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I posted an article about this on Thursday on "this thread" but it certainly bears repeating.

The only way to have safe compost is to either make sure the supplier labels their product as safe or make your own compost using animal manures or grass clippings that are not chemically polluted.

    Bookmark   April 27, 2013 at 1:51PM
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It is a huge issue and getting larger. A local organic grower got burnt by feeding his horse hay he cut from a ditch. You guessed it, the ditch was sprayed with a long lasting herbicide. So now one also has to be cognizant about where the feed they give to their animals comes from. My neighbor has used Lontrel on his wheat so that means his straw is therefore considered contaminated. Anyone who uses his straw for bedding will now have contaminated manure.

I literally get tons of grass clippings and I can only hope that some of the homeowners have not broken the rules and applied a herbicide that they should not have access to. It scares me, but I hope that going with a two year composting process helps to alleviate any chance I will pass on these chemicals. Unfortunately there is no guarantee.


    Bookmark   April 27, 2013 at 2:18PM
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Mother Earth News is late to the game. The carryover issue has been known for several years, especially in the Pacific NW. The problem has been acknowledged by Dow AgroSciences and others. It was specifically that reason (carry over in grass clippings) that clorpyralid was removed from residential use. What was not anticipated at the time the product was registered and then modified was the use of plant materials and manures with carryover amounts in composting.

My suspicion is that this will result in further restricted use of clorpyralid and similar products. If the remaining use market is too small, then the products will be withdrawn.

Let me suggest a couple of less emotional, more factual references:

1. From Oregon State University

2. From Washington State University Island Co. Extension - link below

Here is a link that might be useful: Clopyralid and Aminopyralid Herbicide Residues Found in Manure and Compost

This post was edited by TXEB on Sat, Apr 27, 13 at 14:52

    Bookmark   April 27, 2013 at 2:26PM
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If they compost correctly, it's broken down and gone...or at least broken down to a level that's harmless even to seedlings.

I have consulted and visited many compost facilities that have NO business doing what they're doing because they don't do it properly.

The worst offenders are private composting companies that do not have the proper equipment to turn their piles and will source materials from anywhere regardless of brown/green ratios.

I've been to so many compost sites that have these HUGE piles that are solely "turned" with excavators or a front end loader. While this can work with some piles, we're talking about trying to manage piles that are 10+ foot tall and are too big of a job to turn with these types of machines without losing the heat of the pile. When that issue compounds with improper green/brown ratios making up the pile you get a pile that stays too cool for too long.

When you're using uncomposted sources you really have to watch your source...and when you get compost you really need to know the supplier is doing it properly.

    Bookmark   April 27, 2013 at 4:29PM
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I'd like to piggyback this comment with a note about one herbicide...Imazapyr.

Imazapyr is extremely safe (as far as herbicides go) for the home consumer. It's one of those herbicides that's very hard for a careless consumer to screw themselves up with. You can ingest small amounts of it with little/no effect...if you splash some on you, it's no issue to most people...etc etc's extremely long lasting and probably the most powerful herbicide on the market available over the counter.

A lot of people are very weary about giving the consumer such a powerful herbicide even if it's hard to make yourself sick using it improperly.

This stuff can take down a full grown tree. It's very powerful and rather persistent.

Even though the human/environmental impact of it is rather benign, the fact it's showing up in a lot more products is giving some people a bit of concern.

If it gets more popular, it could cause a bit of issue in re-purposed/composted/etc goods that contain a large amount of it even when composted properly. It really needs time, as well as the extreme temperatures/moisture to properly break down.

    Bookmark   April 27, 2013 at 4:38PM
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I completely agree with you on the issues of composting in general (a lot of variation, poor control, not so great practices), and on herbicide degradation in composting in general. That said, there are issues with some herbicides, and the pyridine carboxylic acids (clopyralid, aminopyralid, picrolam, etc,.) have proven troublesome in composting.

By design, those herbicides are moderately persistent. That has distinct use advantage in their intended applications. The problem comes in carryover to uses that were never anticipated when they were created, studied, tested, registered and brought to market, 20 years ago, coupled with the vast difference in sensitivity to those herbicides in crops that should never have been exposed to those herbicides vs those for target use.

For clopyralid the typical carryover in treated crop residues is one the order of 1-10's of ppm. In healthy aerated soils the average half life is 25 days, with a 95% c.i. of 69 days. Studies of degradation in composting are widely varied, but one very good study gave half lives on the order of 10-30 days, and it's on the lower side relative to others (some others give the t 1/2 of a year or more).

For the sake of argument let's use a 30-day half-life in composting and an input of 10 ppm on half the feedstock, net= 5 ppm. After 3 months the residual would be expected to be ~ 300 ppb. The issue is that clopyralid and aminopyalid have demonstrated phyotoxicity at less than 300 ppb in sensitive pants, including cucumber, lettuce, tomato, peas, beans. and red clover. Hence in sensitive crops phytotoxic levels of that selected class of herbicides can carryover through even well run composting operations. It only gets worse in poorly run composting operations.

A related issue is the historical consideration of environmental toxicity. Environmental dispersion to the atmosphere and water, as well as mammalian, avian, aquatic, etc. toxicity via the usual modes of transport have long been considered. However, historically carryover through composting from either crop residue or manure was not a consideration. The growth of composting as a commercial enterprise and by municipalities as part of solids waste management adds a new dimension to consideration of environmental fate and consequence.

    Bookmark   April 27, 2013 at 8:56PM
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The composting facility in question was probably not used to handling materials containing a lot of clopyralid or picloram.

