What do Canada Thistle and gardening have to do with each other? Well, maybe more than you think!
Like many ranches in western South Dakota, we have some Canada Thistle too. We have been trying very hard to control the thistles with mechanical methods (i.e. mowing, cutting, etc.). But this year, there are more thistle plants. Many more. I'm not sure why there are so many more this year. Maybe it's because of the additional moisture, or maybe I missed cutting one or more plants that went to seed last year. So, we are doing some research and trying to become more informed on the topic in an attempt to control the noxious weed. I've visited with neighbors, friends, the Soil Conservation folks, the Meade County weed control specialist, and a couple salesmen at Warne Chemical (a Herbicide distributor in Rapid City). I've also read about the weed in several noxious weed books and studied many web sites. I even downloaded a Noxious Weed application to my iPhone.
Anyhow, in our quest to understand the issue, Michelle came across a very interesting article published by the North Carolina Cooperative Extension. The article is titled "Herbicide Carryover in Hay, Manure, Compost, and Grass Clippings", and was published in 2010. This is a MUST READ for any gardener that uses hay mulch, manure, compost, or grass clipping on their garden.
Here is the URL to the original article:
http://www.ces.ncsu.edu/fletcher/programs/ncorganic/special-pubs/herbicide_carryover.pdf
Target Audience:
- Hay Producers
- Livestock Owners
- Farmers
- Home Gardeners
The article explains the potential danger and damage that can occur to a vegetable garden by applying manure, compost, or grass clippings that may un-knowingly still have herbicide chemicals that are active.
Primary Points:
- Use of manure, compost, or grass clipping applied to a garden may still have active herbicide chemicals that can damage gardens.
- List of herbicides of concern:
- 2,4-D based products
- products that contain picloram, clopyralid, or aminopyralid
- List of crops known to be sensitive to herbicide carryover
- How to prevent herbicide damage to non-target plants
- How to test for the presence of herbicides
- Complete herbicide breakdown and deactivation can take several years in some situations.
- Herbicide is applied to a hay field to control Canada Thistle or other noxious weeds
- Hay is later cut, baled, and used for livestock feed (maybe sold to another rancher)
- Cattle eat the hay and produce manure
- Rancher moves manure (from barns, cattle shelters, feel lots, etc.) to storage/compost pile
- Home gardener gets manure and applies it to a vegetable garden
- Herbicide is applied to a lawn to control weeds
- Grass clippings from the lawn are stored/composted (i.e. city or private compost program, etc.)
- Home gardener gets compost and applies it to a vegetable garden
- A potential and common danger occurs when the herbicide chemicals are transferred from one form to another (i.e. hay, grass clippings, cattle, manure, compost, etc.), and from one person to another (i.e. hay producer to rancher, rancher to gardener, etc.), and knowledge of the original herbicide application facts are lost.
- Many people who apply herbicides have a mis-understanding of residue break-down. I've heard from several people (i.e. neighbors, friends, etc.) statements like "wait 48 hours after spraying, then it is completely safe". Safe for what? Walking thru? Hmmm...
- If you are a gardener and add hay mulch, manure, compost, or grass clipping to your garden, then do your homework first! Know where it came from -- all the way back!
Rick Grosek
Bear Butte Gardens
Rick@BearButteGardens.com
http://www.bearbuttegardens.com/
