Topics of interest and type of activities of the EWRS Working Group Weed Management in Mediterranean Cropping Systems: results of the questionnaire

Recientemente se ha producido una reestructuración de los grupos de trabajo de la Sociedad Europea de Malherbología (EWRS). Desde el nuevo grupo “Weed Management in Mediterranean Cropping Systems” en septiembre de 2023 se ha preparado un cuestionario para conocer el interés de potenciales participantes en cuanto a las prioridades temáticas, tipo de actividades y colaboración con otros grupos de trabajo. Hubo 54 respuestas de la EWRS, siendo 9 de España (ES). La SEMh (Sociedad Española de Malherbología) distribuyó el mismo cuestionario, obteniendo 20 respuestas adicionales, por lo que se recibieron 29 respuestas de personas vinculadas a este país. En cuanto a la temática, los participantes de otros países (OP) consideraron a las especies invasoras, el control de arvenses en regadío y el efecto del cambio climático sobre el manejo de malas hierbas como “muy relevante”, en un 56% de las respuestas. Mínimo laboreo y siembra directa obtuvieron un 51% y especies concretas un 49%. En cambio, los participantes de ES consideraron “muy relevante” el manejo de las malas hierbas en cultivos leñosos (en un 71%), la resistencia a herbicidas (68%) y el manejo de especies concretas (61%). En cuanto a las actividades, formar redes de trabajo (76% OP, 57% ES) y realizar webinars (71% OP, 61% ES) fueron las propuestas consideradas como más interesantes. En cuanto a la coordinación con otros grupos de trabajo, las preferencias fueron bastante diferentes para las personas de OP y de ES. Esperamos que gracias a estos resultados se puedan organizar actividades interesantes para la comunidad científica y técnica que trabaja en malherbología en esta zona climática.Recently, there has been a restructuring of the working groups of the European Weed Research Society (EWRS). The coordinators of the new group “Weed Management in Mediterranean Cropping Systems” have prepared in September 2023 a survey to find out the interest of potential participants in terms of thematic priorities, type of activities and collaboration with other working groups. There were 54 responses from the EWRS, with 9 from Spain (ES). The SEMh (Sociedad Española de Malherbología) distributed the same questionnaire, obtaining 20 additional responses, so 29 responses were received from people linked to this country. Regarding the topic, participants from other countries (OP) considered the invasive species, the control of weeds in irrigated lands and the effect of climate change on weed management as “very relevant” in 56% of the answers. Minimum tillage and direct sowing obtained 51% and specific species 49%. On the other hand, participants from ES considered “very relevant” weed management in woody crops (71%), herbicide resistance (68%) and the management of specific species (61%). Regarding activities, form work networks (76% OP, 57% ES) and organize webinars (71% OP, 61% ES) were considered most interesting proposals. Regarding coordination with other working groups, the preferences were quite different for people from OP and ES. We hope that thanks to these results, interesting activities can be organized for the scientific and technical community that work on weed science in this climatic zoneresource optimizationcoordinationdisseminationcollaborative workweed sciencePublishe

Current and future glyphosate use in European agriculture

There has been a longstanding and contentious debate about the future of glyphosate use in the European Union (EU). In November 2023, the European Commission approved the renewal of the use registration for glyphosate for a further 10 years. Nevertheless, the EU Farm to Fork strategy calls for a 50% reduction in pesticide use by 2030. In November 2022, the European Weed Research Society organised a 2 day workshop to identify critical glyphosate uses in current EU cropping systems and to review the availability of glyphosate alternatives. Workshop participants identified four current, critical uses in EU cropping systems; control and management of perennial weeds, weed control in conservation agriculture, vegetation management in tree and vine crops and herbicide resistance management. There are few herbicide alternatives that provide effective, economic, broad-spectrum control of weeds, particularly perennial weeds. Mechanical weed control, and in particular, soil cultivation is the most obvious glyphosate alternative. However, this is not possible in conservation agriculture systems and, in general, increased soil cultivation has negative impacts for soil health. Emerging technologies for precision weed control can enable more targeted use of glyphosate, greatly reducing use rates. These technologies also facilitate the use and development of alternative targeted physical weed control (e.g. tillage, lasers, electricity), reducing the energy and environmental costs of these approaches. In tree crops, the use of organic and inorganic mulches can reduce the need for glyphosate use. In general, reduced use of glyphosate will require an even greater focus on integrated weed management to reduce weed establishment in agroecosystems, increase weed management diversity and limit the use of alternative resistance-prone herbicides

Herbicide Resistance in Weed Management

Herbicides are the most efficient and cost-effective means of weed management [...

