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Herbicide volatility and drift are serious problems for chemical weed control. The extended use of dicamba, especially due to the commercial release of dicamba-resistant crops, revealed many off-target dicamba injury issues for sensitive crops. The objective of the present study is to give information on the chemical properties and volatility of dicamba and highlight some key issues, while a systematic review of the recently reported cases is attempted. Unfortunately, the problem is increasing, with a huge majority of the injuries reported in the USA, but it is also present in many other countries. Several arable, horticultural, and perennial crops suffer from such damage. Specific measures and approaches are suggested in order to quantify, reduce, and prevent such problems, while the training of farmers and stakeholders and further research are certainly required for the optimization of the several alternative options.

Sustainable crop and weed management is among the crucial challenges in the era of the EU Green Deal. The main objective of the present study was to apply an innovative approach for the rapid assessment of herbicide efficacy in maize (Zea mays) crop in four different trials during two years. Weed NDVI values were recorded at two weeks after treatment, while weed biomass and crop yield were also measured. The results revealed significant differences between the several treatments. In many cases, significant effects of herbicide application on the normalized difference vegetation index (NDVI) values and weed biomass were noticed at two weeks after treatment. Moreover, the mixture nicosulfuron + rimsulfuron + mesotrione resulted in high efficacy on the crop yield of all fields. Consequently, our approach can allow for an early prediction of the real field efficacy of several herbicides and thus act as an alert for the farmers in order to choose the most efficient herbicide, avoid applications of low efficacy and reduce the herbicide inputs.

Field trials were conducted (2022–2023) in a randomized complete block design to evaluate the combined use of a microbial biostimulant, P-K Stim, which contains phosphate and potassium solubilizing bacteria (109 Colony Forming Units mL−1), various fertilization rates, and herbicide use on weed growth and the productivity of alfalfa (Medicago sativa L.), oilseed rape (Brassica napus L.), and durum wheat (Triticum durum Desf.). The following treatment list was the same on all trial fields: (1) 100% basal fertilization (100N), (2) 20% basal fertilization and application of microbial biostimulant P-K Stim (20N + PK), (3) 100% basal fertilization and post-emergence herbicide treatment (100N + H), (4) 20% basal fertilization together with the application of P-K Stim and a post-emergence herbicide treatment (20N + PK + H), and (5) 50% basal fertilization together with the application of P-K Stim and a post-emergence herbicide treatment (50N + PK + H). The combined use of fertilization, biostimulants, and herbicides significantly affected crop yield, its components and weed biomass (p ≤ 0.05). The concentrations for potassium and phosphorus were higher in the 20N + PK + H and 50N + PK + H treatments for all crops compared to other treatments. Nutrient concentrations were remarkably high across all crops, closely approximating the values of the recommended nitrogen fertilization. Crop yield and its components were positively influenced by the 20N + PK + H and 50N + PK + H treatments. Weed biomass was significantly lower in these plots compared to other treatments.

Recently, there has been growing interest in the use of summer cover crops that can be grown during summer fallow periods of crop rotation. This study evaluates the potential of sunn hemp (Crotalaria juncea L.), velvetbean [Mucuna pruriens (L.) DC.] and cowpea [Vigna unguiculata (L.) Walp.]. as three annual legumes summer cover crops. The main objective of this review was to conduct global research comparing these summer cover crops to investigate the benefits, challenges, and trade-offs among ecosystems services when implementing these summer cover crops. In European agriculture, there are three main windows in crop rotation when these summer legumes can be grown: Around mid-spring after winter fallow, early summer after harvest of a winter crop, and mid- to late summer after harvest of an early-season crop. All three legumes can suppress weeds while they are actively growing. After termination, their mulch can create unfavorable conditions for weed emergence. Sunn hemp and velvetbean cover crops can cause a reduction in weed biomass of more than 50%. In addition to their ability to suppress weeds, sunn hemp, velvetbean, and cowpea provide a variety of ecosystem services, such as improving soil health, quality, and fertility, controlling pests, and sequestering carbon. The review highlights their promising role in weed suppression and their contribution to sustainable agricultural practices. However, further research is needed to evaluate their performance in weed management and their environmental impact in field trials under different soil-climatic conditions, as cover cropping is an effective practice but highly context-specific.

