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Scentless chamomile

Scentless chamomile

Scentless chamomile

(Tripleurospermum inodorum)

Priority: -  Control

Tags: Agricultural | Terrestrial | Biocontrol

Identification and Reproduction

Identification: 

  • Scentless chamomile, also known as mayweed, is an annual or short-lived perennial plant. 
  • Stems are erect, branching, green and range from 20 to 80 cm tall. 

  • Leaves are alternate, pinnately lobed, narrow and sharp-pointed. Leaves appear feathery and have branching lobes. 

  • Daisy flowers are found at the end of stems. Ray flower petals are white and 10-25 petals will attach to the yellow centre disc. Yellow button centre will become more dome like with maturity. Overtime the ray leaves will droop and then wilt away.

Reproduction:

  • This plant reproduces by seed. 
  • Dense patches of scentless chamomile can produce up to 1.8 million seeds per square meter. 
  • Seeds can remain viable in the soil for 15 years. 

Habitat & Ecology

  • Common in fallow fields, wastelands, newly sown lawns, roadsides, potato fields, vegetable patches and seldomly hay fields. 
  • Prefers sites with a high moisture level and is often near ponds, streams and other ares that are seasonally flooded. 
  • It is found throughout BC, but is a problem specifically in the Kootenay, Okanagan, Peace River and Thompson region. 

Impacts

Social:

  • Seeds contaminate hay cultivation. 
  • It is unpalatable to livestock. 
  • Its presence will reduce crop and pasture harvests. 

Ecological: 

  • Can form monocultures near waterbodies or riparian areas, altering the hydrological systems. 

Management

Mechanical/Manual Control: 

  • Mowing prior to flower formation and seedset can help reduce seed production. 
  • Continuous shallow tillage can be effective in controlling new establishing seedlings. 
  • Small infestations can easily be hand pulled before seedset. 
  • Monitor and remove any regrowth throughout the growing season. 
  • Dispose of plant material in the landfill. 

Biological Control:

  • Several biological control agents have been released in northeastern BC to manage scentless chamomile. 

Chemical Control: 

  • Herbicide should be applied early in the growing season prior to flower production. If this is not possible herbicides are still effective when plants are green and growing. 
  • Registered herbicides include picloram, aminopyralid, metsulfuron methyl, dicamba, 2,4-D and MCPP. 
  • Always read and follow the chemical product label prior to use. 

Resources

Download the Invasive Species Council of BC's factsheet on Scentless Chamomile here

Header photo (Hanna Zelenko).