Fred from Boardman submitted this photo to the OSU Extension Plant and Pest Clinic of a vine growing around his petunias. Master Gardeners identified it as a dodder vine, a parasitic plant also known as a strangler weed. (Submitted photo)

Q: There is something growing around my petunias. Can you tell me what it is and how to get rid of it?

— Fred from Boardman

A: Thanks, Fred, for bringing in photos of the problem weed. What’s growing around your petunias is a parasitic plant called a dodder vine.

While it is uncommon, the dodder vine is hard to control and can damage or kill a host plant. And while it is a pest, dodder has an extraordinary life cycle, different from most other plants.

Dodder vine (also known as strangler weed, hairweed or angel’s hair) is a member of the Cuscuta plant genus and a part of the morning glory family. The University of Florida says there are 150 species found worldwide.

In the tropics it grows as a perennial, but in our area it’s an annual.

Dodder relies on its host plant for its survival. The vine has thin, string-like stems with very small leaves it.

The dodder vine has little to no chlorophyll, so it is not green in color. Chlorophyll is a green pigment that gives plants their green color and conducts photosynthesis. Lacking its own chlorophyll means dodder can’t produce its own food and must hijack its nutrition from other plants.

The dodder vine isn’t picky about what plants it attacks. Hosts range from woody shrubs to agricultural crops to petunias and other ornamentals.

When a dodder seed sprouts, it starts a small root system while the top part of the plant begins seeking a host. If a host isn’t found in about a week, the dodder vine dies. If a host is found, the seedling wraps itself around the host and produces a special type of adventitious root called haustoria. These haustoria penetrate the host plant and begin extracting nutrients and water from it.

When the dodder attaches to a host its original root systems dies, and the vine then lives completely off its host.

The dodder vine continues to grow and entangle itself around its host eventually smothering it and maybe killing it. During this time, the dodder flowers and makes seeds for the next generation. The seeds of the dodder vine can wait in the soil up to 10 years for the right conditions before germinating.

What can you do about the dodder vine? If dodder vine is already entangled with a host plant, it is too late to stop it. Pulling the vine off won’t work because new vine will grow back from the haustoria. Pruning and chemicals are not effective.

The only option is to remove the host plant and vine before the dodder vine goes to seed. Dodder can be stopped if you get to it before it attaches to a host. This makes identifying any strange weeds you see important.

If you need help identifying a weed, bring a sample to us.

For more on dodder vine, including photos, go to http://go.osu.edu/dodder.

Sprague is an Ohio State University Mahoning County Extension Master Gardener Volunteer. The Extension Office’s Plant and Pest Clinic is open 9 a.m. to noon Mondays and Thursdays for help with plant issues, soil testing and insect identification. Find details at go.osu.edu/mahoningclinic.