Puncturevine

Matthew Schuster

University of Idaho

Minidoka County Extension Educator

Puncturevine, also known as goatshead, Mexican sandbur, Texas sandbur, and tackweed, is a weed that is becoming increasingly more prevalent in the Mini-Cassia area.

We typically see this weed appear in early to late summer and growing in any open area; and depending on weather conditions this weed can grow into the fall. It is an annual that grows in a mat type of formation ½ to 5-feet in diameter. Leaves are hairy, divided into 4 to 8 pairs of leaflets, each about ¼ to ½-inch long and oval. Flowers are yellow and produce a bur-like spur.

It’s these bur-like fruits that result in punctured bicycle tires, cover our field borders, injure pets and livestock, and infest any bare spot around your house. The major problem with these burs is that they contain seeds. Therefore, every time you walk or drive your vehicle through a puncturevine patch, you end up transporting seeds to another area. In addition, the seed can remain dormant in the soil for 4 to 5 years.

Oregon State Univeristy

Managing punturevine requires a combination of tactics. First, minimize the spread. If you know you have a problem avoid walking or driving through infested areas if possible, and inspect your tires before moving to a new field. If you don’t transport the burs you won’t transport the seeds. I have heard of some individuals burning infested areas to burn off the sharp bur so that it cannot stick into tires or shoes. You may try this management strategy in areas you must travel through.

Second, if you use herbicides treat in a timely manner. Pre-emergence herbicides should be applied in accordance to the pesticide label recommendations and restrictions. If applied at the wrong time of year the herbicide may degrade before the seed germinates. If applying a post-emergence herbicide don’t wait until you can see flowers on the plant. The larger the plant gets the more difficult it will be to control. Also, once flowers are formed the plant may still produce seed even though a herbicide was applied. For herbicide recommendations contact your County Weed Superintendent, County Extension office, fieldman, or recommendations listed in the Pacific Northwest Weed Management Handbook (http://weeds.ippc.orst.edu/pnw/weeds).

Third, physically remove the plant if possible. If you can’t use a herbicide or it’s too late to apply one, physically remove the plant with a shovel, hoe, etc. Be sure not to leave the plant just lying there to dry up though. Depending on the maturity of the plant it still may produce seeds. It is always best to remove the plant and burn it.

Finally, plant a desirable grass in bare spots or field borders. Puncturevine is a very poor competitor with other plants. Therefore, if a perennial grass can be established along field or road borders, puncturvine will have a more difficult time establishing and you can still use a selective post-emergence herbicide that will control the puncturevine but not harm the grass. Contact the County Weed Superintendent about cost share funds and perennial grass variety options.

Puncturevine is not an easy weed to control but with persistence it is manageable. Keep these points in mind: minimize spread, apply herbicides in a timely manner or physically remove, don’t allow the weed to grow and produce flowers, and establish perennial grasses to compete against the weed.