War on Weeds—weeds are everybody’s problem

  THE ISSUE: Common teasel 

 Common teasel (Dipsacus fullonum) is a biennial weed native to Europe and Northern Africa.  It was originally introduced into the U.S. in the 1700’s. It invades rights-of-way, pastures, riparian areas, and Ag. lands. It is capable of forming dense stands that reduce forage quality for livestock. It has iconic seed heads that are commonly used in floral arrangements.

 After germinating common teasel spends its first year in the rosette stage. During the second year it bolts, sending up flowering stalks. Rosette leaves are crinkled with scalloped edges and a pale mid-rib. Stem leaves are smaller and have short spines on the mid-rib on the underside of the leaves. Lower stem leaves will fuse together, forming a bowl to catch rainwater. Stems can grow 1.5 to 6.5 ft tall. Light purple to white flowers are formed on spiny egg-shaped heads. As seed is set plants die, but they often stay standing into the following year. Each seed head contains 250 to 1,500 seeds. A single plant can produce up to 34,000 seeds per year. 

Integrated Pest Management (IPM) Options: 

• Prevention— Learn to identify this plant. Clean equipment after leaving infested areas. Plant clean seed.  
• Mechanical— Hand digging can be effective on small infestations. Mowing can be effective when done before flowering occurs.  
• Cultural— Establish healthy stands of beneficial plants that can compete for essential resources. 
• Chemical—Common teasel is best controlled at the rosette stage when actively growing. There are a number of herbicide active ingredients that can help to control common teasel, including: 2,4-D amine, 2,4-D amine + Dicamba (Rifle-D and others), Aminocyclopyrachlor +Chlorsulfuron (Perspective), Chlorsulfuron (Telar), Diflufenzopyr + Dicamba (Overdrive),Imazapic (Plateau), Metsulfuron (Escort and others), and Triclopyr + Clopyralid (Redeem R&P). Always read and follow herbicide label directions!

Justin Hatch, University of Idaho Extension Agriculture Educator in Caribou County. 

208-547-3205 [email protected]