Mechanical control is very effective for controlling this troublesome plant. Always pull up by the root and if you are dealing with large plants roll them to prevent scattering seed. Bag them and dispose to stop the spread. Intrinsic Organics employees in Weiser, ID are using this method to deal with their puncturevine problem.
Pictured is Bruce Cox displaying one of the larger plants, last count from the crew was 7-40 gallon drums filled with plants.
Facts: Each puncturevine burr contains 5 nutlets, 3-5 seeds per nutlet, hence the rapid spread. Seeds remain viable for several years so vigilance is a must. One plant is capable of producing 200-5,000 seeds in one growing season. Use caution to prevent further spread of this Idaho Noxious Weed!