White Cockle (Silene latifolia ssp. alba (P. Mill.) Greuter & Burdet) )FamilyFamily: CaryophyllaceaeFamily: Caryophyllaceae Description and VariationDescription and Variation: White cockle is a 1.5 to 3.5 foot tall perennial (or sometimes biennial) plant. White cockle has hairy, jointed stems that can be spreading or nearly erect. The plant is hairy below and glandular toward the top. Its hairy leaves are opposite and simple, ovate to lanceolate. The plant is dioecious, with male and female flowers borne on different plants. The fragrant flowers, which are solitary on long peduncles or in cymose clusters, have five white or pink petals that greatly exceed the calyx. The petals are deeply notched with tiny ears on the sides. The flowers open in the evening and close by noon. The small, rounded, rough seeds are produced in a bulb-like capsule. Economic Importance: White cockle can be a serious problem in small grains, alfalfa, clover, and grass seed fields. Its seeds are difficult to separate from commercially produced clover or alfalfa seed. In Minnesota, approximately seven percent of the timothy seed intended for certification is rejected due to white cockle seed contamination (Strand and Wyse 1982). White cockle is also problematic for Washington’s timothy growers.: White cockle can be a serious problem in small grains, alfalfa, clover, and grass seed fields. Its seeds are difficult to separate from commercially produced clover or alfalfa seed. In Minnesota, approximately seven percent of the timothy seed intended for certification is rejected due to white cockle seed contamination (Strand and Wyse 1982). White cockle is also problematic for Washington’s timothy growers. Geographic DistributionGeographic Distribution: A native of Europe, white cockle has become widespread and locally common in North America, especially on rich well-drained soils. The plant is found in the eastern and north central United States and southern Canada, as well as the Pacific Northwest (Muenscher 1955). In Washington, it is a particular problem in timothy growing regions. HabitatHabitat: White cockle is found in grasslands and in new clover and alfalfa seedings, especially on well-drained soils (Muenscher 1955). While fields, roadsides, pastures, grass embankments, and waste places are characteristic white cockle habitats, the species is also found in many undisturbed areas, where it can be mistaken for a native (Hitchcock and Cronquist 1964). HistoryHistory: Brought in from Europe, white cockle was first noted in eastern Washington in 1923 (Gaines and Swan 1972). Growth and DevelopmentGrowth and Development: White cockle is a biennial or perennial (Muenscher 1955) that begins growth early in the spring. Second-year plants flower from June through September or October, shedding seed four to six weeks later. Mature seeds can germinate immediately, but many overwinter and germinate the following spring (Strand and Wyse 1982). ReproductionReproduction: White cockle reproduces by seeds and short rootstocks (Muenscher 1955). Since this species is dioecious, not all plants produce seed. However, female plants are capable of producing 1,600 to 24,000 seeds per plant (Strand and Wyse 1982). Response to HerbicidesResponse to Herbicides: Read and follow current herbicide labels and recommendations for control. Based on information from Minnesota, white cockle can be controlled most easily in field crops when it is in the seedling stage or during seed germination. In grass seed fields, Dicamba (Banvel) at one half to one 1 pint per acre works best. With small seeded legumes, Benefin (Balan), applied at 1 1/8 to 1.5 pounds per acre (depending on soil type) is the most effective herbicide for new seedings. Metribuzin, simazine, and terbacil have been used effectively on older stands in Minnesota. See Strand and Wyse (1982) for more details. Response to Mechanical MethodsResponse to Mechanical Methods: Cultivation or tillage for regular seedbed preparation will kill many white cockle plants. However, well-established plants are usually not killed, and tillage will promote seed germination. Tillage can be a suitable control in row crops or prior to seeding small-seeded grasses or legumes (Strand and Wyse 1982). Biocontrol PotentialsBiocontrol Potentials: No information available. ReferencesReferences: Anonymous. 1981. Weeds of the North Central States. North Central Regional Research Publication No. 281. University of Illinois Urbana-Champaign, Urbana, IL. Gaines, X.M. and D.G. Swan. 1972. Weeds of Eastern Washington and Adjacent Areas. Camp Na-Bor-Lee Association, Davenport, WA. Hastings, R.E. and C.A. Kust. 1970. Control of yellow rocket and white cockle in established alfalfa. Weed Science 18: 329-333. Hitchcock, C.L. and A. Cronquist. 1964. Vascular Plants of the Pacific Northwest. Part 2: Salicaceae to Saxifragaceae. University of Washington Press, Seattle. Lincoln, W.C., Jr. and M.L. McGuigan. 1976. Germination studies of two Lychnis species: Lychnis alba (evening lychnis) and Lychnis flos-cuculi (ragged robin). Newsletter of the Association of Official Seed Analysts 50: 48-50. Muenscher, W.C. 1955. Weeds, 2nd ed. Cornell University Press, Ithaca. Strand, O.E. and D.S. Wyse. 1982. Identification and control of white cockle and nightflowering catchfly. Agricultural Chemicals Fact Sheet No. 18. University of Minnesota Agricultural Extension Service, St. Paul.
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