Serving Kerr County with a Conscience

How to Kill Thistles

We have been experimenting with ways to kill thistles that avoid using herbicides. We have found that the 9% vinegar, available at HEB, kills them--but be sure to pour it on them BEFORE they bolt.
Kerr County has extremely severe infestations of this invasive species this year, since the drought and deer cleared the land of ground cover.  A thistle seed can last for seven years, waiting for just the right conditions for germination--so even if a person clears their land of thistles one year, he will still have six more years of thistles--and that is only if he does not have ANY further contamination.  The musk thistle problem is not only affecting residential lawns and commercial landscapes such as golf courses, cemeteries, and gardens, but the thistles are practically shutting down agriculture and ranching. Fields must be plowed, disced, and planted before thistles bloom, and even then the seeds thrive on the disturbed ground--farmers and ranchers are giving up, since the only thing a thistle-infested field is good for is development and urban sprawl. It can cost tens of thousands of dollars to keep your property musk-thistle-free.
In efforts to eradicate the thistles, entire ranches and farms are being sprayed with lethal doses of herbicides such as Round-Up and various forms of 2-4-D, which have a devastating effect upon the native wildlife, including birds, butterflies, and bees. Last summer I watched my neighbor spray his 100 acre range with 2-4-D--AFTER the thistles had already bloomed, and the bright pink flowers were covered with bees and butterflies.
The herbicides are entering stream and run-off watercourses and killing frogs and other riparian life--before making their way into the rivers and the waters people drink. Most municipal and governmental water authorities do not even test for herbicide contamination (neither the Upper Guadalupe River Authority nor the Headwaters Groundwater Conservation District in Kerr County test for herbicides.) 
This time of year Home Depot will sell millions of dollars worth of Round Up--and this potent herbicide is very ineffective in killing musk thistles. Usually two or more sprayings are required, Round Up will kill any small animal that comes in contact with it--such as lizards, snakes, birds, and frogs--and Round Up is also expensive.  Money spent on Round Up to control thistles is almost certainly thrown away.
Our local HEB will sell the 9% vinegar by the case. For my 100 acres, I just ordered 20 cases--about 2% of what I will eventually need-and I have been fighting thistles ever since I moved here, in 2003--NINE years ago. Government, agriculture, industry, environmental organizations, native plant gardeners, and the private sector need to team up NOW to make the public more aware of the threat that musk thistles pose to our quality of life in the Texas Hill Country.
For more information on Musk Thistles, click here.

Mary J. Matthews