Prickly Lettuce

Invasive:

 

Annual Sow Thistle (Sonchus oleraceus) is also invasive; it has larger flowers than Prickly Lettuce.

 

 

 

 

 

 

 

Perennial Sow Thistle (Sonchus arvensis) is another invasive plant that has larger flowers than Prickly Lettuce; it is also distinguishable by its rhizomes.

Prickly Lettuce was introduced from Europe. Its presence dates back to the late 19th century; it is speculated that it was introduced as a contaminant in seed.

Prickly Lettuce tends to prefer dry conditions. It occurs along dry roadsides, thicket clearings, agricultural areas, abandoned fields and other disturbed areas. It is also commonly found at waste disposal sites.

Prickly Lettuce is a biennial weed; in its first year, it forms a rosette, which will bolt and go to seed the following year.

Prickly Lettuce is propagated by seed, and is predominantly self-pollinated. Its seeds germinate with the onset of winter rains.

The tall stalks, lightweight seeds, and parachute-like pappus (cluster of hairs) help spread the seeds in the wind. Seeds can also spread through water or attach to fur or feathers.

Prickly Lettuce is currently found throughout the Sea to Sky Corridor, so the best approach to controlling its spread is by PREVENTION.

 

Learn to identify Prickly Lettuce: use the images presented in this profile page to learn how to identify Prickly Lettuce.

What to do if you spot it: You can report any Prickly Lettuce sighting by clicking here.

 

DO:

• Regularly monitor properties for weed infestations.
• Ensure soil and gravel are uncontaminated before transport.
• Check wildflower mixes to ensure that they do not contain Prickly Lettuce.
• Ensure that plants are disposed of in a garbage bag if found in floral arrangements to prevent seeds from spreading.

 

DO NOT:

• Do not unload, park or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
• Do not plant Prickly Lettuce in a garden, no matter how well-contained its enclosure may seem.
• Move soil that has been contaminated with Prickly Lettuce.
• Do not compost!

 

Control

Mechanical

• Prickly Lettuce is easily controlled by cultivation or pulling.
• Mowing is not effective because the plants will readily produce new stems or flowering branches.
• It is recommended that you wear gloves and long sleeves to remove Prickly Lettuce, as the leaves are spiked.

Chemical

• Rosettes can be killed with non-selective herbicides containing glyphosate, with larger rosettes requiring higher concentrations.
• Other effective herbicides include 2,4-D, MCPA, dicamba and clopyralid.
• Plants are difficult to control with herbicides once the flowering stems have begun to elongate.
• We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.

Biological

There is no biocontrol available for this plant.