White cockle (Silene alba) is a biennial or short-lived perennial that spreads through seed. Like Canada thistle, plants are either male or female, so not all plants will produce seed.
It is commonly mistaken for bladder campion or night-flowering catchfly.
Stems are hairy but not sticky and grow 30-120cm tall. They have swellings at the nodes.
Leaves are hairy and soft, and borne oppositely.
Flowers and Fruit
Flowers are white or pinkish and fragrant, with five notched petals and a bulbous calyx at the base. This calyx contains the seeds, which scatter easily when the fruit matures.
White cockle prefers full sun and rich, well-drained soils. It frequently invades hay lands and is subsequently spread as the bales are moved from field to field.
White cockle seed resembles many forage seeds, such as alfalfa and clover, making it almost impossible to remove from these crops.
Due to its prolific seed production, it doesn't take long for a single plant to become an infestation. Removing and destroying new or isolated plants is extremely important.
Frequent mowing may reduce seed production but does little to eradicate infestations. Hand pulling is difficult, as white cockle has a thick taproot that breaks off at the soil surface and readily grows a new plant.
Herbicide resistance has been confirmed in several populations of white cockle. Also, its hairy leaves readily shed herbicide solution, making it difficult to apply adequate chemical concentrations.