Abstract 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.

Appropriate weed control measures during the renewal phase of temporary grasslands are critical to ensure high yields during the whole grassland lifecycle. The aim of this study was to determine which integrated grassland renewal strategy can most effectively control annual weeds in the sowing year and delay perennial weed re-establishment. Four split-plot trials were established at three sites dominated by Rumex spp. along a south-north gradient in Norway. The annual and perennial weed abundance was recorded during the sowing year and two or three production years. Main plots tested seven renewal strategies: 1. Spring plowing, 2. Spring plowing+companion crop (CC), 3. Summer cut+plowing, 4. Summer glyphosate+plowing, 5. Summer glyphosate+harrowing, 6. Late spring glyphosate+plowing, 7. Fall glyphosate+spring plowing+CC. Strategies 1–4 were tested in all four trials, strategy 5 in three trials, strategy 6 in two trials and strategy 7 in one trial. Plowing was performed at 20–25 cm depth, rotary harrowing at 15 cm depth, and glyphosate was applied at 2160 g a.i. ha-1. CC was spring barley (Hordeum vulgare). Subplots tested selective herbicide spraying (yes/no) in the sowing year. Results showed that effects of renewal strategies were often site-specific and differed between the sowing year and production years. Spring renewal resulted in higher perennial weed abundance than summer renewal in two out of four trials (by 3 and 12 percentage points, over all production years), and glyphosate followed by harrowing drastically increased Rumex spp. in one out of three trials (by 18 percentage points over all production years). CCs only significantly reduced perennial weed abundance in one trial (by 8 percentage points over all production years). In comparison, the selective herbicides had a strong effect on annual and perennial weeds in the sowing year in all trials. Selective herbicides reduced the weed cover from 32% to 7% cover, and averaged over the production years and sites, the perennial weed biomass fraction was 6 percentage points lower where herbicides had been applied. We conclude that while the tested renewal strategies provided variable and site-specific perennial weed control, selective herbicides were effective at controlling Rumex spp. and other perennial dicot weeds in the first two production years.

Elymus repens is a problematic perennial weed in annual crops, grasslands and leys. Rhizome fragmentation by vertical disking can potentially reduce E. repens abundance with minimal tillage, but data are lacking on its efficiency in forage production. In a two-year study (2017–2018, 2018–2019) conducted in two forage grass-clover leys that were mostly weed-free except for large E. repens populations, this study examined effects on forage yield, botanical composition, and E. repens rhizome biomass of rhizome fragmentation at significant growth initiation in spring (early rhizome fragmentation, ERF) and/or when conditions allowed after the first forage cut (late rhizome fragmentation, LRF). Cold, wet springs and hard, dry soil in summer delayed treatment in both treatment years, to late spring (ERF) and late summer/early autumn (LRF). In the treatment year, ERF reduced first-cut forage yield by 44% compared with no rhizome fragmentation, while LRF decreased second- and third-cut yield by 24% and 53%, respectively. In the year after treatment, ERF increased total forage yield by on average 10%, while LRF had no effect. Over both years, combined forage yield was reduced by 11% by ERF and 4% by LRF. Both treatments reduced E. repens rhizome biomass, but inconsistently (ERF by 25% in one year only, LRF by 24% at one of two sites). ERF reduced E. repens incidence in forage by 10% in the treatment year, but had no effect in the following year. Thus, rhizome fragmentation by vertical disking can reduce E. repens abundance in grass-clover leys, but the effect is inconsistent and forage yield can be impaired, especially in swards with much E. repens. Moreover, disking is hampered by hard, dry soil conditions.

Wool pellets from unutilized wool on Gotland – a development project with focus on the pelleting process

