Landscape perspectives for agroecological weed management. A review

The current research effort on agroecological weed management is largely rooted in agronomy and field-scale farming practices. This article reviews current knowledge of landscape effects on weed communities and seed predation. The ecological processes underlying landscape effects, their interaction with in-field approaches, and the implications of landscape-scale change for agroecological weed management are discussed.

Boinot, S., Alignier, A. & Storkey, J. Landscape perspectives for agroecological weed management. A review. Agron. Sustain. Dev. 44, 7 (2024).

Control rather than eradicate weeds

Picture copyright Rothamsted Research

The intensive use of herbicides and tillage to eradicate weeds from fields leads over time to biodiversity loss, soil erosion, health risks, and herbicide resistance. In a recent review, researchers MacLaren et al. suggest to regulate rather than eradicate weeds, in order to suppress problematic weeds while fostering weed diversity, able to sustain ecosystem services. This could be achieved by reducing the intensity of weed control, but increasing the strategic use of the crop, livestock, nutrient, and management diversity on farms.

Using a roller crimper for weed management in organic vegetable production

Picture copyright Navarro-Miró et al.

Based on seven trials from five countries across Europe over two years, scientists Navarro-Miró et al. showed the effectiveness of roller crimper for controlling weeds at the early stages of crop growth in different vegetable systems, soils and climatic conditions. Most importantly, they found that the use of roller crimper can reduce the reliance on tillage for weed management in organic vegetable systems.

Diversifying grain-based cropping systems for a sustainable agriculture

Picture copyright Adeux et al.

Herbicides jeopardize the sustainability of agriculture. Unfortunately, no alternative weed management tool can level with their efficacy. Based on 17-years of observations, Scientists Adeux et al. showed that diversified crop rotation allowed low herbicide use, long-term weed management, and high productivity in grain-based cropping.

Cultivating globe artichoke and cardoon to prevent weeds in Mediterranean rotations

Picture copyright AH Cain, Inra

Weeds represent one of the most important pests in agroecosystems. Recently, scientists Scavo et al. found that globe artichoke, cultivated and wild cardoon significantly reduced the number of seeds in the soil thanks to their allelopathic activity. They also observed a positive effect on some bacteria involved in the soil N-cycle. The introduction of these species in Mediterranean crop rotations could hence decrease the utilization of synthetic herbicides.

Air-propelled agricultural residues kill weeds

Picture copyright Perez-Ruiz et al.

Crop production often results in abundant agricultural residues, and organic crop production suffers from an overabundance of weeds. Scientists Perez-Ruiz et al. recently showed that several gritty-textured residues, particularly those derived from maize cobs and olive pits, could abrade weed seedlings when propelled by air. Their use can contribute to the non-chemical control of weeds requested by organic farming and offers a potential solution to address herbicide-resistant weeds.

95% less herbicides in maize using improved drone imagery to locate weeds

Picture copyright López-Granados et al.

Johnsongrass, one of the most competitive weeds in maize, is actually controlled by broadcast application of at least two herbicide treatment. Agronomists López-Granados et al. designed a high-resolution method to locate weeds using drones to take visible and near infrared pictures, then algorithms to map johnsongrass patches (light green) in maize rows (dark blue). They deduce that site-specific control would save up to 95% herbicides, which will be consistent with European and the Spanish legislations.

Weeds to reduce nitrogen pollution

Picture copyright WORTMAN

Cover crops reduce nitrogen pollution from croplands, but naturally occurring weeds may provide similar benefits during fallow periods. Agronomist Wortman shows that nitrogen loss is 60% lower in weedy fields than in bare fields. Cover crops are 26% more effective than weeds in reducing nitrogen loss, but given the issues of cover crop adoption, cultivation of fallow weeds looks promising.

Crops adapted to climate change and weed competition

Picture copyright KORRES

Crop yield depends on atmospheric CO2 levels, temperature, drought and competition with weeds. There is therefore a need to forecast which plant traits are important to sustain yield under a changing climate. Agronomists Korres et al. review the effect of climate on crops and weeds to disclose resilient plant traits and cultivars.

Weeds are good for agriculture, yes they are!

Picture copyright Hanzlik and Gerowitt

In industrial agriculture weeds have been considered solely as undesired plant species that should be removed with pesticides. Now scientists have found that weeds could help farming by, e.g., pollination, preventing water and soil runoff, and attracting predators of crop pests. There is therefore a need of weed surveys across Europe. Agronomists Gerovitt and Hanzlik reviewed the methods of weed surveying in 43 surveys, mainly in Europe, covering up to 4423 fields.