Q: What is this vine growing around my shrub?
A: Thank you for bringing it in, it made the identification much easier. You have dodder plant, which belongs to the genus Cuscuta. There are more than 150 species of dodder plants worldwide. They are unusual plants because they do not possess leaves or roots and do not contain chlorophyll. This means dodder must obtain its nutrients from other plants therefore it is a parasite.
It reproduces by seed only but it produces prolific amounts of seed. If left unchecked, it will totally take over large sections of plant material. The long, thread, vine-like structures are actually stems which wrap around the stems and trunks of other plants. The seeds have been known to survive in the ground as long as twenty years. Once they do germinate, if they do not attach quickly to other plant material they will wither and die. Mechanical removal works best when the plant population is small. Often the host plant must also be removed in order to obtain complete control. Regular monitoring of the area should be done for the first few years to ensure the pest does not return.
Pre-emergent chemical control works best using products containing the active ingredients: pronamide, trifluralin, or pendimethalin. Post-emergent products such as imazamox or paraquat will suppress the vine but not necessarily control it. The non-selective glyphosate will control dodder but will also kill the host plant. It is commonly known by other names such as vampire vine, love vine, Witches shoelaces or Devilguts, none of these names are very attractive which is appropriate for this plant.