Until recently, Ragweed tended to thrive on untended land, but now it is spreading even on cultivated soils. The Common Agricultural Policy, which instituted the fallow system, initially contributed thereby to the increase of Ragweed. However, this same policy prescribes the minimum upkeep of fallow zones to prevent weeds from becoming rampant, especially those harmful to public health such as Ambrosia. There are a series of regulations, from Parliament level down to local government level, from prevention to repression, designed to safeguard public health and hence to combat the proliferation of Ragweed.