It seems they picked up a lot of it from manure sources...and it coincided with the national hay shortage. It's a little bit of a leap (though not a wild leap), but some livestock sources may have gotten a lot of imported hay from areas where clopyralid and picloram use is a lot more prevalent...and the compost facility therefore not expecting the increased time they need to "cook" their compost. A hot/moist pile is crucial to breaking down clopyralid/picloram.

The Purina Horse Feed was implicated in the story, too...that was probably from broadweed control on alfalfa fields.

The facility seems to have been caught in a "perfect storm" of sourcing (and sourcing quality) issues on all sides one wouldn't normally expect.

Given the feed supply crunch and how much Purina Horse Feed is sold nation-wide, it would be a bit amazing more facilities didn't get "stung" by this issue. It's hard to call out that one facility, but it seems they might have been getting too much "browns" from manure/straw and not enough greens from yard waste when they were batching out that compost. It's more of a leap than the "hay thing" mentioned above to jump to that conclusion, though, because I've never seen/heard anything about how that facility uses available inputs.

This post was edited by nc-crn on Sat, Apr 27, 13 at 22:01

    Bookmark   April 27, 2013 at 9:52PM
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Btw, I'm not trying to totally dismiss the issue of residual herbicides in compost/'s an issue that deserves attention.

It can end up being very costly to suppliers and consumers playing lawsuit-and-payout tag when something large-scale such as this happens and it's economically and environmentally significant.

    Bookmark   April 27, 2013 at 10:05PM
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The first reported issue came in Spokane back about 12 years ago. The major source found then was from residential grass clippings - clopyralid had become an herbicide of choice for residential use in WA. and grass clippings were being collected for municipal composting. After study, the issue was found more broadly, but again concentrating in the west coast (CA & OR) where municipal composting was on the rise.

In 2003 OR DEQ did a study with help from Dow AgroSciences on methodology and found clopyralid levels in 12 municipal compost ranging from 6-94 ppb.

· 5 facility samples between 6 ppb and 25 ppb
· 4 facility samples between 25ppb and 50ppb
· 3 facility samples between 50ppb and 94ppb

Bioassays using peas and beans found adverse effects in most samples, and using red clover (the most sensitive) found adverse effects in everything.

I'm not sure about hot/wet composting conditions, but Dow AgroSciences states that it won't decompose in stacked manure. They also state a 12-month wait after application of aminopyralid to grazing pastures before it can be considered residue free. It seems that the right aerobic microbes are essential, once it is free of a host matrix. My impression has long been that aerobic conditions are more important than elevated temps, but that's just a SWAG.

Part of the issue is who is at risk. While we tend to think of our gardens, the upstream risk of contaminated compost is huge for municipalities that are increasingly using composting as part of their solids waste management plans. They will be increasingly protective of those waste streams to retain the value of the compost products - a point made clear in the OR DEQ study noted above. For that reason, the pertinent herbicides have been largely banned in WA, CA and OR.

A reasonable overview study was published by a UK group in 2009 - it provides a good summary of other studies and findings (i.e., well referenced) - link below

Here is a link that might be useful: WRAP Study

This post was edited by TXEB on Sat, Apr 27, 13 at 22:36

    Bookmark   April 27, 2013 at 10:29PM
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From my own experience, in some areas (too many) there's extremely lax animal farmer and straw/hay grower attention paid to wait times after applications of systemic herbicides in the rush to get animals to pasture or a hay crop in the field after clearing the "main" crop. In areas where they're battling thistle and other pasture broadleafs, way too many don't follow these wait times. Technically, they're not follow afoul of the law doing this, but like GMO cotton growers who insist on growing 100% BT cotton rather than 20-50% (depending on area) mix of non-BT GMO cotton along with the BT's up to the farmer to follow this suggestion.

The "label and the law" only stretches so far and most of it is for application and critical periods. It doesn't surprise me at all we're getting more of these herbicides in our animal feed system...and residual residues working their way into our compost/amendment system.

    Bookmark   April 27, 2013 at 10:40PM
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nc, prexactly!

As a result of the "discovery" made with the pyridine carboxylic acids, and the growth in importance of composting as a solid waste disposal stream, I have no doubt that new product research and registration will include carryover effects into animal manures, grasses, and anything else deemed important to composting.

One of the biggest problems that the ag chem suppliers face is misuse / abuse of their products. Often that arises from residential overuse or misuse. When it becomes broadly problematic, as it did with chlorpyrifos, we lose the product.

But, it's not always the unknowing homeowner. About 35-40 years ago one of the ag chem majors introduced a new broad spectrum ag herbicide. It was unusual at the time because of its potency. If I remember it had an application rate of something like 5 g/acre, and a 30-day wait before till after application. One seasoned (aged) farmer in the local area determined that the instructed rate was a typo, and he upped the mix to apply 10X the instructed amount. His field laid dormant for 3 seasons before he could plant it again.

The instructions and restrictions are there for a reason. If users would appreciate that, we would all be a whole lot better off.

This post was edited by TXEB on Sun, Apr 28, 13 at 7:48

    Bookmark   April 27, 2013 at 11:19PM
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nc and TXEB you both need to do some better research since the products discussed in the article do not break down in the composting operation and are known to kill plants in the gardens they are used in.

    Bookmark   April 28, 2013 at 6:33AM
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kimmsr - if you go up high enough and read through it, I believe you'll see your points were covered, with references included.

Pyridine carboxylic acid herbicides do break down in a well operated, aerobic composting operation. But the breakdown is slow and incomplete, and there can remain residual amounts at levels that are phytotoxic to a number common crop plants.

