Weed Control
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Purple Loosestrife
Information | Images
Lythrum salicaria
Perennial
Identification and management tips
- Purple loosestrife flowers are magenta-colored and bloom from June to September.
- The root system consists rhizomes that spread rapidly to form dense mats.
- Small infestations of young purple loosestrife plants may be pulled by hand, preferably before seed set. Older plants can be removed with a shovel.
- Large infestations can be effectively controlled using either a glyphosate or triclopyr based herbicides approved for use in or near water.
- Chemical applications are most effective when applied late in the season when plants are preparing for dormancy. However, it may be best to do a mid-summer and a late season treatment, to reduce the amount of seed produced.
- For long term control of large infestations biological control is recommended.
Most effective control methods and timing
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Prevention (Prev)
Monitor and destroy new plants before seed production.
Mechanical (Mech)
Hand pulling, digging, cutting, mowing and tilling.
Cultural (Cult)
Biological control agents, livestock grazing, and revegetation practices.
Chemical (Chem)
Selective herbicides based on the plant and the specific location. Check our weed fact sheets for specific control information.
Links
- Weber County Weed Abatement: Purple Loosestrife
- USDA Forest Service: Invasive Plants Website; Weed of the Week
Photo credits
Left to right:
- Steve Dewey, USU; King County Weed Program