Working together to strengthen and support noxious weed management efforts in Montana.

Weed of the Week – Blueweed

Thursday, August 12th, 2010

Blueweed - photo by Kellieanne Morris, Ravalli County MT Weed District

Blueweed - photo by Kellieanne Morris, Ravalli County MT Weed District

Introduction

Blueweed or viper’s bugloss is native to Europe and has invaded much of the eastern U.S. and parts of the western U.S.  The first record of this plant in Montana was in 1916.  It was listed as a category 2 noxious weed on our state list in March of 2008.  Blueweed thrives in gravel bars along rivers and also does well in irrigated pastures.

Concerns
Blueweed can be toxic to horses, sheep, and cattle.  The hairs that cover the plant may also act as a skin irritant for humans.  This plant can become quite large greatly reducing the productivity of grazable lands due to it being unpalatable.  It has the potential to ruin hay due to its high moisture content.  It also has the ability to destroy wildlife habitat and native plant biodiversity.  It reproduces by seeds that stick to clothing, animal fur, and feathers and may also be disperse by flowing water.  Each plant produces between 500 and 2000 seeds.

Identification
Blueweed is most easily identified by its bell shaped flowers that come in shades of blue, pink, and purple.  The flowers bloom a few at a time in a scorpoid raceme (resembles a scorpion’s tail).  Four or five, usually pink stamen stick out from the center of the bell shaped flowers.  Blueweed is a biennial, meaning that it lives for two years.  The first year that this plant emerges it is in the form of a rosette.  Second year plants typically bolt and produce flowers.  The stems are a grayish-green color and are covered with hairs and black dots.  The leaves are lance shaped and are also covered with hairs.  The plant can be anywhere from 5 inches to 3 feet in height.  From a distance it may resemble lupine.

What can you do?

This tap rooted plant can be hand pulled (with gloves and long sleeved shirts) or dug up with good results in small infestations.  Mowing can help to reduce the seed production if repeated throughout the growing season but is not a long term solution.  Herbicide is an effective control method when applied correctly.  Call your local weed district for recommendations on herbicides.  As always an integrated weed management plan utilizing all effective means of control and revegetation is the best option for reducing and eradicating blueweed.  If you have any questions about blueweed or any other noxious weeds call your local weed district.

Visit the MWCA Weed ID pages for additional information and pictures of blueweed.

This series of articles was developed by Ravalli County.  If you would like to use these articles please contact Ravalli County Weed District Weed Coordinator at (406) 777-5842.

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