War on Weeds — Weeds are Everybody’s Problem

Black Henbane

Black henbane (Hyoscyamus niger) is an annual or biennial native to the Mediterranean region. It was originally introduced for ornamental and medicinal purposes. It invades fence rows, roadsides, pastures and meadows. All parts of Black henbane are poisonous to humans and livestock. Livestock will usually avoid it but will consume it if no other feed is available.

Black henbane starts as a rosette and then bolts, growing up to 3 feet tall. It has large leaves (6 inches wide and 8 inches long) that are coarsely toothed. Leaves have a prominent cream-white colored midrib. It has funnel shaped flowers that are cream-yellow on the edges and brown to black towards the center. After flowering, 1-inch-long pineapple shaped fruits appear in rows of two. Black henbane can produce 10,000 to 500,000 seeds per plant. The plant has an unpleasant smell especially when crushed.

Integrated Pest Management (IPM) options

• Prevention — Learn to identify this plant. Never transport unknown plant material. Always plant clean seed.
• Mechanical — Hand digging or pulling can be effective on small infestations. Be sure to wear gloves, long sleeves and pants to avoid skin irritation. Pull when soil is moist to remove as much of the root as possible. Cultivation can be effective if repeated annually. Mowing prior to seed production can also be an effective form of control.
• Cultural — Establish a healthy stand of beneficial plants that will compete for essential resources. Burning mature plants that have produced seed can kill seeds and reduce seeds entering the seed bank.
• Chemical — Dicamba, Metsulfuron and Tordon are herbicide active ingredients that can effectively control this weed. Always read and follow herbicide label directions.

Idaho is a wonderful place with awesome natural resources, landscapes, agriculture and recreational opportunities. Weeds threaten all the things that we love about Idaho. To detect, contain and control weeds in Idaho we have declared “War on Weeds.” These short articles are designed to give a brief description of each species, an explanation about why it’s a problem, insights into identification and Integrated Pest Management control options. — Justin Hatch

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• Black Henbane, 7-24