This post was edited by TXEB on Mon, Apr 29, 13 at 17:12

    Bookmark   April 28, 2013 at 7:34AM
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The products do break down with proper time, hastened greatly by heat and moisture.

With the amount of clopyralid used in the mid-west and south-east we'd never have usable compost if this wasn't the case. It's one of the most popular clover-killers in the south-east and thistle killers in the mid-west.

There seems to be a lot of issues with composting these products in cooler climates (north-east/north-west).

    Bookmark   April 28, 2013 at 4:49PM
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Compost that was 5 years old that had these poisons were found to still kill off the plants in the gardens that compost was applied to. How much time is needed to not need to be concerned and why should people need to be concerned that the compost they are buying might destroy their garden?
Like BP Dow and Dupont spend a lot of money on ads trying to convince us they are environmentally responsible corporations but many of us do not believe them even with the help of some of these apologists that appear on these forums.

    Bookmark   April 29, 2013 at 7:17AM
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kimm - I didn't see any "apologists" in the above. What I do see is a lot of factual information.

"Compost that was 5 years old that had these poisons were found to still kill off the plants in the gardens that compost was applied to."

Can you tell me where and when this occurred? How was it established that the problem was "these poisons" (I assume you mean the referenced pyridine carboxylic acid herbicides)? Is there an available report of this account I can read?

    Bookmark   April 29, 2013 at 8:30AM
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"How much time is needed to not need to be concerned and why should people need to be concerned that the compost they are buying might destroy their garden? "

If composted properly, months...if not composted properly it could be years, evidently.

This one facility had an issue...some others have had issues in the past.

The use of Purina Horse Feed, the manures that come from that feed, straw/hay, and these herbicides are not only used in that 1 facility. They didn't get the entire US supply of those sources.

If your source materials don't get your pile hot enough...if you sell your compost before it's "done"...if your pile is unbalanced and never gets a chance to properly compost...if your pile isnt' moist're going to have these issues if you have herbicide contaminated compost.

This would be a nation-wide issue rather than a single supplier issue if it was a "lingering for years" issue that couldn't be solved by proper composting.

This seems to happen every few years with a supplier, and a whole lot of these suppliers seem to be located in cool/cold climate areas.

    Bookmark   April 29, 2013 at 4:27PM
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Several reputable composting operations have been affected by these long life herbicides. It is a problem, no one knows for sure how these products really biodegrade, the issue is still being studied and people have a right to be concerned.


    Bookmark   April 29, 2013 at 7:47PM
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"no one knows for sure how these products really biodegrade"

Actually, they do. Like any soil science, though, there's a huge amount of variables in play from the amount of heat/moisture all the way to how the soil/compost, itself, supports or hinders microbial and nutrient exchange action that act upon certain herbicides.

One of the most crucial tests done on any herbicide is determining breakdown variables/times and mode of action to achieve it. It's really important to know this stuff if you're cropping.

    Bookmark   April 29, 2013 at 8:12PM
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The problem is indeed quite real, and justified. Actually, quite a bit is known about their biodegradation to those who have done the hardcore research, but that information is not available in the readily or easily accessible public domain. That knowledge is critical for crop rotation impact, and is part of the registration package. Even known, however, it doesn't do much for the large-scale municipal compost operation. The issue there is presence in feedstocks.

The real problem is how affected grasses, or in some cases grains, are used. The herbicide products are being re-registered with labels that would preclude the use of treated grasses/grains in composting. That doesn't relieve, however, the issue of those same grasses being used as animal feeds, and then the animal byproducts (manures) being used in composting. At the composting end, the challenge is tracking from use to feedstock, including animal pass-through.

This was not much of an issue when persistent herbicides were introduced in the 60's and 70's (1964 for picloram; 1975 for clopyralid), because there wasn't much large-scale commercial composting going on. In subsequent years, starting ~ 2000, composting came to the forefront primarily as a viable option to manage solid waste disposal. As a result, the scope and breadth of environmental fate and toxicity now needs to consider carryover into and through composting, which had never been an issue. We live, we evolve, and we learn. My suspicion is that pesticide resistance in general, and it's impact on solid waste disposal that includes composting, will become an increasingly important consideration for manufacturers and regulators both.

    Bookmark   April 29, 2013 at 8:34PM
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zeuspaul(9b SoCal)

What about the 6 bales of straw I purchased for mulch? Do I have to test for herbicides? And what about alfalfa pellets, do I have to test them too?

It seems like uncomposted grasses and grain would be at greater risk. What is the likelyhood a random sample would have one of these herbicides?


    Bookmark   April 29, 2013 at 8:57PM
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An added note on persistent herbicides in general -- aside from the issues in composting specific to pyridine carboxylic acids -- there is a growing concern among farmers about persistent herbicides and the impact on crop rotation options.

For example, in ND, a number of wheat farmers had been using chlorsulfuron, which is a fairly persistent herbicide not implicated in composting issues (at least as far as I know). Farmers really liked the fact that in many cases they were still seeing good control a year-plus after application. That meant money saved. Then came the scab problem (fusarium head blight). For many that meant they need to move away from wheat to other crops. However the persistence of chlosulfuron meant they couldn't rotate to valuable broadleaf crops (soybean, sunflower, canola, etc.). Reports have been that is some cases it took as much as four years before the fields that had been treated were again viable for the desired rotations.

Herbicide persistence can be both a blessing and a curse. With the growth and importance of municipal composting for solid waste disposal, it seems the latter may be winning.

    Bookmark   April 29, 2013 at 9:13PM
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zeuspaul -- focusing only on the specifics, not the broader argument ...

Alfalfa shouldn't be a problem -- alfalfa is in the legume family (pea, beans, clover), which is extremely sensitive to the pyridine carboxylic acids.

