Burdock, which has the botanical name "Arctium minus," is an invasive weed that has heart-shaped leaves that grow up to 14 inches wide at full maturity. This makes the plant extremely unsightly in lawns, and it quickly kills out surrounding native vegetation due to lack of sunlight. Killing burdock weeds typically takes a full season and requires chemical control to eradicate the extensive root system, and mechanical removal to prevent seeding.
Fill a large pump-powered garden sprayer with .142gr. of an herbicide that contains clopyralid. Clopyralid is a selective herbicide that is safe to use around other grasses and vegetation.
Dilute the herbicide in 1 gallon of water and close up the sprayer. Shake the sprayer for 8 to 10 seconds to mix it up.
Hold the sprayer nozzle 10 to 12 inches from the burdock leaves and saturate them with the herbicide solution. Spray as many of the leaves and the stems as you can.
Examine the area after one week to see if all of the burdock weeds are brown and dead. If any green portions remain, respray them with the herbicide mixture to finish them off.
Monitor the site through the fall months and pull up any new burdock weeds that sprout up using your hands. When you pull them out, pull straight up so you remove the long tap root from the soil instead of breaking it off.
Instead of hand weeding out the small burdock weeds that may emerge, keep the grass mowed to prevent the new weeds from dispersing seeds. If they do not disperse seeds, no more will grow once the burdock plants die in the winter. Herbicides containing the ingredient glyphosate also kill burdock, but they kill all surrounding vegetation as well.