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 A Guide to Weeds in British Columbia for Scentless Chamomile here.

Header photo (Hanna Zelenko).