This week’s article will focus on one of the more common weeds in Grant County, puncturevine. A native of Europe, puncturevine grows in dry, gravelly or sandy sites like roadsides, rangeland, orchards and edges of irrigated fields. In city areas, puncturevine is common in driveways and along the edges of sidewalks and lawns.
Puncturevine spreads out along the ground forming mats of stems. These branching stems can grow to six feet long. Leaves are opposite each other and have fine hairs. Flowers are yellow, small, five petaled and have short stalks. Burs or goatheads are spiny and hard when the plant matures.
Puncturevine is an annual weed and is easier to control early in the season. If puncturevine is allowed to go to seed, the seeds can germinate for up to five years. Since annuals produce only from seed (stop the seed, stop the weed), it is important to control this weed before seed set.
The seeds of puncturevine germinate in late spring and early summer. This noxious weed grows fast. Flowers may form within three weeks after germination. The sharp-spined burs are produced throughout the summer and are transported by sticking to tires, shoes and even the fur of our pets. Puncturevine burs can easily flatten a bicycle tire.
Since puncturevine reproduces by seed, controlling plants prior to seed germination is critical to prevent further seeding. When you see a flower on a weed, the seeds are not far behind. Pre-emergent herbicides work well for annual plants, but have to be applied to the soil ahead of seed germination. Remember that pre-emergent herbicides will affect desirable plant seeds as well, so caution is recommended.
Puncturevine can also be hand pulled or controlled by hoeing. This must be done prior to seed formation to be effective. If plants already have burs, pull and bag the plant material and try to gather as many of the spiny burs from the ground as you can.
There are herbicides available that will effectively control puncturevine. Make sure the herbicide you are using has puncturevine listed on the product label. This will better ensure a successful spray application and control of the target weed. As always, please read all label instructions carefully before applying any herbicide.