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The Trouble With Tribulus Terrestris L.

Goatheads make biking, walking dangerous sports


Whether you call it a bullhead, Texas sandbur or a caltrop, it's all the same: Tribulus terrestris L., or the thorny little weed known around these parts as the goathead. Are there worse noxious weeds out there? Of course. But the costliness when goatheads shred your bike tires, or have to be pulled out of your dog's paws at the vet, make them a particularly vile little nemesis. Few things cause more cursing when stepped on barefoot besides a goathead (except maybe Legos, jacks, or those hard, plastic toys that come in Happy Meals). Goatheads are Mother Nature's own special little way of saying, "Ha ha."

There are, thankfully, products on the market to protect bike tires. There are even special little doggy paw mitts to protect Fido's fragile feet. But even those armed with purchased products have found that no cure is 100 percent foolproof. Is there any redeeming quality in these sticky little nuisances that cause injury, flat tires and general aggravation?

Goatheads are taprooted herbacious perennial plants that grow all over the world. From North America, southern Europe, southern Asia, Africa and northern Australia the plant is widely naturalized

But surely, the goathead plant would be expected to have some medicinal or naturopathic use. It does.

It has been reported that the seeds have been used in homicidal weapons in southern Africa. Murderers smear the seeds with the poisonous juice of a shrub called Acokanthera venenata and place the lethal combo where victims sleep, producing toxic cardio glycosides strong enough to cause death. Certain tribes also use it to coat arrowheads, making their weapons doubly lethal.

In the Indian ayurveda—an ancient system of health-care practice used most commonly in India, Nepal and Sri Lanka—Tribulus terrestris is used as an aphrodisiac, which just goes to show that one man's toxin is another man's tonic.

If the idea of mixing goatheads in with your morning smoothie to increase libido still isn't enough to make you change your mind about their usefulness, there are several known methods of eradication, some more effective than others.

The most common method is chemical warfare. Crickett Rudd at FarWest Landscape and Garden Center in Boise says the best way to deal with the adult goatheads that you're seeing now (and that you're probably picking up in your shoes or tires), is just to pull them. "They're in the process of dying because they're an annual and only live that year. You can use Roundup or something on them now, but if you don't want them to come back next year, you have to use a pre-emergent very early next spring, probably at the end of February. Wherever you have goatheads now, put down the pre-emergent and it'll kill them off before they become adult plants."

There are also natural methods of eradication. Two different weevils were introduced into the United States back in 1961 as biocontrol agents. Both species of weevils are available for purchase, but unfortunately, weevils collected from other areas may not survive in Boise and are therefore, not widely recommended. As it turns out, in cold climates, weevils really do wobble and then fall down and die. Weevils prefer warmer climates with mild winters, making them a great method of treatment for Texans, but not so much for Boiseans.

For bicyclists, the best fuel against flats is a product called Slime. Bill Davis at Idaho Mountain Touring says that thousands of flat tires come through their shop this time of year, courtesy of goatheads.

Davis recommends Slime as the best method of fixing your flat.

"Slime is like paper pulp, and it dries on the inside of the tube and creates a plug. It costs $12 for both tires to be filled. It's the easiest, best solution. There are other options, like thorn-resistant tires and tubes, [but] they're more difficult to install and they won't work quite as well. They're preventative, but with Slime you can fix an already damaged tube."

Idaho Mountain Touring also carries tire liners, which are strips of plastic that are placed between the tube and the inside of the tire to help protect against goatheads, but Davis says they are not 100 percent effective. "If you're really worried about goatheads, your best bet is to do a combination of Slime and tire liners, or Slime and a thorn resistant tire." The shop also carries dog booties to help keep Fido's feet goathead free as well.

So while naturopaths may find goatheads useful, those of us not willing to ingest them don't. Maybe they truly are Mother Nature gone awry. Nuisance, thy name is Goathead. Or Puncture Vine. Or Caltrop.

Whatever your vernacular, Tribulus terrestris is the same: a major pain in the pads.