Straw - could be a problem, depending upon the type of straw (oat?)

This post was edited by TXEB on Mon, Apr 29, 13 at 22:05

    Bookmark   April 29, 2013 at 9:44PM
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"there's a huge amount of variables"

That reads like we don't really know how these things degrade.


    Bookmark   April 29, 2013 at 10:04PM
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"That reads like we don't really know how these things degrade."

It shouldn't read like that because we know how they degrade.

It's a key part of rolling out a herbicide. It's like putting an odometer on a's crucial. It's not an afterthought or something done by a 3rd party.

This is crucial information to farmers. Your herbicide selection can limit what you can grow on your land following the application...from weeks, to years.

Let's throw this another direction...

How many people on this soil forum have come in here talking about the "compost" they bought that wasn't even fully broken down?

Improperly done composting happens a lot more than it should. There's a lot of people out there not sourcing correctly, sourcing too much one single industry/source, and especially not cooking their compost correctly. How about let's look at that aspect of the formula? We see it enough on this very forum.

We had 1 major incident in 2012 with the referenced composting facility. Were they the only people dealing with these herbicides? No. Were they the single composting facility for contaminated source materials for the entire nation? No. Were other composting facilities dealing with this issue? Yes. Did their compost cause mass crop kills? No.

This post was edited by nc-crn on Mon, Apr 29, 13 at 22:30

    Bookmark   April 29, 2013 at 10:25PM
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A couple of questions: first, how much fungal, as opposed to bacterial, activity can degrade these persistent pesticides? and second, do these pesticides attack trees?

I am asking because I am planting about thirty fruit trees over the next ten days. The soil, cleared woodland, was positively contaminated with juglone and killed some of the trees last year. I decided to amend every hole to speed juglone decay.

Well, you probably guessed it. I brought in a pile of leaves, then when I realized it would not be enough, I brought in about 2 tons of 4 months old horse manure. As far as I can tell the manure sat in a pile through the winter.I have not applied it yet but I am starting Saturday. Advice? The trees are virtually every common Michigan fruit tree, apples, pears, cherries, peaches, grapes, persimmon, pawpaw. I can mix it with the about 30 tons of wood chips in the orchard, which have been sitting there for a year, one of the loads was certainly not black walnut chips.

    Bookmark   April 29, 2013 at 10:45PM
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Part of the challenge is that the rise of composting as a method of solid waste disposal and increased demands for various feedstocks has added new dimensions to the term biodegradation.

Historically, new pesticide registrations considered extensively biodegrading in soils, as well as aquatic systems. Those have been extremely well studied, and in the case of the pyridine carboxylic acid herbicides biodegradation in those environments is pretty well understood. Nobody even remotely knowledgeable should be surprised that it depends upon a number of variables - pH, temperature, moisture, etc.

Now let's enter the domain of composting - a whole new environment in which to think about "biodegradation". The variables are more diverse. And now, it's not just biodegradation, it's a whole new chemistry set that includes a host of non-biological reactions leading to humification. Furthermore, now we need to consider that the herbicide in question isn't a free molecule in the "environment" under study (compost), but is somehow sequestered in a plant matrix or animal byproduct. So the first question becomes how does the molecule even become accessible for any form of degradation? The composting environment is very different than that of soil when it comes to "biodegradation", and in fact much of what happens in composting is purely chemical transformation that follows the bio part.

Trying to simplify the points, when it comes to biodegradation the composting environment is very different than soil, and it is far more complex and variable. We are still learning about the composting environment - compared to the soil environment it is a very new field of study.

This post was edited by TXEB on Tue, Apr 30, 13 at 3:09

    Bookmark   April 29, 2013 at 11:05PM
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The problem with trying to nail down times for decomposition in composting as far as an industry standard is it's wide open as far as how well different operations actually manage their compost.

There's nothing that says a compost facility has to do their job properly. Some composting facilities I've seen should just be called "rotting" facilities. They make piles and wait for time to take it's course. Some mix a lot of construction scraped top soil in their mixes because all the incoming yard/lot/construction waste is treated the same...whether it be a truckload full of tree scraps or a truckload full of topsoil scraped from a construction site.

Way too many compost sites, especially private ones, have way too few sources and their mix isn't ideal (and in some cases poor). You'll have operations that get all this free manure and straw from horse operations...and that's almost all of their source rots more than it composts (though technically it is composting). You'll have other operations that operate almost solely on yard wastes and a whole lot of these sell a lot of "unfinished" compost because their piles never heat up enough.

In order to lay a standard...or even a time for would require a whole slew of "If this is how you do it, this is what you can expect" scenarios. The commercial composting industry is a lot more "wild west" than it should be.

    Bookmark   April 29, 2013 at 11:24PM
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glib - getting back to something practical ...

I'm not sure the exact mechanism of the biodegradation (species responsible) of pyridine carboxylic acid herbicides is well known.

Do they attack trees ? One member of this class is triclopyr, which will definitely kill a peach tree if it is soil resident and available for translocation (personal experience). The others, I don't know. However I would not expect triclopyr to be an issue with horse manure - it's not a grazing pasture or grassland application herbicide.

My recommendation would be to take whatever the planting mix will be in the hole and do a bioassay using either beans, peas, or preferably red clover if you can get the seed. If any of those will germinate and grow well through 3-4 weeks relative to a control (soil absent the amendments) then I would expect you will be fine.

What part of MI?

    Bookmark   April 29, 2013 at 11:51PM
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Almost every herbicide/pesticide (or herbicide/pesticide class/family) will have different mechanisms for breakdown.

