Because dodder is an annual, it must reproduce from seed. Plants present now will be killed by the first frost this fall. Seed may sprout in the spring or lie dormant for a number of years. Germination takes place in the soil, but roots die as soon as the plant finds an acceptable host. After attachment, dodder lives completely off the host plant. A single dodder plant can spread by branching and attacking additional host plants.
Destroying the host plants can control dodder, but this may not be an acceptable solution for many people. Dodder cannot be destroyed by pulling it off the host plants because remaining stem pieces will continue to grow. Trifluralin (Preen, Miracle-Gro Garden Weed Preventer, Treflan, Hi-Yield Herbicide Granules Weed and Grass Stopper) is a preemergence herbicide that can be used for control if applied before the dodder seed germinates. Also, glyphosate (Round-up, Kleen-up, Killzall, etc.) is effective on dodder. However, glyphosate is nonselective and will kill whatever it hits, including the host plants. (Ward Upham)