The Strategy - This noxious perennial plant invades waterways. This plant is unique in that it has triangular stems and produces pink to white flowers that are shaped like an umbrella. This rhizomatous plant needs to have its bulbous roots in water or mud and can grow 3 to 5 feet above the water surface. The leaves of this plant will spiral toward the tip but are normally not noticed as the plants stems dominate the appearance. This plant is found along canals, ditches and reservoirs south of Idaho Falls.
The Attack - The plant can grow into thick vegetative pockets thus prohibiting the water from flowing as well as interfere with motor boats. In one canal it has gone from 5% invasion to over 50% invasion in three years. When it appears in marshy areas, it dominates as it is undesirable for food and the wildlife selects out the forageable plants which leaves the Rush behind. It also causes an increase in mosquitoes due the amount of undisturbed water.
The Defense - The greatest defense for this weed is to not spread it around. It has been found in some ornamental ponds, so donít plant it or move it to another site. Ensure that your watercraft and wading gear is clean of plant material when leaving the waterfowl hunting or boat launching site (throw the plants onto the ground, not into the water). Once established, digging this plant is difficult but may be your only option. Herbicides are a challenge as this plant has very little leaf surface and herbicides may not be used in many situations. Most groups use mechanical control as either chaining or possibly a specialized trackhoe. Help stop the spread of the weed by not moving the plant to new sites.
For more information, click on the link below to download the Idaho's Noxious Weeds Control Guidelines publication produced by the University of Idaho Extension.
U of I Idaho's Noxious Weeds Control Guidelines (183 KB PDF download)