THE ISSUE:  Policeman’s Helmet

 Policeman’s Helmet (Impatiens glandulifera) is herbaceous annual native to Asia that was introduced into the U.S. as an ornamental. It invades areas with high soil moisture including riparian areas, ditch banks, swamps, roadsides, and other moist areas. 

 Policeman’s Helmet can grow up to 8 feet tall, with hollow stems that can be up to 2 inches in diameter. Leaves can grow up to 9 inches long has serrated edges and are arranged opposite from each other (sometimes whorls of 3). It was given its name because the flowers resemble a helmet worn by British police. Flowers are formed in clusters of 2-14 and can be purple, white, or pink. When seed pods are mature, they explode, launching seeds up to 15 feet. Seeds can remain viable for 2 years or more.

Integrated Pest Management (IPM) Options: 

• Prevention— Learn to identify this plant. Never transport unknown plant material. Always plant clean seed! Unfortunately, Policeman’s helmet seed can still be purchased, and it goes by several other names. Know what you are planting!

• Mechanical— Hand pulling can be an effective control method for small infestations. Pull this weed before seed pods mature. Handling this plant after seed pods are mature will allow this plant to spread. Mowing or tillage can also be effective, if done before seed is mature.

• Cultural— Establish a healthy stand of beneficial plants that will compete for essential resources.

• Chemical—Apply herbicides before flowering occurs. Glyphosate, Triclopyr, 2,4-D, and Metsulfuron are herbicide active ingredients that can be effective. Care should be taken when using herbicides near water, as water can transport herbicides to non-target species. Always read and follow herbicide label directions!

Justin Hatch, University of Idaho Extension Agriculture Educator in Caribou and Bear Lake Counties. 208-547-3205
[email protected]