During the past century, common ragweed has spread from its native eastern North America
to Europe, where it has become an increasing problem from both an agricultural and a
human health perspective. Two field experiments were performed over a 2-yr period in a
naturally infested fallow field in northern Italy to evaluate the effects of common ragweed
plant density on its growth dynamics and to study its response to clipping. In the first
experiment, three plant densities were tested (4, 12.5, and 25 plants m− 2) and plant height …