Mayweed chamomile (Anthemis cotula L.) biology and management—A review of an emerging global invader

Abstract

The globally invasive weed, mayweed chamomile (Anthemis cotula L.) is an annual, bushy, ill‐scented herb, originating in Eurasia. It is aggressively weedy in croplands, field‐side ditches, wet areas and along roadsides, especially in slightly acidic, nitrogen‐rich, clay‐loam soils. In addition to interfering with crop growth, the weed causes dermatitis and eye irritation in humans, skin rashes and sour mouth in domesticated mammals, and off‐flavours in cow's milk through forage contamination. Although A. cotula may be managed effectively with some broadleaf herbicides in cereal crops, it is much more difficult to manage in broadleaved crops and cover crops. In some regions, aggressive use of relatively few herbicides has selected for acetolactate synthase herbicide resistance in A. cotula. Therefore, A. cotula poses serious ecological and economic challenges in many regions. Despite this threat, the details of A. cotula biology and ecology in the context of environmental change remain relatively unknown. For example, the reason for the invasiveness of A. cotula remains uncertain, but is presumed to be due to abundant seed production, allelochemicals, mycorrhizal associations, minimal herbivory in invaded ranges, ability to attract generalist pollinators through an extended flowering period and adaptive capacity in a wide range of soil types and conditions. In this paper, we comprehensively review the literature and ongoing work on A. cotula and provide a research agenda to improve understanding and management of this species.

Phenotypic Trait Variation in Populations of a Global Invader Mayweed Chamomile (Anthemis cotula): Implications for Weed Management

“…Mayweed chamomile (Anthemis cotula L.) is an annual, bushy, ill-scented globally invasive weed (Kay, 1971;Adhikari et al, 2020a) that is especially problematic under the Mediterranean and Mediterranean-like climates such as in the Pacific Northwest (PNW), USA (Lyon et al, 2017) and the Kashmir valley, India (Shah et al, 2008(Shah et al, , 2009. It prefers moist soils and commonly found in poorly drained areas, disturbed lands, field edges, roadsides, and in crop fields (Kay, 1971).…”

“…In the modern era, it has been introduced, presumably as a contaminant of crop seed and other plant materials, and distributed globally (Kay, 1971;Mack and Erneberg, 2002;CABI, 2018). In Europe, it is considered as archaeophyte (anciently introduced plant species) in some countries, whereas outside this continent the species was first reported in South America (1816), followed by Africa (1838), North America (1841), Australia (1873), Antarctica (1903), andAsia (1933) (Global Biodiversity Information Facility, 2018) [details of global distribution are reviewed and reported in Adhikari et al (2020a)].…”

“…Globally, there has been limited study (if any) of the ecological and economic threats of A. cotula to the local ecosystems. It is aggressively weedy in many croplands and pastures, reducing crop yields and forage quality (Adhikari et al, 2020a). In cerealbased cropping systems worldwide, climate change is motivating producers to diversify their operations by incorporating fall-and spring-sown pulses, canola, and cover crops (Eigenbrode et al, 2013;O'Leary et al, 2018).…”

“…In cerealbased cropping systems worldwide, climate change is motivating producers to diversify their operations by incorporating fall-and spring-sown pulses, canola, and cover crops (Eigenbrode et al, 2013;O'Leary et al, 2018). In the Pacific Northwest (PNW), USA, A. cotula was first reported in 1877 and has been a problematic weed, especially in cereal-based systems, reducing crop yield and contaminating harvests (Smitchger et al, 2012;Adhikari et al, 2020a). In the PNW, specifics of diversification differ with the climatic zone (Douglas et al, 1992;Karimi et al, 2018).…”

“…In the PNW, A. cotula blooms from May to November, producing up to 200 conspicuous and attractive flower heads with white rays and yellow disc florets. Like many other asters (Rollin et al, 2016;Miller et al, 2018), it is self-incompatible (Kay, 1971), and the flowers are visited by a diverse suite of insects (Adhikari et al, 2020a). The traits such as abundant flower heads and long flowering periods of A. cotula might help attract and compete for pollinators maximizing its seed production.…”