Welcome back to the second installment of “Weed of the Week”. This post is going to be all about Puncturevine.
Puncturevine (Tribulus terrestris) is another weed that you, unfortunately, may be familiar with if you have spent very much time in Eastern Oregon, or at Cottonwood Canyon state park.
There are many different names for Puncturevine around the world. Growing up with an Eastern Oregon vocabulary I have always called the weed Goat heads. Some other names from around the world are bindii, bullhead, caltrop, small caltrops, cat’s-head, devil’s eyelashes, devil’s-thorn, devil’s-weed and one my favorites “Destroyer of bicycle tires”.
Puncturevine is native to the Mediterranean region and may have been brought to the United States via contaminated sheep’s wool imported from the region. Puncturevine is now widely distributed throughout the United States.
Puncturevine is a summer annual and and grows low to the ground radiating from a central crown. The plant usually starts to appear in the early summer at Cottonwood Canyon once temperatures start to rise into the 80s and they continue growing throughout the summer. Puncturevine thrives in disturbed soil and can grow in very dry and hot climates. Plants can grow upwards of five feet in diameter and each plant can produce 200 to 5,000 seeds per growing season. Puncturvine seeds can stay viable for up to 5 years.
Some of the negative effects of puncturevine include quickly taking over an open area and out competing desirable plants, the seeds can cause injury to the mouths and digestive tracts of grazing animals, and the plants can be very detrimental to recreational areas by causing injury to pedestrians as well as puncturing bicycle tires.
*These control methods are not exhaustive and are for information only
Mechanical- Pulling the puncturevine plant can be highly effective especially in small infestations. The plant solely reproduces by seed, so by pulling the plant before it goes to seed you can effectively stop reproduction. We have found that using the back of a claw hammer and pulling directly at the crown of the plant works extremely well and saves your hand from being stabbed if the plant has gone to seed already. Removing seeds from an area can greatly reduce and infestation, in small areas using a carpet to push down into the ground can pick up loose seeds. Mowing is not effective due to the prostrate growth pattern. Cultivation can help if done before seed production and combined with planting of desirable plants.
Biological- There are two puncturvine weevils Microlarinus lareynii and Microlarinus lypriformis that are being used to help control infestations. There has been varying success using the seed weevil in Oregon. There was some success in Umatilla County in the early 2010s. One issue is that the weevils do not establish well in areas with cold winters. See here for more info.
Chemical- For larger infestations, chemical control can be an effective control measure. Puncturevine is quite susceptible to herbicides especially when the plant is young. Applying herbicide before the plants have gone to seed is critical in reducing the future seed bank. In areas where there isn’t a worry of harming desirable plants glyphosate, glufosinate, or other non-selective herbicides may work well. For a selective herbicide in an area of lawn or with desirable grasses 2,4-D or Dicamba is very effective as a post-emergent herbicide. Herbicides with the active ingredient chlorsulfuron, such as Telar XP, can be used as a pre-emergent and can help keep seeds from germinating. As always with any chemical control it is important to read and follow the product label and to make sure you have the proper training and licensing to apply herbicides.
Nobody asked for it, but here it is, Weed of the week poem version 2.0 Bonus points if you can guess what song was in my head when writing the new poem.
Puncturevine, enemy of mine
When you gonna stop growin’?
Puncturevine, you got me misaligned
anything to get you slowin’
You’re a disgrace, to this place
That we like to call home
Up our pace, to win the race
Trying not to let you roam
There is no doubt, even in a drought
That you will come in strong
Stepping on you makes us shout
But we are coming along
Oh Puncturevine, devil entwined
Gotta get rid of you
Puncturevine you’re outta time
Gonna be the last thing I do
Weed Control in Natural Areas in the Western United States
University of California
Oregon Department of Agriculture