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Purple
Loosestrife
(Lythrum salicaria)
County Management Strategy: This species must be eradicated statewide.
Identification: A perennial with creeping, rhizomatous roots that grows up to 10 or more feet tall. A wetland invader, it thrives in moist conditions. Leaves are lance shaped with veins that do not reach the edge of the leaf but parallel the edge. The very showy purple to magenta flowers grow on long stalks and have 5-7 petals each. The ribbed stems are square or 6-sided. Also called purple lythrum.
Other names: purple lythrum, rainbow weed, spiked loosestrife, salicaire
Similar Species: An uncommon native loosestrife is shorter and more delicate, with fewer flowers. Gayfeather or blazing star, a native plant, has coarse, more linear leaves that are much narrower than loosestrife. Fireweed, a common native plant, has only 4 petals per flower, a round stem and the flower heads form an elongated triangle.
Control Timing: Before or during early flowering in the spring, and in the fall. Mature
flowerheads must be removed before the first frost.
Control target: Prevent seed production and stress root system.
Control Methods: Mechanical control can be effective for small infestations but must be
repeated, often for five years or more. Timing of herbicide applications is important. Early
summer applications should be done just before flowering to prevent flowering and seed set.
Fall applications can be done from late August through September, but before a hard freeze.
Flowerheads must be removed to prevent spread of seeds. Several biocontrol agents are
available, but establishment is dependent on proper regulation of water levels and may work
better in drier habitats. Biological control agents are available, however, it is not recommended
in Mesa County because eradication is the management goal for this species.
Status in Mesa County: Large infestations occur along Tiara Creek on the Redlands. Smaller infestations occur along Goat Draw on Redlands Parkway, on several private properties on the Redlands, in Walter Walker Wildlife Area and on several private properties near Fruita.
Scattered plants are found along the Colorado River from Grand Junction to Moab, Utah. The
spread of the weed to riparian areas along the River are of extreme concern to public lands
managers. Mesa County cooperates with landowners and state and federal agencies to eradicate
this weed. REPORT INFESTATIONS TO THE DIVISION OF PEST MANAGEMENT!
Additional Information (External
Links)
Photos:
http://plants.usda.gov/cgi_bin/topics.cgi?earl=plant_profile.cgi&symbol=LEVU
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