Some breakdown on exposure to light. Some break down with extreme moisture...some reside longer lived in moisture. Some are susceptible to breakdown by some types of bacteria and other types do nothing. Some can be broken down by yeasts...fungi...chemical interaction and reaction with soil nutrients...etc... Many are accelerated in breakdown regardless of mechanism with heat...this is true about many processes, though...chemical reaction in nature or biological in nature (or, usually, a combo of both) up until a certain point that too much heat stops this process (which is rare outside of lab simulated conditions).

The type or class/family of chemical gives the best indication to known mechanisms of breakdown.

A lot of it has to do with what of the long chain molecule is that makes the chemical, what weakens/breaks them up, what their sub-products/byproducts are during their breakdown, how long those sub/byproducts last, and how dangerous or inert those sub/byproducts are to what host/target you're investigating.

This post was edited by nc-crn on Tue, Apr 30, 13 at 1:07

    Bookmark   April 30, 2013 at 1:02AM
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glib - adding to my previous comments ... the issue as I understand it is that you intend to use aged horse manure as a soil amendment at planting time - is that correct?

What we know about the degradation of the common use pyridine carboxylic acid herbicides is that they do NOT readily degrade in an anaerobic environment. That includes stacked manure. That was specifically the problem in the UK with aminopyralid - it didn't degrade in those piles that had been sitting there for even a year. Given what happened in VT and what was traced back through to commercial feed, unless you know what the horses were fed and know the source of the components of that feed, and further know that nothing was treated with one of the herbicides of concern, it should be suspected that it could well have residual amounts of those herbicides.

As far as the potential impact on the fruit trees you intend to plant, I found that Stinger herbicide (clopyralid - link to label below) is registered for use on stone fruits (peach, cherry), but no mention on the others you listed. It is actually recommended for fall treatment in appropriate fruit orchards by MSU Extension. You may be able to get some help on that from the folks at MSU. However, the problem in your case is that if the manure was contaminated you would be adding it to the intended planting root zone, which I doubt has been studied.

I would think that a bioassay of the planting soil amended as you intend, vs. a control, using common garden sweet peas would give you the insight you need, but to do that right will probably take 4-6 weeks. Again, the Moo U folks can probably guide you on that.

Here is a link that might be useful: Stinger herbicide label

    Bookmark   April 30, 2013 at 8:42AM
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Thanks, this is useful. Indeed last summer I bio assayed with tomatoes and petunias to nail down that juglone was responsible (the leftover woodland also had identifiable BW). That, plus the fact that peaches survived (2 out of 3), while apple trees died, led me to the conclusion. I also had asparagus all along the perimeter, and the row on the woodland side died off, whereas the row on the road side (in extremely poor soil) is 100% alive. I dug a trench between woodland and orchard, pruned all roots, I have planted a row of austrees to have a living barrier, and one year of wood chip cover in the orchard has injected substantial fungal mass.

I can sacrifice a few of my existing tomato transplants today, and get clues by Saturday. I always start too many anyway. I also have 36 transplant peach trees from seed, not intended for the orchard, two of them are going to be tested too. I can also look at the clover around and under the manure pile, which has been there two weeks, not enough to kill a perennial by simple smothering. This is probably going to be the strongest evidence.

    Bookmark   April 30, 2013 at 9:38AM
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glib - one more, from what I've read red clover germination is fairly sensitive to the presence of those herbicides. If you have a good feed store nearby they may have seed, and it should give you another data point in 5-7 days.

    Bookmark   April 30, 2013 at 9:48AM
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Two references that those with an interest may find helpful or informative:

1. Pyridine Residue Management factsheet from Dow AgroSciences, that includes articles from NC State and Univ. of Minnesota.

2. A simple Bioassay Test for Auxinic Herbicide Residues in Compost from the folks at Washington State University via their Extension service.

    Bookmark   April 30, 2013 at 8:57PM
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So far I have two peach and two tomato transplants in manure. These are older transplants, roots were present all over the outer surface of the soil block. They have suffered some cold and have some purple (P deficiency), I should see right away if they are drawing nutrients from the manure, the color will change. The manure pile was mostly on wood chips, I found three clover plants (I seeded the orchard with clover last year) at the edge, they looked fine. Grass and thistle were coming through with no problem. I actually have some leftover clover seeds from last year, so tonight there will be another test.

I am anyway interested (academically) to find out if fungi can degrade these things, I will look at the literature you provided. Thanks for the help, and for a previous unanswered question, I live near Ann Arbor, MI.

    Bookmark   May 1, 2013 at 9:46AM
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Zingerman's! Cool . Reason I asked is I lived in mid-MI for a dozen years, and loved it.

On degradation here is what I've been able to glean. The key is aerobic degradation, but nothing I've seen in the literature is specific about which species dominate. There was one report using controlled culture trials that demonstrated complete degradation of picloram by one species of yeast.

When free clopyralid or aminopyralid is added to the soil surface in typical soil environments with average moisture and normal temps, the half-life is in the range of 30-60 days. Sunlight doesn't appear to affect the degradation. Trials conducted by addition of free clopyralid to compost mirrored soil trials.

Other effects that have been reported are the rate of decomposition is slower at higher herbicide concentrations, suggesting some self-inhibition effect at higher soil concentrations. Perhaps more important to the manure and compost question is that the rate of decomposition is apparently suppressed by higher levels of organic materials in soils; the suggestion has been that the herbicides actually get tied up with organic matter making them less available to microbes for digestion.

In anaerobic environments biodegradtion is largely non-existent. That is likely the dominant reason that aminopyralid doesn't decompose in stacked manure (suggesting to me that the problem would be most evident with manure taken from the center area of a large pile).

