Cost-effective cutting of Ambrosia artemisiifolia along roadsides
Ambrosia artemisiifolia (Asteraceae: EPPO List of Invasive Alien Plants) is commonly found along roadsides throughout Europe. These habitats aid seed dispersal along a linear corridor. Native to North America, A. artemisiifolia is now widespread across the EPPO region where its impacts include reduced yields in cereals and other field crops (for example sunflower). It can reduce fodder quality of meadows and pastures and can taint dairy products if cattle feed on it. In addition, its pollen can be strongly allergenic to humans (hay fever) and can cause dermatitis on contact with skin. To determine the cost-effectiveness of mowing regimes with varying frequency, population models were constructed where data on population parameters were included from four unmanaged populations across Europe and these data were integrated into the model along with the effects of four experimental mowing regimes along Austrian roadsides. The four experimental mowing regimes (plus an untreated control) were conducted over a five-year period at six locations in 2009 and varied in the cut timing (last week of June where vegetative growth was cut; last week of July – coinciding with peak male flowering; 3rd week of August – before peak female flowering, and 2nd week of September – before seed ripening) and frequency (i.e. mowing regimes were combined). In addition, seed burial experiments were conducted to obtain seed survival rates, and again these data were included in the population models. All cutting regimes reduced population growth rates compared to the unmanaged controls. Cutting during vegetative growth (June) and just before seed ripening (September) was the least effective method for reducing population growth rates. The efficacy of the two best cutting regimes was mainly due to cutting just before female flowering (August) as this decreased final adult plant height and reduced the final number of seeds produced. When mowing treatment costs were included into the model, the most effective low-cost treatment is a single cut before female flowering, however, if a budget for two cuts is available cutting before female flowering and before seed ripening was more cost effective than the one cut.
Sources
Lommen STE, Jongejans E, Leitsch-Vitalos M, Tokarska-Guzik B, Zalai M, Müller-Schärer H, Karrer G (2018) Time to cut: population models reveal how to mow invasive common ragweed cost-effectively. NeoBiota 39, 53-78.