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Anamosa, IA BPIowegian@aol.com

I visited a friend's patch today and he showed me his big problem. Nearly everything in his garden, from pumpkins to muskmelons to weeds was curling up. Last year he has sprayed his small horse pasture with Grazon to kill thistles and other weeds. The horses left some of their droppings in the barn, and he gave his patch a good shot of that. It seems that the herbicide went throught the horses digestive tract and into the manure. So, if you get manure from animals that are raised on pastures that may have been treated with herbicides, be very careful.

6/14/2006 10:30:15 PM

Ctpumpkin@optonline.net

The guy didn't read the leabel on the herbicide?

6/15/2006 3:49:56 PM

Carrollton, Ga.

Steve,
I remember a post I think you made several years ago about grass clippings that had been treated with weed killers. It said you could pile them up and after a year that mulch would be ok for the patch. Could I pile up manure that had been from a pasture treated with grazon and it be ok for the patch after a year?
We can get manure from our local cattle sales barn but I have been afraid to get it for this very reason.


Thank you,
Doug Adams

6/15/2006 4:53:34 PM

Ctpumpkin@optonline.net

From the Grazon label:

"Do not use manure from animals grazing treated areas on land used for growing broadleaf crops, ornamentals, orchards or other susceptible, desirable plants. Manure may contain enough picloram to cause injury to susceptible plants."

Ditch hay is another source of potential contamination since Tordon (picloram) is often used on road sides to control unwanted trees.

The lawn herbicide you remember contained the active ingredient "clopyralid" which is still on the market but not for use on residential lawns. In clopyralid's case, the clippings had to compost for 9+ months to let the herbicide degrade.

6/15/2006 8:33:08 PM

Ctpumpkin@optonline.net

You might find this clip helpful:

Both herbicides are persistent and mobile in the soil, are readily absorbed and translocated throughout the plant, and remain chemically stable and intact in plants. Picloram and clopyralid have been detected in the groundwater, but only picloram has been detected in groundwater in Minnesota . Picloram has a field half-life (the time required for one-half of the herbicide to break down) of 20 to 300 days with an estimated average of 90 days . Clopyralid has a field half-life averaging 40 days, with a range of 12 to 70 days, and can persist in the soil for up to 14 months depending on soil type, climate and other factors. The label for Curtail (clopyralid and 2,4-D) cautions that in drier areas of reduced microbial activity, sensitive crops may be injured for up to four years after application. Because of these characteristics, products containing clopyralid and picloram carry a crop rotation restriction of 18 months for sensitive broadleaf crops, or approximately two growing seasons in Minnesota . However, researchers in other states who have dealt with treated ditch hay issues insist that relying solely on herbicide label restrictions is not enough to protect sensitive crops treated with contaminated manure or compost. They recommend soil analysis to detect clopyralid and picloram prior to planting sensitive crops.

http://www.extension.umn.edu/cropenews/2005/05MNCN43.htm

6/15/2006 8:33:37 PM

Ctpumpkin@optonline.net

Grazon label:

http://www.cdms.net/ldat/ld0B1000.pdf

6/15/2006 8:34:16 PM

Ctpumpkin@optonline.net

He might try activated charcoal if he has immediate need of the land. Otherwise he has to wait it out.

I wish there was better news.

6/15/2006 8:36:26 PM