Harvesting ditch hay (grass and legumes growing alongside the roadways) is a common practice, especially in western and northwestern Minnesota and provides several livestock owners with suitable forage for beef cattle, dairy heifers and horses. Picloram (commonly sold as Tordon and Grazon) and clopyralid (commonly sold as Stinger, Curtail and Transline) are commonly used by highway departments to control unwanted broadleaf weeds, especially thistles, along roadways.

When animals are fed ditch hay that has been treated with either picloram or clopyralid, these chemicals pass through the animal ending up in the manure. Manure application to agriculture production fields is a beneficial and common practice. However, if sensitive crops (soybeans, lentils, peas, legumes, potatoes, tomatoes or peppers) are planted in fields where contaminated manure has been applied, injury or crop death can occur.

Both picloram and clopyralid carry important precautions that ditch hay harvesters and feeders need to be aware of:

1. manure and urine containing these herbicides may cause injury to sensitive broadleaf plants;
2. plant material containing these products should not be used in compost;
3. Picloram and clopyralid are persistent and mobile in the soil, readily absorbed and translocated throughout the plant, and remain chemically stable and intact in plants.

Because of these characteristics, both products 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 this issue insist that relying solely on herbicide label restrictions is not enough and recommend soil analysis to detect clopyralid and picloram.

Composting or storing manure that contains clopyralid and picloram may not speed-up herbicide degradation as these products do not break down quickly in compost. Currently, it is believed that clopyralid can remain in manure, forage/feedstuffs or compost for several years. These data suggest that composting contaminated manure is not a solution for this problem. However, you can spread contaminated manure/compost on fields that will be planted into grass crops (i.e. corn, small grains, or sorghum sudan forage).

Better awareness and communication is needed between local and state highway departments and farmers harvesting, feeding and selling ditch hay. Farmers need a permit to hay highway areas that MN Department of Transportation (MN DOT) owns, however, permits are not needed on roadways where only an easement is owned by MN DOT. The permit is free, and by contacting MN DOT and obtaining the permit, the farmer will be notified of any cutting restrictions due to herbicide use, wildlife habitat designation and/or calendar date restrictions.

For contact information regarding the permit, visit:

http://www.dot.state.mn.us/

Roadways owned by county and local governments have their own regulations, and farmers should contact their County or Township to obtain any cutting restriction information prior to harvest.

For a list of laboratories that test forage and soil samples for picloram and clopyralid visit:

http://weeds.cropsci.uiuc.edu/newsletter/misc articles/labanalysis.htm

To learn more about harvesting and feeding ditch hay, visit:

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

Additional Information:

Cox, C. 1998. Picloram, Herbicide Fact Sheet. Journal of Pesticide Reform, 18:1 pages 13-20. http://www.pesticide.org/picloram.pdf

Cox, C. 1998. Clopyralid, Herbicide Fact Sheet. Journal of Pesticide Reform, 18:4 pages 15-19. http://www.pesticide.org/clopyralid.pdf