Fine‐tuning of a mowing regime, a method for the management of the invasive plant, Ambrosia artemisiifolia, at different population densities

Abstract

Common ragweed (Ambrosia artemisiifolia) is an invasive annual plant with highly allergenic pollen. Its spread in introduced and native ranges often occurs on roadsides, where it builds stable and rapidly growing populations. The most sustainable way of controlling the population size of this species is to prevent seed production in order to deplete the soil seed bank. Populations on roadsides are submitted to regular mowing management, which can even exacerbate the situation by inducing resprouting after cutting or by accidentally spreading seeds along the road. The population density in the juvenile stages of development could play an important role in the success of cutting regimes, as it might influence the resprouting capacity of this plant. The influence of the juvenile population density and of seven cutting regimes, differing in the timing and frequency of cuts, on easily measurable reproductive traits was investigated in a glasshouse experiment. The cutting regimes had a strong influence on the reproductive success and on the phenology of the development stages of ragweed. The population density in the juvenile stages did not play a role in further phenological development, but did influence the reproductive traits. The reproduction of ragweed can be lowered by locally adapted combinations of the timing and frequency of mowing. As the optimal management option for the reduction of both the male and female flowers, the authors suggest a first cut just before the start of male flowering, followed by subsequent cuts every 3-4 weeks.

The influence of mowing regime on the soil seed bank of the invasive plant Ambrosia artemisiifolia L.

“…Regrowth of ragweed after mowing is well-documented (Barbour and Meade 1981, Bohren et al 2005, Bohren et al 2008, Meiss et al 2008, Karrer et al 2011, Patracchini et al 2011, Simard and Benoit 2011, Tokarska-Guzik et al 2011) and varies with season (Milakovic et al 2014b). Timing and frequency of cutting has specific influences on the seed production of ragweed (Simard andBenoit 2011, Milakovic et al 2014a).…”

“…Therefore, aim of any sustainable long-term control of common ragweed should be a reduction of the soil seed bank in established populations. Milakovic et al (2014a and2014b) and Bohren et al (2008) found that seed production per plant could be influenced by carefully timed mowing. This study's goal is to test the effect of different cutting regimes applied for three years (Milakovic et al 2014a) on the quantity and quality of the ragweed soil seed bank.…”

Time to cut: population models reveal how to mow invasive common ragweed cost-effectively

“…Secondly, we do not, unfortunately, have field data on how mowing affects recruitment, sizes of new plants and plant survival of our species and hence, we did not include such effects in our models. Plant survival is unlikely to be directly affected much by mowing as our species has large capacity for re-growth, forming new lateral shoots when the main stem is cut (Bohren et al 2008;Kazinczi et al 2008;Milakovic et al 2014a). Such resprouting was even observed in 75-100% of plants cut two or three times (Milakovic et al 2014a;Patracchini et al 2011).…”

“…Plant survival is unlikely to be directly affected much by mowing as our species has large capacity for re-growth, forming new lateral shoots when the main stem is cut (Bohren et al 2008;Kazinczi et al 2008;Milakovic et al 2014a). Such resprouting was even observed in 75-100% of plants cut two or three times (Milakovic et al 2014a;Patracchini et al 2011). If mowing removes or weakens competitors, recruit-ment, survival and the size of new A. artemisiifolia plants may be promoted (Bazzaz 1979).…”

“…Cutting during vegetative growth (here in June) has a small effect on final plant height (here in September) and the direction of the effect varied with year. Indeed, the species is known for its large regrowth capacity (Barbour and Meade 1981) and compensatory growth after cutting in early summer was also found in other cutting experiments with A. artemisiifolia (Basky et al 2017;Bohren et al 2008;Milakovic et al 2014a). A single-cut regime at this time might, therefore, even lead to an increased r in some years.…”