Herbicide Tainted Compost Ruins Crops
Subject: Herbicide Tainted Compost Ruins Crops
Date: Wed, 13 Mar 2002 08:53:22 -0500
From: Stephen Tvedten <steve@getipm.com>
Organization: Get Set Inc. (http://www.getipm.com/)
To: Paul Helliker <phelliker@cdpr.ca.gov>
Director, State
of California, Department of Pesticide Regulation
cc: Christine Whitman whitman.christine@epa.gov
Dear Mr. Helliker, I thought you might like to read an article entitled: Herbicide Tainted Compost Ruins Crops. This article originally appeared in the publication In Good Tilth, Feb. 15, 2002, v.13, no. 1, a publication of Oregon Tilth. Website: www.tilth.org. Subscriptions, free with Oregon Tilth membership, are $25/year ($35 outside US). Reproduced with permission.
Art Biggert has been farming organically for 10 years on his Ocean Sky farm in Washington. He says cover cropping and composting are the left and right arms of his soil fertility program, and he usually adds seven tons of finished compost per acre as a soil conditioner or mulch. Every two years, he documents improvements in his soil health with a comprehensive soil analysis.
In June of 2001, he was shocked to see what appeared to be herbicide damage on one of his pole bean cultivars and his entire tomato crop. Ultimately, Biggert was able to trace the damage to his compost, which showed a concentration of three parts per billion (ppb) of clopyralid, an herbicide. Though branded clopyralid products are sold with a warning that sprayed materials should not be composted, only the original herbicide applicator ever sees the label. Once the material is passed on, say as hay or straw for livestock feed or bedding, there is no method to ensure that the warning is heeded.
Clopyralid is a persistent herbicide and does not break down through digestion.
Livestock eating sprayed hay will urinate clopyralid. Stable sweepings that Biggert composted contaminated his soil. Now he worries that his organic certification may be jeopar-dized too. Clopyralid does not undergo microbial breakdown very quickly during composting, and since material mass generally decreases by half during composting, the concentration of clopyralid can actually increase.
Nearly all hay and wheat crops grown in Eastern Washington are at least spot-sprayed with clopyralid to fight Canadian thistles and other grain crop pests. There is no way to differentiate a bale of hay treated with clopyralid from one that was not.
Confront, a popular herbicide containing clopyralid, is also used by nearly every major commercial lawn care service in Eastern Washington. Confront is used on laws to control dandelions, clover and other broadleaf plants. It was introduced in
1989 to replace herbicides that required multiple applications. Clopyralid also is registered in a number of formulations used on cereals, grass hay, sugar beets, mint, asparagus, strawberry, blueberry and Christmas trees.
Art Biggert's problem, though personally devastat-ing, was just one small example of the damage that contaminated compost has caused in the state of Washington.
Thirty-seven states have mandates that prohibit the dumping of green waste in landfills. Many of those states have developed regional composting facilities to take in yard waste and organic materi-als from the public and create a saleable compost product. Washington has about 30 licensed public and private composting facilities.
Herbicide-tainted compost from such facilities has caused over a half million dollars worth of damage in the state in the last two years.
The Spokane Regional Compost Facility in Colbert, Washington, opened in 1993 and, until recently, operated an open windrow site, processing 25,000 tons of compost a year. In 2000, local growers noted that tomatoes grown in containers with compost from the Colbert facility were inexplicably dying. The problem was traced back to lawn clippings that were taken to transfer stations and later composted at the Colbert facility. Samples of the compost taken in January, 2001 (nine months after the problem surfaced), showed clopyralid residues of 31 to 75 ppb.
After an investigation by the Washington Department of Agriculture, the sale of compost from the facility was halted. Forty-seven thousand cubic yards of compost, a year's worth, was deemed unusable. At $6 to $12 a cubic yard for finished compost, the facility lost $282,000.
A limited amount of the compost from the 1999-2000 season was ulti-mately sold to landscapers and other wholesalers, with the understanding that it could be used only on turf, not gardens. Purchasers had to sign a waiver and name the city on their insurance policy. The Spokane Regional Solid Waste System has settled a few claims for damage from the compost for an undisclosed sum.
Instead of curtailing herbicide use, the city first attempted to resolve the problem with a different composting method. In the fall of 2000, Spokane--based Norcal took over operation of the Colbert facility and started producing compost using an Ag-Bag aerated windrow system. It was hoped that changing the composting method would lead to better degradation of the herbi-cide. Norcal sampled the bagged material in March, 2001, and clopyralid was present at 57 to 67 ppb. In May, 2001, the finished compost failed a bioassay test. Contamination levels have now been tested at 73 to 80 ppb.
In April, 2001, the city and Spokane County asked Dow Agrosciences, the producer of the herbicide, to voluntarily, temporarily halt distribution of clopyralid in the Spokane area, and Dow agreed to do so for residential uses.
Washington State University (WSU), 80 miles south of Spokane in Pullman, Washington, produces 25,000 cubic yards of compost a year from animal manure and bedding collected from the university's farm and research facilities. The product is sold to nurser-ies in Eastern Washington and northern Idaho as straight compost and is also blended by nurseries in a 50/50 com-post/soil mix.
