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Controlling Common Tansy with Sheep
By Kimberly McConnaghy
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Common tansy (Tancetum vulgare), also referred to as golden buttons and garden tansy, is a perennial herb in the sunflower family. It is a native of Europe and has been used for medicinal purposes or as an ornamental plant. Like many other non-native ornamentals, Common tansy has escaped into the natural landscape. It has invaded along roadsides, wetlands, riparian corridors and ditch banks. This plant threatens ecological health, as well as the economic value, of pastures, riparian areas and cropland through the reduction of livestock forage, species diversity and irrigation water.
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There has been limited research on control of common tansy. And most literature states, that grazing is not a control option because livestock find it unpalatable. However, I have found that sheep will consume common tansy and that multiple grazings do impact its ability to compete with other plant species.
The idea for this project developed in the summer of 2003. I had put my flock of Katahdin sheep in the neighbor’s pasture to graze spotted knapweed and to my horror they grazed the common tansy. After finding Common Tansy in the first pasture, no matter which pasture I placed them in, the sheep looked directly for and consumed the Common Tansy before foraging on any other plant species. To say the least, I was a bit concerned about the sheep eating the Common Tansy as I knew it to have an abortive property. So, I started doing some research on the internet and at the local library but found no information on the grazing of or the toxicity levels of common tansy. Then, I turned to my county extension agent who suggested the Western SARE program which awards grant monies for agricultural research.
The common tansy project was conducted at two ranch locations/sites in 2004, 2005 and 2006. (In 2004, we conducted our trial run for the SARE grant application, so only photographic data is available.) The common tansy sites were enclosed with electric net fencing and the sheep grazed each site until 90-100% of the common tansy had been consumed. Each site was grazed in the spring and then again when the majority of the plant stems had immature flower heads forming. The county extension agent and I gathered percent cover, stem height and # of stems present at designated plots, each spring. Stem height readings were also gathered at the plots, approximately every 10 days after the sheep left each site.
The plot data portrays a slight impact on the common tansy infestation from year to year however; it does show a significant reduction in biomass from grazing to grazing.
The project also included a look at the toxins in common tansy. The downfall is that there is no good information on them. I had wanted an analysis completed on plant samples; however the analysis could only look for known chemical compounds. So instead, blood samples were collected from the same ten ewes and tested for toxins. The blood samples were collected prior to grazing, post-grazing and ten days post-grazing. The toxin tests were completed at the University of Idaho Caine Veterinary Teaching Center and the results showed no significant changes in the ewes’ blood chemistry. I also monitored the sheep for symptoms of photo toxicity and none occurred.
I think that this project depicts a ray of hope for those producers who have been saddled with this unwanted pest. It shows that timed grazing of common tansy for several seasons leads to reduction of its biomass. And with that, herbicide applications become more effective and economical.
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Suggestions for Others; In other words, Learn From My Frustrations:
For those producers who would like to implement this project on their own operations, I have a few suggestions. The first is to consider the site in regards to the possible wildlife activity that occurs there. Deer, elk and moose can wreck a good project, along with the electric net fence. In areas of high wildlife traffic, it might be a good idea to move the sheep to a night pen and open the electric fence along used game trails.
Another suggestion is to consider the sheep species and their habits. Some sheep breeds flock and herd better than others. It is best to train the sheep to the electric netting inside a secure corral system prior to a project.
The last recommendation is to use plenty of supplements and to have fresh water for the sheep. My flock of ewes will stop consuming Common Tansy if their dietary needs are not being met. The important fact to consider is that Common Tansy only has 4% crude protein where as a grass plant has around 8% crude protein. Water is essential in the flushing of the fibrous material through the sheep’s digestive system.
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Special Thanks To:
Demoin McConnaghy(husband)
Western SARE Program
Shannon Williams
Bill Andrews
Dave McFarland
Katie Hoffman
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Below is project data. Click on each item to display its infomation.
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Below are some pictures of the project. Click on each image to enlarge and to see details.
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