From other less robust research it has been suggested that when the herbicides are introduced into composting via either manure or as residual in treated grasses or grain residues that biodegradation does not take place through the thermophilic stage, but rather ensues later during maturation. The reason for that isn't known- it may be microbe dependent or it may be that the herbicide molecules just aren't available by being tied up within the host matrix, and until freed there is no decomposition. That may possibly also explain the apparent long retention periods that have been observed within affected manures, and the persistence after composting of either treated grasses or manures, but it isn't known.

So the key is aerobic, and getting the herbicide free of any plant or manure host, meaning degrade those items to free the active herbicide.

An aid may come from the fact that clopyralid and aminopyralid both move readily with irrigation/water, suggesting to me that the free stuff in soil can be readily leached. In aquatic systems it settles into sediment and basically remains without further degradation, at least in the near term.

Hope all works out well.

edit - yeast degradation study was with picloram - text above edited.

This post was edited by TXEB on Wed, May 1, 13 at 12:30

    Bookmark   May 1, 2013 at 10:31AM
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toxcrusadr(Zone 6a - MO)

TX, you're an asset to this group with that kind of info at hand.

I wish we had a way to make Sticky threads on this forum. We should have one about this topic. There is a FAQ page, but I have no idea how to get something on it.

    Bookmark   May 1, 2013 at 10:34AM
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So I'll say it again because what TX posted is what I've basically read on this matter as well...

Several reputable composting operations have been affected by these long life herbicides. It is a problem, no one knows for sure how these products really biodegrade, the issue is still being studied and people have a right to be concerned.


    Bookmark   May 1, 2013 at 11:25AM
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tox - I would have had all the pertinent references to go with that summary (about a dozen decent articles, etc.) had it not been for two successive power glitches here yesterday morning that led to a loss of the open, unsaved file in which I was building the bib. PO'ed is not an adequate description of my state. Today, I am out of time, so regenerating the references will come slowly.

Lloyd - I agree with you upon the reality, and the need for concern. On the technical side regarding biodegradation, actually it is pretty well understood. That said, it doesn't help the composters keep it out of their feed-streams. At this point it comes down to recognition of the problem, practical strategies to deal with it, and integrity of the operators. As best I can tell, nobody is really ducking the issue once they get hit with the problem - it just typically takes that first hit to put in the controls to deal with it. Of course there is the usual finger pointing from all sides to the others because of the liability issues involved.

    Bookmark   May 1, 2013 at 11:57AM
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"no one knows for sure how these products really biodegrade"

No matter how many times you say this, it won't be true.

Not only do they know how they degrade, they know what chemicals/compounds they degrade into...and any further breakdown after that...and what mode of interaction will lead to them breaking down.

This is crucial information to anyone cropping anything...knowing what you can put into a field, how long it takes to degrade afterwards, and under what conditions.

It's part of the process of rolling out a herbicide. It's part of the process of getting your herbicide approved for the consumer market and whether it's a licensed controlled herbicide or an over-the-counter herbicide.

    Bookmark   May 1, 2013 at 2:38PM
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As TX wrote an excellent summary that basically mirrors what I've read I will just highlight some of his/her points:

suggesting some self-inhibition effect at higher soil concentrations

not definitive i.e. we don't know

Sunlight doesn't appear to affect the degradation.

Not definitive i.e. we don't know

apparently suppressed by higher levels of organic materials in soils

Not definitive i.e. we don't know

suggestion has been that the herbicides actually get tied up with organic matter

Not definitive i.e. we don't know

suggested that when the herbicides are introduced into composting via either manure or as residual in treated grasses or grain residues that biodegradation does not take place through the thermophilic stage

Not definitive i.e. we don't know

it may be microbe dependent or it may be that the herbicide molecules just aren't available by being tied up within the host matrix

Not definitive i.e. we don't know

but it isn't known.

self explanatory.

If any of this sounds like we know how this stuff degrades, then I guess I'm reading it incorrectly.


    Bookmark   May 1, 2013 at 3:22PM
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"If any of this sounds like we know how this stuff degrades, then I guess I'm reading it incorrectly."

You're not reading it just want it to be true that we have no idea how it degrades and what it degrades into. I have no idea what purpose this serves for you. We don't handle agriculture chemicals in this manner...there's a $100s-billion industry counting on it.

This point made by the person you're quoting seems to have been glossed over - "On the technical side regarding biodegradation, actually it is pretty well understood."

I don't know how to make it more clear that this is a key part of development and roll-out of a herbicide. It's like making a car without an speedometer and saying "Well, the consumer can just figure it out."

It is a key...crucial...important...known...part of rolling out any herbicide.

As far as how it will break down in a composting system vs a field...that's up in the air because of the lack of quality control in composting systems. There may only be a small amount of certain bacteria/yeasts/etc. or environmental conditions (heat/sunlight/moisture/etc.) that will break them down, but it's not only's known what they're broken down into via that process.

We know what breaks down herbicides...what mode of action...what they're broken down into. You're not going to find a herbicide on the market with unknown basic variables like's part of the approval process.

Seriously, this is part of introducing a herbicide in the marketplace. It's not "Wild-West" out there and if you can't tell a farmer how it's going to act/persist in their fields, they're not going to buy it. This is a major concern and very big's not a casual after-thought of choosing a herbicide.

This post was edited by nc-crn on Wed, May 1, 13 at 15:47

    Bookmark   May 1, 2013 at 3:38PM
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I'm sure they know the components of the herbicides and how they attach to each other and that they separate into the individual components again. I'm sure they know the herbicides do break down because I've read over and over again it breaks down in the soil.

