Scentless Chamomile
(False chamomile, scentless mayweed)
What does it look like?
Scentless chamomile (Matricaria perforata Merat.) can be an annual, biennial or short-lived perennial that reproduces and spreads by seed. It has white, daisy like flowers 2-3 cm in diameter that are solitary on the ends of the stems. The leaves are alternate, very finely divided and fern-like. When crushed, the leaves have no scent, hence the name 'scentless'. Stems can grow from 15 cm to over 1 m tall and have numerous branches.
Its weedy nature...
Scentless chamomile is a non-native plant of European origin that came to Canada about 60 years ago. It is a very aggressive weed in hay fields, farmyards, pastures, roadsides and reduces yield in cultivated crops such as lentils and flax. It is also found in urban areas in vacant lots, in depressions and around sloughs. It does not compete well with heavy crop stands and is not usually a problem in canola and cereals. This plant is nutritionally poor and is generally not grazed by livestock.
Flowering occurs anytime between May and October, and because of this, flowers, immature seed and mature seed can all be present on the same plant. Each plant can produce up to 1 million seeds! Seeds are light and can float up to 12 hours on the surface of water. Seeds can also remain viable in the soil for up to 15 years. These features are the key to scentless chamomile's success.
Pasture, lawn or other non-crop control
Care must be taken, especially in cultivated crops to ensure that plants do not set seed. All equipment used should be thoroughly cleaned to prevent seed transfer to pristine sites. The best means to control the spread of scentless chamomile is to prevent it from being introduced into an area in the first place. Once well established, and after the plants have overwintered, eradication is difficult.
Any feed purchased should be free of weed seed. If cattle feed is contaminated with scentless chamomile, be sure to keep animals contained and treat the area each year in order that plants do not set seed.
For small infestations, hand pulling before flowering is really the most effective means of control. Plants should be burned or bagged and disposed of in a sanitary landfill. Mowing will initially prevent seeding out however plants will simply produce more flowers again below mowing height in the leaf axils. Shallow tillage before the plants flower can be used to break up the roots and seedlings. This is best done on a hot, dry day so that the roots will dry out quickly. Preventing seedlings from overwintering is very important.
Several herbicides are available for control in cereal crops and Lontrel is recommended in canola. Ally and Grazon can be used in a grass only pasture or forage situation and Lontrel can be used on non-crop farmland. Cost-effectiveness of herbicide application is maximized when treating young plants that have not yet flowered or overwintered. It is important to leave vegetation that can compete with newly emerging seedlings following herbicide treatment.
Always follow any grazing or cropping restrictions and instructions on the label.
Further Information
Transportation and Agriculture Services
780-417-7100
Photographic credits to Alberta Agriculture, Food and Rural Development, the British Columbia, Ministry of Agriculture, Food and Fisheries, Field Guide to Noxious and Other Selected Weeds of British Columbia and Strathcona County, Transportation and Agriculture Services.
Last updated: Wednesday, March 31, 2010
Page ID: 3505