There is one invasive weed that puts the brakes on bicycling in Idaho more than any other. It punctures bike tires, sticks to the soles of shoes and causes our four-legged friends pain when they get it in their paws.
We call it goathead but it also goes by puncture vine, devil’s weed and devil’s thorn among others. Tribulus terrestris is an annual, meaning the plant dies each year but comes back through seeds. The plant itself can be quite pretty and is a green leafy vine that can spread from a center root up to four feet. It has dainty yellow flowers which then turn into seeds. The seeds are the culprit and each goathead has sharp thorns and breaks into five individual seeds which propagate the next generation.
It is reported that seeds can live for up to 7 years in the soil, waiting for the right conditions to germinate. Eradicating goathead means being persistent and goathead control can be a lengthy and labor-intensive process. Pull it as soon as it emerges and especially before the seeds form. Try to sweep up as many seeds as possible or pull an old rug or carpet remnant over the area to collect the burs. Stop the spread by checking tires, shoes and pets after each outing. If you find a goathead throw it in the trash not onto the ground. Chemical control can also be effective but be sure to follow all directions on the bottle and be mindful of when and where you are using this method.
Goathead prefers hot, sunny areas where it can establish itself without competing with other plants. It is often found along roads and sidewalks, abandoned lots, canal banks and other areas that might not be maintained.
How does goathead affect safe routes to schools? Students traveling to and from school in areas where goathead is prevalent experience more flat tires. This can make them late for school, put their bike out of commission until the tire is fixed and can require quite an investment in time and money by patching or buying and installing new tubes. If a student’s shoes have thin soles, the thorns can pierce through the shoe into their feet. Students also become unsuspecting spreaders of goathead, helping it move to new areas not already affected.
What can you do?
- Pull the goathead plant before seeds form.
- Try to sweep up as many seeds as possible.
- Inspect tires, shoes, clothing, and pets for burs after each outing.
- Throw goathead burs in the trash rather than on the ground.
- Work with government agencies or groups to tackle patches of goathead near sidewalks and trails.
- Commit to clearing an area of goathead for several years in a row to prevent new growth.
For more information visit the Boise State University webpage Boise’s Public Enemy #1: the Goathead puncturevine.