But I'm also sure they don't know exactly what all the causes or inhibitions of this process in the soil or compost are. Why do some systems/soils degrade better/faster/worse/slower than others. If they did, they would have come out with a detailed step by step process for composting facilities to follow a long time ago and saved themselves a ton of grief. Instead, all we get are legal waivers and disclaimers.


    Bookmark   May 1, 2013 at 3:55PM
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nc is rght on this. There are a couple of issues here that tend to confuse the picture.

In the basic environment in which pesticide registrations are considered (soil, air, water), how these herbicides degrade, the time frame, the major influences, and the degradation products are quite well studied and known. EPA and the comparable European regulators would never grant a registration without that information.

What typically won't be known is, for soil or water borne microbial degradation, which microbes exactly are doing the work.

Composting is a different and new story. As a result of this whole issue that emerged in 2000/2001 in WA, a lot of study has been done. The compost environment is far more dynamic than soils or aquatic systems. By comparison, those are very stable and slow to change vs. what's going in in a composting environment. That variability stands to severely complicate what happens during composting. But today, what we basically know is what I represented earlier - the free herbicide basically degrades in mature compost as it does in soil. We also know that when the herbicide is sequestered within plant tissue it remains there and doesn't degrade. I between the input and the mature phase, when the herbicides appear as residue within plant tissue, or manure, is when we face the widely variable and complex processes that are composting, and hence a lot of yet unexplained relationships.

    Bookmark   May 1, 2013 at 3:59PM
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I think we cross-posted TX but when I read you state "hence a lot of yet unexplained relationships", I read, it's not known, which is exactly what I've said.


    Bookmark   May 1, 2013 at 4:09PM
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"If they did, they would have come out with a detailed step by step process for composting facilities to follow a long time ago and saved themselves a ton of grief."

The major issue here is how "Wild-West" the composting industry actually is.

On this very board...many times a year...practically many times a month we get users showing up with "I bought this compost and..." only to be followed by other users saying "That compost is crap./That compost isn't broken down./That compost isn't truly compost./etc."

There's no law or regulation in place that mandates compost actually has to be mixed properly, turned/churned and heated properly, or that the finished product actually has to be what one would consider a finished compost.

I have visited and advised on many commercial composting projects that are not doing it right. We've seen on this very board the result of scattered composting facilities all over the nation not doing it right.

The fact this seems to only happen once every few years rather than scattered all over the nation every year is a bit of a testament to those that "do enough" to degrade some of these compounds...even if they're still not selling finished compost products.

The fact so many of these issues seem to pop up in cooler/colder climate composting facilities leads me to believe that those up North need to pay a lot more attention to these issues, too. At this point I wouldn't advise anyone buy any cool/cold climate compost from any supplier without knowing that you're getting 100% fully broken down and processed compost. This has been an issue in Canada, too. It has sent one major private composting company in out of business a few years ago. Thistle is a major pest there and some of the same herbicides implicated in the original story prompting this post is/was part of the issue. That said...some other composting facilities seeing the exact same source materials did not have this issue.

    Bookmark   May 1, 2013 at 4:16PM
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Okay, give me the step by step procedures to compost that will guarantee, each and every time, that these herbicides will not survive.


    Bookmark   May 1, 2013 at 4:37PM
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"Okay, give me the step by step procedures to compost that will guarantee, each and every time, that these herbicides will not survive."

Every herbicide (or herbicide class/family) is breakdown specific, from time to how environmental/chemical/microbial conditions effect speeding up or slowing down this time.

Some stuff will break down with absolutely nothing just doesn't persist well and/or it's breakdown accelerators are common. Some stuff will not budge from the soil without proper breakdown inputs (be it environment, chemical, or microbial in nature).

If you're home and vary your source materials, get your green/brown ratios correct, get it hot enough, turn it enough, and fully "finish" your compost before adding it if you have a concern about crop sensitivity...that should prevent and/or take care of any issue.

Avoid road-side brush...avoid getting your greens/browns from a single source on either end unless you know it's "clean"...unless it's a minor addition, know what you're putting into your compost.

This post was edited by nc-crn on Wed, May 1, 13 at 17:02

    Bookmark   May 1, 2013 at 5:00PM
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Ya, that's what I thought.

Thanks anyways.


    Bookmark   May 1, 2013 at 5:07PM
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"Okay, give me the step by step procedures to compost that will guarantee, each and every time, that these herbicides will not survive. "

Lloyd, That can be practically done. It will entail that I specify your feedstock composition, your process (mixing/stacking/time/temp/moisture/aeration), the time, and the quality measures you will follow before releasing your compost. It's not difficult to do that, and I can design it for feedstocks that carry the maximum permissible amounts of the herbicides of concern permitted under regulatory law. It's basically a biochemical conversion process, and I can design and specify it to achieve the result you state. The chemical process industry does it all the time.

The difficulty for the composter begins with the very first step - the feedstock composition in municipal composting is widely variable. The next major hurdle is the last one - the industry does not utilize measures uniformly that assure the quality of the finished product.

Now, if you were a commercial or municipal composter could you live with that?

An article to the point linked below.

Here is a link that might be useful: Phytotoxicity factors and herbicide contamination in relation to compost quality management practices

    Bookmark   May 1, 2013 at 5:13PM
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Well, let me break it down for you another way.

Bentazon will break down just sitting's nearly undetectable in plant tissue or soil after 6 weeks whether you do anything to it or will break down faster in the presence of heat and proper microbes.

Paraquat will persist like a champ depending on concentration in soil and plant matter for months...even in the presence of proper breakdown microbes and environmental help, it's going to stick around for months...years if enough is there and it's not acted upon.

