6533b857fe1ef96bd12b4c64

RESEARCH PRODUCT

Gérer l’ambroisie à feuilles d’armoise en agriculture biologique

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Managing common ragweed in organic agriculture Common ragweed (Ambrosia artemisiifolia L.) is an invasive plant native to North America, capable of developing rapidly in many environments: agricultural fields, roadsides, construction sites, wastelands, riverbanks. Pollen, emitted at the end of summer, causes strong allergic reactions in sensitive people (rhinitis, asthma, etc.). It is also a threat to agriculture, as this annual plant can cause significant yield losses if it is not controlled. A study was conducted to analyze the practices of organic farmers in arable crop systems to control ragweed, as well as their level of knowledge of this plant according to their location. The results of this work show that ragweed is managed in organic farming by combining preventive and curative practices commonly used in this production method to control summer weed flora: diversified rotation, insertion of alfalfa, observation of plots, cleaning of the surroundings and seeds, stubble cultivation, false seeding, mechanical weeding in cultivation. The specificity of ambrosia management, given its high capacity for expansion, lies in increased surveillance and necessarily enhanced prevention. The solutions to control it can thus go as far as drastically reducing the return of favourable crops - sunflower, maize, soybean - in the rotation, or even manual weeding. Analysing the alternative management methods used in organic farming is interesting, to see how to optimise their mobilisation by organic farmers in regions differently affected by ragweed, in particular newly affected regions, but also to transpose them into a conventional system in a context of reduced use of plant protection products.