I don't know what Plicotin is, and Google can't find it either. I referred
to Picloram which is persistent for over ten years. The Washington State
Dept. of Agriculture banned the use of Clopyralid on lawns in March, 2002,
to keep it from contaminating municipal and commercial compost. Clopyralid
was found to persist through the composting process and retain it's
herbicidal qualities for at least three years, according to a study at
Pennsylvania State University. A fact sheet prepared for the US Forest
Service, BLM and Bonneville Power Administration reports Clopyralid's
half-life in soil ranges from 15 to 287 days. Carbon dioxide is the only
degradation product they had identified. Dow Agro-Sciences, the
manufacturer, approves of label information reading "Do not use compost
containing grass clippings from turf treated with Confront (brand
containing Clopyralid) in the growing season of application."
A report from Washington State University in 2000 reported Clopyralid was
toxic in amounts of "10 parts per billion or less" and added that since the
chemical was generally safe for humans, most laboratories "do not routinely
measure either picloram or clopyralid below 50 ppb." WaSU was stuck with
47,000 yards of compost it couldn't sell because of trace amounts of
Clopyralid. I think you meant to cite WSU instead of UW, Ted. Margaret
Lauterbach
>
>I did some research into Clopyralid and Plicotin because we had a contract
>that used muni greenwaste. Theoretically, both are supposted to be broken
>down by soil bacteria. The ranges of breakdown are between 60 and 90
>days. The products containing these are represented as safe if the grass
>is grasscycled after mowing. In the report I read from UW, it seems that
>the muni greenwaste was, at the most, maturing on an average of 5
>weeks. They had too much and too much demand. The stuff was going out
>much faster than that if I recall correctly.
>
>So, when used at home and the clippings stay in the ground, supposedly,
>they breakdown in 60 - 90 days. This, of course, assumes that the soil
>biology hasen't been decimated through over feeding and salts and ??? But
>this is rarely the case. In Washington, I read where muni greenwaste
>operations had been suspended totally or that the public could not buy
>greenwaste from the operations or the greenwaste had to go to the landfill
>or a combination of the above depending on municipality.
>
>Clopyralid is toxic at 1ppb according to the UW report.
>
>Ted Peterson
>Earth-Wise/Spirit of the Earth
>
>
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Margaret L
Gardening in Intermountain West and Handicapped gardening
www.margaretlauterbach.com
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Received on Mon Mar 15 2004 - 10:43:05 EST