PARASITIC DODDER (CUSCUTA SPP.)
A parasitic, annual forb with thread-like yellow to orange stems and no true leaves. The stems adhere to a host plant and coil around the foliage, sometimes forming dense mats. Suckers produced from the stems penetrate the host and extract food from it. Clusters of tiny white or cream flowers produce rounded seed pods, each containing 1-4 tiny, rough seeds.
Habitat and ecology
Dodder prefers mid-elevation habitats in the dry interior of BC, and low-elevation coastal areas. It proliferates in cultivated crops.
Vegetable and forage crops are often attacked by dodder, reducing vigor and quality. Dodder is an alternate host to viral diseases that affect vegetables. Dodder stems can become entangled in equipment. Native species are also affected by dodder, particularly the sunflower and goosefoot families.
It is essential to treat new infestations before they become established. Plants can be hand pulled and burned before seeds ripen. Burning infested patches of fields can also be effective. Tillage will not make a significant difference. Equipment, footwear, and tools should be cleaned before leaving an infested site. Infested hay should not be bought or sold, and if livestock have eaten infested hay, they should be kept in an infested area until the seeds have passed through their system. Herbicides are effective; chlorpropham can be used in alfalfa fields, and non-selective herbicides are recommended for roadside and non-crop situations. Be sure to check with the BC Ministry of Agriculture, Food and Fisheries Crop Production Guides for herbicide recommendations.
Province of British Columbia. 2002. Guide to Weeds in British Columbia.
Photo reference: Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org