Effect of Herbicides on the Management of the Invasive Weed <i>Solanum rostratum</i> Dunal (Solanaceae)

Solanum rostratum Dunal is an invasive weed species that invaded Israel in the 1950s. The weed appears in several germination flashes, from early spring until late summer. Recently, an increase in its distribution range was observed, alongside the identification of new populations in the northern part of Israel. This study aimed to investigate the efficacy of herbicide application for the control of S. rostratum using two field populations originated from the Golan Heights and the Jezreel Valley. While minor differences in herbicide efficacy were recorded between populations, plant growth stage had a significant effect on herbicide response. Carfentrazone-ethyl was found to be highly effective in controlling plants at both early and late growth stages. Metribuzin, oxadiazon, oxyfluorfen and tembutrione showed reduced efficacy when applied at later growth stage (8–9 cm height), as compared to the application at an early growth stage (4–5 cm height). Tank mixes of oxadiazon and oxyfluorfen with different concentrations of surfactant improved later growth stage plant control. Taken together, our study highlights several herbicides that can improve weed control and may be used as chemical solutions alongside diversified crop rotation options. Thus, they may aid in preventing the spread and further buildup of S. rostratum field populations

Herbicide Resistance in Weed Management

Herbicides are the most efficient and cost-effective means of weed management [...

Recurrent Selection with Glufosinate at Low Rates Reduces the Susceptibility of a Lolium perenne ssp. multiflorum Population to Glufosinate

Repeated applications of herbicides at the labelled rates have often resulted in the selection and evolution of herbicide-resistant weeds capable of surviving the labelled and higher rates in subsequent generations. However, the evolutionary outcomes of recurrent herbicide selection at low rates are far less understood. In this study of a herbicide-susceptible population of Lolium perenne ssp. multiflorum, we assessed the potential for low glufosinate rates to select for reduced susceptibility to the herbicide, and cross-resistance to herbicides with other modes of action. Reduced susceptibility to glufosinate was detected in progeny in comparison with the parental population following three rounds of selection at low glufosinate rates. Differences were mainly observed at the 0.5X, 0.75X, and 1X rates. Comparing the parental susceptible population and progeny from the second and third selection cycle, the percentage of surviving plants increased to values of LD50 (1.31 and 1.16, respectively) and LD90 (1.36 and 1.26, respectively). When treated with three alternative herbicides (glyphosate, paraquat, and sethoxydim), no plants of either the parental or successive progeny populations survived treatment with 0.75X or higher rates of these herbicides. The results of this study provide clear evidence that reduced susceptibility to glufosinate can evolve in weed populations following repeated applications of glufosinate at low herbicide rates. However, the magnitude of increases in resistance levels over three generations of recurrent low-rate glufosinate selection observed is relatively low compared with higher levels of resistance observed in response to low-rate selection with other herbicides (three fold and more)

Sex dimorphism in dioecious Palmer amaranth (Amaranthus palmeri) in response to water stress.

Main conclusionPhenological isolation can potentially reduce seed output and may be exploited as a novel tool for ecological management of dioecious weeds. Dioecious plants may benefit from a maximized outcrossing and optimal sex-specific resource allocation; however, this breeding system may also be exploited for weed management. Seed production in dioecious species is contingent upon the co-occurrence and co-flowering of the two genders and can be further disturbed by flowering asynchrony. We explored dimorphism in secondary sex characters in Amaranthus palmeri, and tested if reproductive synchrony can be affected by water stress. We have used seeds of A. palmeri from California, Kansas and Texas, and studied secondary sex characters under natural conditions and in response to water stress. Seeds of A. palmeri from California (CA) and Kansas (KS) were cordially provided by Dr. Anil Shrestha (California State University, Fresno, California) and Dr. Dallas E. Peterson (Kansas State University, Manhattan, Kansas), respectively. Seeds of a third population were collected from mature plants (about 30 plants) from a set-aside field in College Station, Texas. A. palmeri showed no sexual dimorphism with regard to the timing of emergence, plant height, and relative growth rate. While the initiation of flowering occurred earlier in males than females, females preceded males in timing of anthesis. Water stress delayed anthesis in males to a greater extent than females increasing the anthesis mismatch between the two sexes by seven days. Our data provide the first evidence of environment-controlled flowering asynchrony in A. palmeri. From a practical point of view, phenological isolation can potentially reduce seed output and may be exploited as a novel tool for ecological management of dioecious weeds