How to deal with dodder

After twining onto the host, the dodder’s original roots in the soil die away, leaving the plant to become wholly parasitic. It most often occurs around agricultural plantings such as flax and alfalfa where it seldom poses a problem or requires treatment. 

One way to control dodder in an ornamental setting is to keep it from going to seed. Seeds are set after its small, white flowers bloom during the summer and fall. Although it is virtually impossible to pick off all the dodder from the host plant without destroying it, it is possible to cut off all the parasitized parts from the host plant as soon as the dodder appears and burn them. Another strategy is to totally remove all ornamental plantings from the beds, keeping them empty for a season. If there is nothing to attach itself to, the dodder will die. Pull out and burn any dodder seedlings when they do appear. Also, certain preemergent herbicides can be used in the spring to keep dodder seeds from germinating, but I would hesitate to use such chemicals in a home garden around children or animals. Consult your local extension agent for recommended preemergents.