Larimer County Weed District Identification and Management of Common mullein (Verbascum thapsus)

Common mullein, also referred to as woolly mullein, velvet dock, flannel leaf, Aaron's rod, torch plant, miner's candle, is a biennial in the Figwort family (Scrophulariaceae) that is native to Asia. A biennial is a plant that completes its life cycle in two seasons or 2 years. The first year is spent as a rosette (see picture). The rosette does not produce seeds this first year because a flower is not formed. The second year, common mullein produces a single, thick stem from the center of the rosette. Yellow flowers are formed from this stalk. In Larimer County, common mullein tends to be most invasive in drainages of gravelly soils, particularly Estes Park. This plant is a prolific seed producer and thus control requires prevention of seed production. One of the best ways to prevent seed production is to spray with a herbicide during the rosette stage. Herbicide uptake by this plant is difficult due to the woolly nature of the leaves. Selective chemical control (only broadleaf plants are affected) of this plant can be achieved with Telar (1-3 oz/A), Escort (1-2 ounces/A), and Ally 1/10 to 2/10 oz/A. Non-selective control (all contacted vegetation is affected) can be achieved with glyphosate products such as Rattler, Razor, Roundup, Credit, and Rodeo for aquatic sites. See label for specific rates and timing of application. However, these herbicides, in general, are applied when the plant is actively growing; preferably when the plants are in the early bud stage. It is also recommended to use a surfactant and penetrator when applying these herbicides.

The above picture shows common mullein in the second season's growth stage. Seeds are produced from the yellow flower. Below is common mullein in the first year of growth, the rosette stage. Leaves are thick and woolly and therefore unplalatable to livestock. The texture of the leaves also makes herbicide penetration difficult.

	Mullein Control
		Mechanical control such as mowing or handpulling can be effective is completed before seed production. The early bud stage, which would be before yellow flowers appear, is recommended. When flowers have turned brown is when the plant has gone to seed (see picture). Common mullein does not produce seeds simultaneously, therefore you will see stalks that have seeds, flowers, and buds. The relevance of this is to mow, pull, or cut the stalk earlier in the summer because some flowers will produce seeds early in the season. There is a mullein seed head weevil (Gymnetron tetrum) that reduces seed production. Insects can be purchased for approximately $80 per release from Integrated Weed Management, 1-888-319-1632. Another alternative to chemicals is altering the soil fertility. According to Weeds: Control Without Poisons (Walters 1999), the best way to control mullein is to cancel out seeds in the soil with humic acid, fertilization and engineering a crop jump on weeds. Calcium, soft rock phosphate, sulfates, humates and potassium will help reduce or eliminate this weed. In his opinion, the use of potassium chloride and the resultant reduction in microbial activity are often factors that give farmers this weed. If you have any further questions regarding this weed, please contact our office, 970-498-5768.
					The above picture depicts common mullein in the flower and seed phase. When a stalk begins to brown, then seeds have been produced. Mowing should occur before yellow flowers appear.
				The picture above depicts mullein in the flowering stage. Flowering occurs from June to August.

Top of Page

Back

Back to Weed District Home

Back to Parks & Open Lands Home