Mayweed Chamomile, Anthemis cotula L., is native to the Mediterranean region, but has been widely introduced as a weed in the temperate zones. In 1995, it could be found in almost all of the lower 48 states.
Mayweed is an annual bushy, ill-scented herb; however, mayweed is highly attractive to ladybird beetles that feed on aphids. The plant grows from ½ to 2 feet tall. Mayweed can be found in flower from May to September but the main flowering period is June to July. The flowers are white, commonly 12, and up to ½ inch long.The flowers are pollinated by insects, mainly flies. Mayweed chamomile is potentially allelopathic to certain forage species.
Mayweed chamomile is frost-hardy at the rosette stage and may grow as a winter annual. It is moderately drought-resistant, and summer drought may restrict the size of the plant, but does not prevent seed development. Once the mayweed becomes established, eradication is impossible. Mayweed chamomile is a serious problem in cereal crops, waste areas, pastures, and along roadsides. Contact with mayweed can cause skin rashes and irritation to the mucous membranes of livestock.
Combinations of rotation grazing and herbicides treatments are the best methods of successful control of mayweed chamomile in pastures.
It is most important to prevent the production and spread of mayweed chamomile seed. Seed is dispersed by water in ditches and streams, in contaminated crop seed, and by animals or equipment. Prevent seed production whenever possible; sow clean seed, manage animal movement to avoid infested areas, and clean equipment whenever it is moved from infested to uninfested areas. Agricultural seed, hay, and livestock feeds may become contaminated with mayweed chamomile seed. Always select and use certified weed-free forage, feed, and seed to prevent reinfestation of an area. Quarantine livestock known to have been in areas infested with mayweed chamomile. It may be necessary to clean the animals’ coats before they are moved to un-infested land.
Biological Control: There are currently no biological control methods available for mayweed chamomile. Manage livestock grazing to improve the competition of desirable grasses and legumes and avoid overgrazing of plants.