In 2000, WSU found traces of picloram, a compound closely related to clopyralid, in its compost. Picloram is used to control weeds in agricultural and industrial applications, on pastures, rangeland, railroads and power lines. The source of contamination was eventually traced to a pasture sprayed with Tordon-lOl.
The pasture was harvested for hay, which was fed to livestock. The manure and bedding taken to the WSU composting facility carried the picloram with it. In spring, 2001, compost from WSU's windrow system was also found to contain clopyralid in concentrations as high as 200 ppb.
WSU has begun a bioassay test program for soils suspected of being contaminated by the compost. Remediation strategies such as frequent watering and cover crops are being promulgated to facilitate breakdown of the chemicals. WSU has provided activated charcoal to homeowners as a means of reducing or eliminating the damage. In some cases, where high amounts of compost were applied in 2000, sensitive plants were still affected in 2001. The community gardens in Moscow, Idaho, the Koppel Farm Com-munity Garden in Pullman and some of WSU's own plant and soil scientists' home gardens were among those affected. WSU has not sold any compost for the past two years.
The cost from the loss of revenue, claims, bioassay and analytical testing and additional labor has totaled about $250,000.
Both clopyralid and piclorarn are growth-regulator type herbicides. They work by mimicking plant growth hormones called auxins, causing the plant to grow abnormally.
They are both water soluble and mobile in soil. According to the EPA, field studies have shown clopyralid to be persistent as long as 14 months after application. WSU's tests demonstrate that persistence continues longer than 18 months. Although plants may appear normal, the loss of apical dominance usually prevents fruit set.
Some leaves that are supposed to be compound become single leaves. Side shoots may develop where they should not. In legumes, cupping is a typical symptom and trifoliate leaves fail to develop. Effects on solanaceous plants can be seen at levels of 10 ppb or less. According to Dow's literature, this is roughly 100 times lower than the tolerance allowed on asparagus, 50,000 times lower than the tolerance allowed on grasses and 300 times lower than that allowed on barley grain. Flowers such as safflower, sunflowers, mari-golds, pansies and petunias are also susceptible to these herbicides in extremely low doses.
Most laborato-ries do not routinely measure either picloram or clopyralid below 50 ppb. At WSU, an initial series of analytical tests of its compost did not reveal contamina-tion from any herbicides because the allowable tolerance was set too high.
Herbicides in the pyridine car-boxylic acid group, such as clopyralid. break down very slowly, especially during composting.
Clopyralid is also a likely water contaminant. Resistant to bioremediation, it may move from groundwater into streams and rivers unchanged. In 1998, despite clopyralid's relatively low level of use at the time, a US Geological Survey found it in two of 20 river basins studied.
The International Organization for Biological Control has found clopyralid to be toxic to three species of beneficial insects. Ladybug, pirate bug and lacew-ing populations are all damaged by clopyralid application and volatilization.
Composting facilities in other regions haven't had the same problems in part because they are in areas that don't seem to use as much of the herbicide, according to Dennis Hem, the director of the Spokane Regional Solid Waste System, which operates the Colbert, Washington, composting facility. In Eastern Washington in 2000, 1,367 gallons of Confront were used, versus 477 gallons in Western Washington.
Public utilities in Washington and Oregon have asked the EPA to recon-sider its criteria for registration and re--registration of herbicides to include the ultimate end use of urban yard trim-mings, food scraps and agricultural wastes. They request that residual herbicides be tested in the normal 60- to 90-day composting cycle to assure that no residues remain.
Norcal, the operator of the Spokane facility, is working with Dow on a research project seeking a way to break down clopyralid in compost. The scope of work includes testing residues in grass from test plots at different inter-vals after spraying, as well as compost-ing in a laboratory setting under a variety of conditions.
A bioassay is the most economical means to test for persistent herbicides if you suspect that your compost is contaminated. Mix 15 to 25 percent finished compost with any known clean soil in four-inch pots, and plant your favorite pea or bean.
Make several test samples. Herbicide damage will show up on the second set of true leaves.
The leaves will appear cupped and slightly twisted. A distortion of the stem appears because the plant will lose its apical dominance at the junction of the second leaf, if it survives. If you get no growth, the compost was most likely not finished.
For more information, contact Cliff Weed, Washington State Department of Agriculture, Pesticide Management Division, POB 42589, Olympia, WA 98504-2589; (360) 902-2040, (360) 902-2093 (fax); cweed@agr.wa.gov. Dow Agrosciences, LLC9330, Zionsville Road, Indianapolis, IN 46268- 105430.
-Compiled By Lacey Phillabaum, Editor, In Good Tilth 541-729-5673 lacey@tilth.org From: Chrysalis Farm at Tolstoy An Organic Micro-farm Practicing Sustainable Agriculture 33495 Mill Canyon Rd. Davenport, WA 99122 (509) 725-0610 FAX: (509) 695-6422 www.thefutureisorganic.net bright@famrc.org
Well Mr. Helliker, It is amazing to see the problems your "registered" POISONS cause.
Respectfully, Stephen L. Tvedten
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