Q: I maintain a large flower bed . Several week ago, I noticed a bright yellow vine growing over one of the plants. After just a couple of weeks, it had spread over the whole bed and covered many of the plants. What is this and how can I control it?
A: You are looking at a parasitic vine called dodder, also known as Devil’s Hair. The seeds of dodder germinate in the spring and send up a short sprout which attaches to any nearby plant. The vine tendrils wrap around the plant stem and invade it with parasitic roots. The dodder extracts water and nutrients from the host plant and can severely weaken it or kill it outright.
Since you have a large flower bed, your control choices now are limited. There is no chemical that will kill the dodder and not harm your flowers. In fact, you need to pull and destroy any plants the dodder has touched, since the parasite can still grow from infected plants.
Next year you could choose to use Preen, a pre-emergent herbicide in the spring to prevent the dodder seed from germinating. However, the pre-emergent is not 100 percent effective so you will still have to perform regular search-and-destroy missions in the bed.
Dr. Tim Murphy, Extension weed specialist, says that sometimes the best option is to remove the top three inches of soil from the bed and replace it with new topsoil. In this way the dodder seeds will be eliminated and you can plant in the bed without worry.
Dodder on trees in Florida Keys