Common Teasel is the Weed for This Week
Posted: July 12, 2012
Common teasel is very apparent right now, particularly along roadsides, but it can also be found occasionally in pastures and along field edges. Common teasel (Dipsacus fullonum) is a biennial that exists as a somewhat obscure basal rosette the first year until it flowers in the second. Much of it is now blooming in the Southeast and it will soon be blooming in the northern regions of the state. The flower heads are cylindrical to egg-shaped with large spine-like bristly bracts curving up around the head, so it is very noticeable at this time (see accompanying image). The dried flower heads are often used in plant arrangements, probably helping to spread this invasive species. Common teasel is native to Europe and was introduced to North America as early as the 1700’s. It grows in open sunny habitats and seems to do well in both wet and dry areas. Teasel populations have rapidly expanded in the last 30 years and it is quite common throughout much of Pennsylvania, particularly along roadsides. Since teasel is a biennial, it reproduces from seed and the seeds are often dispersed by mechanical means including mowing equipment. A single teasel plant can produce over 2,000 seeds.
Control of teasel is similar to other biennials. Repeated mowing can effectively kill established plants or cutting or digging individual plants can be used for small infestations. The stalks of flowering plants can be cut at the base and this generally provides effective control. Cutting the stalks before buds are present may allow it to re-grow and flowering stalks should be removed and burned since mature seed may still develop. Herbicides can also be used for control, but application during the rosette stage is most effective. Triclopyr (Garlon and a component of Crossbow) and glyphosate are often mentioned as effective herbicides.