Dodder (Cuscuta spp.) Biology and Management

Guide A-615
Revised by Leslie Beck
College of Agricultural, Consumer and Environmental Sciences, New Mexico State University

Author: Extension Weed Specialist, Department of Extension Plant Sciences, New Mexico State University. (Print Friendly PDF)

Introduction

There are over 150 species of dodders (Cuscuta spp.) worldwide. A member of the Convolvulaceae plant family, dodders are annual parasitic plants that reproduce by seed. They do not have any leaves or chlorophyll to live from, and must therefore obtain all of their growth requirements (water, minerals, carbohydrates) by attaching themselves to other living green plants (host plants). Host plants include those grown for agricultural purposes, ornamental plants, range plants, and weeds.

Description and Life Cycle

In the spring, dodder seeds germinate near the soil surface and send up slender, thread-like twining stems varying in color from pale green to yellow or orange and without any cotyledons (seed leaves). The slender, leafless, thread-like stem sways or rotates slowly until it touches the stem or leaf of another plant and begins to wind around it (Figures 1 and 2). On a host plant, the dodder stem will immediately form small appendages called haustoria (tiny sucker-like roots), which penetrate the stems or leaves so that dodder can extract its necessary growth requirements. Soon after attaching to a host plant, the lower end of the dodder withers and breaks its connection with the ground, while the upper part of the stem grows rapidly, often forming dense, stringy masses. However, if the dodder seedlings are unable to make physical contact with a susceptible host plant soon after germination, they will not survive.

Figure 1. Dodder parasitizing a puncturevine (Tribulus terrestris) plant.

Figure 2. Dodder stems wind around the plants they parasitize. (Photo by J.M. DiTomaso; used with permission.)

Dodder flowers are numerous, tiny, and whitish to pinkish, and form in small clusters along the stems, generally from May to October depending on the species and location. Each flower forms a small, globular seedpod with 2 to 4 seeds (Figures 3 and 4). The seeds have rough coats and vary in size depending on the species, and may be able to survive over 20 years in the soil.

Figure 3. Dodder flowers in small clusters along the stems.

Figure 4. Close-up of a dodder flower cluster. (Photo by J.M. DiTomaso; used with permission.)

Problems

Although there are several species of dodder distributed throughout North America, the most common species in the western U.S. are large seed dodder (C. indecora) and field dodder (C. campestris). These species have become a major economic concern in alfalfa, clover, tomatoes, and potatoes. Dodder infestations reduce crop yield and increase harvesting costs. The damage of dodder to the host plant varies from moderate to severe depending on the growth of the host plant and the number of haustoria attachments to the host plant.

Management

Dodder management is only achieved using combined preventive, cultural, mechanical, and chemical methods that aim to control existing populations prior to seed production and control subsequent seedlings. Fields with a history of dodder infestation need to be monitored frequently, and new dodder plants must be removed as soon as possible.

Prevention

Preventive management includes planting dodder-free crop seeds, cleaning agricultural machinery before moving from an infested area to a non-infested area, and managing existing populations prior to seed production so as to not spread dodder seeds. While small infestations can be removed by hand to prevent the production of seed, the recommendation for controlling extensive infestations is to remove the host plant and, if possible, replant with non-host crops.

Cultural Control

Planting non-host grass crops (e.g., corn, sorghum), winter crops (e.g., winter wheat, broccoli, legumes), and transplanted trees with bark (e.g., pecan) can be effective in managing dodder in an infested area. However, certain broadleaf weeds, such as pigweed, puncturevine, lambsquarter, Russian thistle, and field bindweed, serve as dodder host plants and will need to be controlled as part of a successful dodder management strategy. Furthermore, due to the longevity of dodder seed, once a host crop is planted again, fields need to be monitored regularly, and new dodder plants must be removed immediately.

Mechanical Control

Dodder infestation can be decreased by hand pulling, burning, cutting, or close mowing of the infested plants. If growers decide to use cultivation for dodder control, cultivation should be done prior to dodder’s attachment to the host plant.

Chemical Control

Several post-emergence (POST) and pre-emergence (PRE) herbicides are effective for dodder control/suppression. Common PRE herbicides (applied prior to dodder emergence) for dodder control include Kerb (pronamide), Treflan (trifluralin), and Prowl (pendimethalin). POST application (applied after dodder emergence) of Dacthal (DCPA), Scythe (pelargonic acid), Raptor (imazamox), Pursuit (imazethapyr), or Gramoxone (paraquat) has been shown to be effective in dodder control/suppression (Table 1). Broadcast or selective (spot treatment) application of Roundup (glyphosate) has also been shown to provide good control of dodder; however, spot treatments of Roundup will result in crop injury in non-Roundup Ready crops.

Acknowledgments

The critical reviews of this article by Dr. Jill Schroeder, Ms. Cheryl Fiore, and Mr. Mike Cowbrough are acknowledged.

References

Alex, J.F. 1998. Ontario weeds [Publication 505]. Guelph: Ontario Ministry of Agriculture, Food, and Rural Affairs.

Cudney, D.W., S.B. Orloff, and J.S. Reints. 1992. An integrated weed management procedure for the control of dodder (Cuscuta indecora) in alfalfa (Medicago sativa). Weed Technology, 6, 603–606.

Dawson, J.H., and A.R. Saghir. 1983. Herbicides applied to dodder (Cuscuta spp.) after attachment to alfalfa (Medicago sativa). Weed Science, 31, 465–471.

DiTomaso, J.M., and E.A. Healey. 2007. Weeds of California and other western states [Publication 3488]. Davis: University of California Agriculture and Natural Resources.

Lanini, W.T., D.W. Cudney, G. Miyao, and K.J. Hembree. 2002. Dodder. Davis: University of California Agriculture and Natural Resources. Retrieved April 2, 2009, from https://www.ipm.ucdavis.edu/PDF/PESTNOTES/pndodder.pdf

Whitson, T.D., L.C. Burrill, S.A. Dewey, D.W. Cudney, B.E. Nelson, R.D. Lee, and R. Parker. 2006. Weeds of the west, 9th ed. The Western Society of Weed Science in cooperation with the Western United States Land Grant Universities Cooperative Extension Services.

For further reading

A-325: Managing Weeds in Alfalfa
https://pubs.nmsu.edu/_a/A325/

A-340: Integrated Weed Management in Irrigated Permanent Grass Pastures and Hayfields in New Mexico
https://pubs.nmsu.edu/_a/A340/

H-158: How to Collect and Send Specimens for Disease Diagnosis
http://aces.nmsu.edu/pubs/_h/H158/

Original authors: Jamshid Ashigh, Extension Weed Specialist; and Esther E. Marquez, Research Assistant.

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Leslie Beck is the Extension Weed Specialist at New Mexico State University. Her research program focuses on integrated weed management systems in landscape, horticultural, and agronomic crops. Her Extension work provides the citizens of New Mexico with accurate, applicable, and effective weed identification and management strategies in multiple cropping systems.

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Revised April 2018 Las Cruces, NM