Identification and Reproduction

Identification:

• Grows between 0.5 to 3 metres tall
• Thick, fleshy taproot
• Rosette form in first year, bolts in second year
• Stems are grooved and upright in the second year, and are red towards the base of the stem

• Flowers are purple on green burs, and are about 2.5 cm in diameter 
• Flowers are at ends of branched stems and bloom from July to September
• When mature, flowers are brown, circular burs that attach to animals, clothing and equipment

• First year leaves are in a rosette formation of large, heart-shaped leaves with hairy undersides and wavy edges
• Second year leaves are alternating, dark green and are on a bolting stems, have hairy undersides, and either toothed or wavy leaf margins

Reproduction:

• Reproduces soley by seed
• Disperses easily by burs that attach to humans, animals and equipment
• Seeds produced from July to Septmber, and are shed from September to the following spring
• Each plant produces between 6,000 and 16,000 seeds

Habitat & Ecology

• Commonly found in disturbed areas or in moist, fertile soils with high nitrogen contents
• Found along roads and in riparian areas

Impacts

Ecological:

• Outcompetes native vegetation, leading to losses in biodiversity
• Has allelopathic properties- burdock released chemicals that inhibit the growth of other plants 
• Bats and birds can become entangled in burs 

Economic/Social:

• Crowds out native forage species in pastures
• Taints dairy products- milk from cows consuming burdock has a bitter taste
• Burs become entangled in hair of livestock, reducing both quality and value

Management

Mechanical/Manual Control:

• Mechanical/manual control is the most effective method for controlling infestations of burdock
• Small infestations or plants can be hand pulled
• Can dig up burdock plants, being sure to remove the entire taproot
• Remove all plant materials from site, and ensure proper disposal

Chemical Control:

• Chemical control rarely used due to effectiveness of mechanical methods
• Foliar application can be used
• Most effective on first year rosettes

Resources

• Common burdock: Sea to Sky Invasive Species Council
• Fact Sheet for Common Burdock: Colorado Department of Agriculture
• Common burdock: Washington State University Whitman County Extension

Header photo: Ohio State Weed Lab, The Ohio State University, Bugwood.org