A large proportion of the wool produced in Sweden is discarded as it cannot be used by the textile industry. Before the wool can be used it must be collected and washed. However, a large quantity of low-quality wool is mixed in with the high-quality wool and thus enter the processing industry when the wool is collected. As it is not usable by the industry, this low-quality wool simply takes up space and lowers the processing speed as it must be separated from the high-quality wool and be discarded, lowering the economic output of the wool processing industry. However, unutilized wool has the potential to be used as a slow-acting fertilizer, soil amendment, or mulch for cultivation purposes. Pelleting is an attractive method of processing biomass into a product that is efficient and easy to handle, transport and use. Pellet presses are commercially available from small farm-scale to large-scale facilities. The aim of the project was to develop and adapt the pelleting technology to work with Swedish wool that cannot be used to produce yarns or other textiles. The goal was to develop methods and technology for pre-treating or disintegrate the wool, adapt the input and pelleting part of the pelleting process to work with low-quality wool and try to optimize the quality of the pellets. Furthermore, the goal was to analyze the plant nutrient value and strength of the pellets produced and create a packaging prototype. During the project, additional goals were added: to automate the process from pre-treatment to packaging as much as possible, and to use literature to determine if the pelletizing process is likely to be sufficient enough to hygenize the wool from weed seeds. An automated production line from wool to finished pellets has been built at Ullkontoret (Sweden’s only full-scale wool washing facility). Coarse and fine shredding, feeding and regulation of feed capacity function well, while the pelleting pressing does not work sufficiently well. Wool pelleting of only low-quality wool proved technologically challenging and neither the modified pellet presses nor the imported wool pellet press worked, despite modifications. In other European countries, this problem is solved by mixing in higher quality wool. Further technological development of wool pelleting is needed to obtain a system that can handle all types of low-quality Swedish wool. Literature studies and nutritional analyses confirm that wool pellets work well as a slow-acting fertilizer (often in mixture due to a very low phosphorus content), but the potential of wool as a soil amendment, mulch and snail repellent requires more studies. Pelleting is probably not enough to hygenize the wool from weed seeds. It is a challenge to produce a packaging that both meets the quality requirements of the product (e.g., maintain the right humidity, preventing odors) and at the same time meets the demands of the type of environmentally conscious consumer who is the main target group for a nature-based product.

Many herbaceous perennial plant species gain significant competitive advantages from their underground creeping storage and proliferation organs (CR), making them more likely to become successful weeds or invasive plants. To develop efficient control methods against such invasive or weedy creeping perennial plants, it is necessary to identify when the dry weight minimum of their CR (CR DWmin) occurs. Moreover, it is of interest to determine how the timing of CR DWmin differs in species with different light requirements at different light levels. The CR DWmin of Aegopodium podagraria, Elymus repens and Sonchus arvensis were studied in climate chambers under two light levels (100 and 250 ?mol m?2 s?1), and Reynoutria japonica, R. sachaliensis and R. ? bohemica under one light level (250 ?mol m?2 s?1). Under 250 ?mol m?2 s?1, the CR DWmin occurred before one fully developed leaf in R. sachaliensis, around 1?2 leaves in A. podagraria and E. repens and around four leaves in S. arvensis, R. japonica and R. ? bohemica. In addition to reducing growth in all species, less light resulted in a higher shoot mass fraction in E. repens and S. arvensis, but not A. podagraria; and it delayed the CR DWmin in E. repens, but not S. arvensis. Only 65% of planted A. podagragra rhizomes produced shoots. Beyond the CR DWmin, Reynoutria spp. reinvested in their old CR, while the other species primarily produced new CR. We conclude that A. podagraria, R. sachaliensis and E. repens are vulnerable to control efforts at an earlier developmental stage than S. arvensis, R. japonica and R. bohemica.

Couch grass (Elymus repens) is a morphologically diverse, rhizomatous, perennial grass thatis a problematic weed in a wide range of crops. It is generally controlled by glyphosate or intensivetillage in the intercrop period, or selective herbicides in non-susceptible crops. The aim of this reviewis to determine the ecacy of non-chemical strategies for E. repens control. The review shows thatindirect control measures like crop choice, subsidiary crops, and fertilizer regimes influence E. repensabundance, but usually cannot control E. repens. Defoliation (e.g., mowing) can control E. repensgrowth, but ecacy varies between clones, seasons, and defoliation frequencies. Tillage in theintercrop period is still the main direct non-chemical control method for E. repens and its ecacy canbe increased, and negative side-eects minimized by an appropriate tillage strategy. Some new tillageimplements are on the market (Kvik-up type machines) or under development (root/rhizome cutters).Alternative methods that can kill E. repens rhizomes (e.g., steaming, soil solarization, biofumigation,hot water, flooding) often have high costs or time requirements. More studies on the eect of croppingsystem approaches on E. repens and other perennial weeds are needed.