You can't treat every chemical like it's the there's some magic catch-all.

If you're at all interested in your compost, read what I said above your last post that you seem to think is useless information.

If you're not interested in the science, that doesn't make the science go away. If you're not interested in proper technique, that doesn't make improper technique valid.

Composting is a process of environmental, chemical, and microbial/fungal science in action. Some people can make compost that will devour chicken bones...some people can make compost that will leave chicken bones whole and untouched. There is a method to this madness...methods that takes the madness out of it.

    Bookmark   May 1, 2013 at 5:18PM
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I've seen that before TX. Lots of the information in that document seems to be based on guesses.

Reading the conclusion, the first two sentences use the word "may" and I love this "The presence of these residues should not be alarming if compost use for any particular application is not consistent with its overall properties." So basically it's saying that if the compost is contaminated with these herbicides, it's okay as long as the compost is not used on anything that that herbicide can affect. No kidding.


    Bookmark   May 1, 2013 at 5:33PM
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From Tex's last link (Phytotoxicity factors and herbicide contamination in relation to compost quality management practices)...and pretty much what's been said a few times in a "less scientific-sounding" manner...

"Since immature compost may contain sufficient degradation intermediates, soluble salts and other contaminants to cause phytotoxicity, particularly when applied at heavy rates, an effort must be made to distinguish confounding factors. Complete composting normally allows for the degradation of phytotoxic intermediates and synthetic compounds, such as herbicides, as well as allowing for leaching of salts. Absence of compost completeness standards within the compost industry leaves such factors to the guesswork of the end-user."

...bold for added emphesis

    Bookmark   May 1, 2013 at 5:37PM
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Lloyd - right, that doesn't help anyone. But given that's a reality the issue is how to get compost, reliably, where it's not an issue. The answer is in what I outlined, with the most important factor being the quality assurance done at the end. There isn't a whole lot of that done, yet, that will preclude "bad stuff" being released to an unsuspecting public.

This really is not much different than the evolution of many related technologies that are not well mature, and while composting is a very ancient process it is far from mature as an element in municipal solids waste disposal. Before these herbicides made that abundantly clear it wasn't considered one of the environmental fate routes that needed to be considered in the course of pesticide development and registration. I am pretty confident that has changed, and I would expect the next application package for registration of a new broadleaf herbicide to be used in ag crop protection of grasses as well as turf grass applications will need to address that very issue.

Just as a note in hindsight, what is kind of surprising is that this erupted ~ 2000, saw a lot of new concerns through ~ 2004, then largely went quiet without significant issue until last year when GMC got hit. Kind of weird.

    Bookmark   May 1, 2013 at 5:54PM
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arrrrg html broke

This post was edited by TXEB on Thu, May 2, 13 at 6:13

    Bookmark   May 2, 2013 at 3:12AM
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toxcrusadr(Zone 6a - MO)

Very interesting reading. I see very good points being made by all of you. I used to do those environmental fate studies for pesticide registrations at a commercial lab. Aerobic soil and aquatic degradation, anerobic aquatic, soil photolysis, activated sludge biodeg, etc. However, as complex as the testing regime is, I don't recall FIFRA requiring compostability studies. A lot can be inferred from the soil studies, though. Also that was years ago and it may have changed. If not they should think about it.

OK, some composting operations need to do a better job. IMHO the bottom line is, if a chemical is so much more sensitive than all the others to composting conditions that it's this easy to get batches of killer compost, you really have to wonder if it's a good idea to have that one out there.

    Bookmark   May 2, 2013 at 11:23AM
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It's a good point, but target plant selectivity is a hallmark of herbicide development. What everyone wants is high effectiveness with only the target plant, and no effect on the crop being protected.

For clopyralid, as an example, forage and grass hays are permitted a residual level of 500 ppm. We know that tomatoes are sensitive to levels of 30 ppb in the soil. If you couple that kind of effective selectivity with some environemtal persistence, then the stage gets set for someone, somewhere to have an issue.

edit - To illustrate the point -- if the half life for degradation were 30 days (about the average for clopyralid), and the soil level were 10 ppm, then by my calculation it would take ~9 months for that 10 ppm to decay to a level of While farmers did use to love the persistent aspect, many are now questioning the desirability because of how their options can get cut when faced with a need for crop rotation. That hit ND wheat farmers when scab became an issue.

I have heard anecdotally that WI dairy farmers in some areas are now prohibited from exporting their manures off-farm, and many are running out of places to keep the stuff. My suspicion is that market forces in the ag world may set a new direction before EPA and registration become a major issue.

This post was edited by TXEB on Thu, May 2, 13 at 12:44

    Bookmark   May 2, 2013 at 12:06PM
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I buy lots of composted manure from Wal-Mart and Lowes to improve my
Soil which is in some spots a little high in clay and/or sand.Usually the soil
Is easy to amend,drains well,and offers the range I require.I live in South AL
Close to the Florida line between two cypress swamps with mixed hardwoods
And horse/cattle pastures abt 1/2 mile up the road.There is no spraying or
Agricultural applications anywhere here close,and I don't use poisons.
I am just a Butterfly Gardener,but still to read all this abt the compost I buy
Bothers me! Is there no escape???LOL

    Bookmark   May 17, 2013 at 4:27PM
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All of our barley, wheat and canola are sprayed each year and we use the straw as bedding in the winter and sometimes use old manure in the gardens and have never noticed any problem with the plants, then again it is aged and rained and snowed on before it gets into the garden.

    Bookmark   May 24, 2013 at 1:22AM
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