University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources

May 19, 2006

Controlling common mullein in pastures

Common mullein (Verbascim thapsus) in a Nebraska pasture.
Common mullein (Verbascim thapsus) is a weed species on the increase in northeastern Nebraska’s rangeland, woodland and pastures. It is a biennial plant that reproduces only by seeds, but it is a prolific seed producer. The taproot of this species can access soil moisture from a deeper profile and at a much faster rate than fibrous roots of pasture grasses, giving common mullein the competitive advantage over grass, especially during dry years.

Common mullein usually starts growing sparsely as individual plants and then spreads. A cluster of leaves, commonly known as a rosette, with a thick hair cover is a distinct identifying feature of this species. The stem is woolly, erect and 2-6 feet tall, with no branches. Leaves are opposite, elliptic to ovate. Like many other plant species, the overall growth and development depends on the amount and timing of rainfall. In Nebraska common mullein produces yellowish flowers in June and July. It has no value to livestock because of its low palatability.

Control trial results

See the September 30, 2005 CropWatch for information on UNL field trials on controlling common mullein
Control recommendations

Ranchers need to control common mullein because heavy stands can reduce grass production as much as 50%, especially in dry years, and common mullein plants have no value for livestock forage.

Various means can be used to control common mullein. The best strategy is to control it when the species density is low. Density can easily expand from a few plants to hundreds of plants per acre over just a couple years due to prolific seed production.

Mechanical. Sparse populations can be controlled by mechanical removal using a spade or shovel in late April and early May. Individual plants can be dug out or cut at the soil surface as long as the whole rosette is removed. Single mowing of new 1-2 foot tall plants can reduce population and seed production for the season, especially in dry years.

Chemical. Herbicides also can be effective tools in providing season-long control; however, the thick wooly coat of hairs on the leaves can reduce herbicide uptake and level of control. A herbicide should be applied when the rosette has 6-12 leaves, before the stem starts to grow. This usually occurs in May in Nebraska. Effective herbicides and their rates per acre are: Grazon P+D (3-4 pts/ac), Cimarron (0.75-1.0 oz/ac), and a three-way-mix of Cimarron (0.5 oz ), Glean (0.5 oz) and RangeStar (32 oz). Make sure to use enough additives such are Crop Oil at 1-2 qts/ac to help herbicide penetrate the thick wooly coat.

Stevan Knezevic
Extension Integrated Weed Management Specialist
Haskell Ag Lab, Northeast REC

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Copyright 2006 by the University of Nebraska Board of Regents. All rights reserved.
Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture.
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