Search results for "weed"

Non-target-site-based resistance to herbicides: what do we know, and how can we know more?

2013

Non-target-site-based resistance (NTSR) includes all types of mechanisms conferring resistance to herbicides that do not involve modifications at the herbicide target site. NTSR can be the most widespread type of resistance in a weed species, especially in grasses. NTSR can confer resistance to herbicides with different modes of action. Despite the threat it sets upon chemical weed control, NTSR is still the dark side of resistance to herbicides. In particular, NTSR genetics is poorly known. As a consequence, there are no quick, molecular-based, NTSR diagnostic tools, which hampers the development of tactics aiming at delaying NTSR selection in the field. The lack of data regarding NTSR gen…

Stock de semences versus relevé de flore : comment mesurer les évolutions de la flore adventice liées à des modifications de systèmes de culture ?

2019

Le suivi des changements de la composition adventice est une préoccupation majeure lors de la mise en place de nouveaux systèmes de culture. Il se pose toutefois des questions sur la méthodologie à mettre en place pour ce type de travail. L’étude du stock de semences qui représente en théorie la flore potentielle, semble s’imposer comme la façon la plus évidente de caractériser les communautés de mauvaises herbes. Toutefois cette méthode est lourde à mettre en place et nécessite un nombre d’échantillons important. La flore adventice d’une centaine de parcelles conduites en semis direct sous couvert a été étudiée au travers de deux méthodes : un relevé de flore réalisé au printemps et un éch…

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

2019

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 …

Reduction of nitrate leaching: what is the contribution of the residual weed flora?

2018

International audience; Integrated crop protection tolerates residual weeds if they are not harmful for crop production. Weeds are often solely considered as a pest, causing crop yield loss, harvest pollution, diseases … However, they may also provide beneficial services for agroecosystems, promoting plant biodiversity and feeding other organisms potentially beneficial to crop production (pollinators, carabids…). The role of residual weed flora as nitrate catchers, during summer fallow, has however rarely been assessed. Yet, some weed species are known for their high potential to take up soil nitrogen. The present study aimed to (1) develop an indicator to account for the potential benefici…

Evolution des problèmes malherbologiques à l’adoption du semis direct sous couvert

2019

Le semis direct sous couvert regroupe un ensemble de pratiques appliquées simultanément en vue de répondre à trois principes : réduction totale du travail du sol, couverture optimale des sols et diversification de la succession culturale. Cette approche représente, en France, une stratégie innovante qui semble convaincre de plus en plus d’agriculteurs. En se privant du travail du sol, la gestion des adventices en semis direct sous couvert devient plus complexe, ce qui limite l’adoption généralisée du semis direct sous couvert. Afin d’éclairer les problèmes malherbologiques rencontrés en semis direct sous couvert, un questionnaire en ligne à destination des agriculteurs a été diffusée en Fra…

Editorial Highlight. Discover Cambridge. Will frost-resistant weeds benefit from climate change ? About The paper ‘Relative success of frost-resistan…

2021

Gestion des adventices dans un contexte de réduction des intrants de synthèse

2018

How to model crop-weed competition for soil resources: Connecting the STICS soil submodel to the FLORSYS weed dynamics model

2020

International audience

Trait distribution within winter wheat fields can partly be explained by disturbances and competition for resources

2013

International audience; Weed species are not homogeneously distributed into field elements (Cordeau et al. 2012)*.In a field, weed species are mainly competing with the crop and constrained by management practice (i.e.disturbances). In the crop edge, less unfavorable conditions for weed development (i.e.absence of direct crop competition,l ess frequent disturbances could explain the greater diversity of weeds.To understand this observation, a functional approach base dont raits known to respond both to disturbances and to competitive or facilitative interactions can be used.Our assumptions are that(i)the crop edge is likely to all owawi derrange of ecological strategies thus promoting speci…

Échantillonnage adaptatif optimal dans les champs de Markov, application à l’échantillonnage d’une espèce adventice

2012

This work is divided into two parts: (i) the theoretical study of the problem of adaptive sampling in Markov Random Fields (MRF) and (ii) the modeling of the problem of weed sampling in a crop field and the design of adaptive sampling strategies for this problem. For the first point, we first modeled the problem of finding an optimal sampling strategy as a finite horizon Markov Decision Process (MDP). Then, we proposed a generic algorithm for computing an approximate solution to any finite horizon MDP with known model. This algorithm, called Least-Squared Dynamic Programming (LSDP), combines the concepts of dynamic programming and reinforcement learning. It was then adapted to compute adapt…