Although ragweed (Ambrosia artemisiifolia) is a native plant, it is highly invasive. Indeed, ragweed is being found all over Southern Quebec while one hundred and fifty years ago, it occupied only a small part of it.
The Champ des Possibles (including Bernard lot) ended up with a huge infestation of ragweed in 2016 despite having Les Amis du Champ des Possibles expend major efforts in planting competing species over the years in addition to proceeding with localized annual mowings or weedings, measures usually considered sufficient to control ragweed.
This infestation was jeopardizing the possibility of conserving the pastoral aspect of the field as well as its mission of supporting biodiversity. In fact, ragweed is responsible for severe allergies and asthma problems. Since young children from an outdoor day care center frequent this place daily, it would have been irresponsible to let them breathe in so much pollen. In addition, ragweed showing allelopathic behavior, its presence affects the establishment of other plants.
Rather than responding to the need to remove pollen from the air by a fieldwide mowing, Irene Mayer proposed a pilot project to test her method of selective weeding in order to reconcile public health protection with the support of biodiversity.
The project aims to demonstrate that ragweed can be successfully eradicated in a field-like urban park while returning to conditions that support biodiversity. The 3×3 OUT! protocol (3 selective weedings, 3 successive summers and autumns) was conceived after years of experimentation in Montreal’s streets and alleyways.