Common ragweed in Switzerland: distribution and control

Ragweed (Ambrosia artemisiifolia L.) is presently raising a growing worry in Switzerland. Beside being a weed in arable field, the plant produce a very allergenic pollen that can induce potentially important health problems in the population. This situation require the application of a strong control strategy that concern, beside agriculture, the staffs in charge of the management of natural areas as well as those managing road sides, building- and gravel industries. This paper presents briefly the biology of the plant as well as its means of propagation. It also presents the weed control strategies applicable in agriculture, especially during the fallow time. First observations concerning seeds development indicate that with a unique treatment, carried out at the right time at the end of the season, it should be possible the break the cycle of the plant and so limit its propagation in our country.