Horseweed (C. canadensis) and fleabane (C. sumatrensis) are two annual or perennial herbaceous weeds present with high frequency and density in many parts of the world. Their response to water deficit was studied by means of seed germination tests and pot experiments. Seed germination was tested in solutions with different concentrations of polyethylene glycol (PEG). Two biotypes of each species were examined, one glyphosate resistant and the other susceptible. Growth responses were similar in the two species, both being more affected by lower (−1 MPa) than higher water potential (−0.2 MPa). The results revealed a significant effect of the biotype and the weed species on the drought stress response and adaptation. When high PEG concentrations were applied (−0.6 MPa), both C. sumatrensis biotypes had higher germination percentages (up to 88%) than the C. canadensis biotypes, while in most cases the seeds of the resistant biotypes germinated more (up to 72%) compared to the susceptible ones. These findings were confirmed by means of NDVI values, indicating that remote sensing can be used for a quick evaluation of the drought stress response of these weeds. The results obtained highlight the significant effect of species, biotypes and drought stress level on the germination, survival and growth of the weeds.

The European Union takes the sustainability of pesticide use into serious account, and one of the main challenges of the EU Green Deal is the significant reduction in chemical control [...]

A field trial was conducted (2020–2021) in a randomized complete block design arranged according to the split-plot design to evaluate the integrated effects of an alternative fertilization practice based on the application of a microbial biostimulant in combination with different weed control methods on weed growth and maize productivity. Two fertilization practices, conventional (CF) and alternative (AF), formed the main plots. The CF supplied maize with 160 kg N ha−1. The AF included a foliar application of the biostimulant NitroStim®, which contains N2-fixing bacteria (1 × 1012 colony forming units; CFU L−1) along with a 50% lower fertilizer incorporation rate (80 kg N ha−1). Four weed control treatments formed the subplots: one inter-row mechanical cultivation (M1), two inter-row mechanical cultivations (M2), tembotrione application (99 g a.i. ha−1; H), and an untreated control (CON). Combined over the years (p ≥ 0.05), fertilization, weed control, and their interactions affected (p ≤ 0.05) weed density and biomass, maize grain yield, and nitrogen partial factor productivity (PFPN). The AF reduced weed biomass by 28% compared to the CF. M1 resulted in a high value (389 g m−2). M2 and H reduced weed biomass compared to (M1 ≥ 70%). Weed biomass dropped below 35 g m−2 in the AF × H and AF × M2 subplots. Observations on weed density were similar. The AF resulted in 12 and 56% higher maize grain yield and PFPN than the CF, respectively. M2 increased grain yield by 18 and 25% compared to M1 and CON, respectively, and was not different from H. Moreover, AF × H and AF × M2 were the highest-yielding interactions (≥12,000 kg grain ha−1). AF × M2 increased PFPN by 56, 58, 64, and 67% compared to CF × H, CF × M2, CF × M1, and CF × CON, respectively, while AF × H resulted in similar PFPN.

Hot foam applications represent a new, smart concept in the field of thermal weed control. The aim of this study was to evaluate the efficacy of hot foam and other weed control methods in two olive groves in southern Greece (Pyrgos and Kalamata). The experiment was laid out in a randomized complete block design (RCBD) with six treatments and three replicates. Treatments were applied in the areas between trees, in the row and included mowing with a disc–flail mower, mulching with pruning residues (2.65 kg m–2), glyphosate (at 1,440 g a.e. ha–1), hot foam (13.33 L m–2), pelargonic acid (at 1,088 g a.i. ha–1; twice), and an untreated control. Two experimental runs were conducted at each site using the same treatment list. Malva parviflora L. and Sinapis arvensis L. were the predominant weeds in Pyrgos, while Urtica urens L., Galium aparine L., and Parietaria officinalis L. dominated in Kalamata. Site–experimental runs and treatments significantly affected NDVI and weed biomass (P–Value ≤ 0.001). Hot foam reduced weed biomass by up to 81, 88, 90, and 96% compared to mulching, mowing, pelargonic acid, and the untreated control, respectively. This treatment also reduced M. parviflora biomass by 75–88 and 92–93% compared to mowing and pelargonic acid, respectively, in Pyrgos and P. officinalis biomass by more than 80% in Kalamata compared to the above treatments. In all site–experimental runs, hot foam and glyphosate resulted in the lowest NDVI and weed biomass. The overall performance of hot foam was comparable to glyphosate, suggesting that this method is an environmentally friendly and effective, alternative method to control weeds in olive groves. Further research is required to optimize the use of hot foam for weed control in more perennial crops and under different soil and climatic conditions.

Maize is an important staple crop and a significant source of various nutrients. We aimed to determine the macronutrients, antioxidants, and essential elements in maize genotypes (white, yellow, and red kernel) using three different fertilizers, which could be used as a basis to increase the nutrient density of maize. The fertilizer treatments used bio- and organic fertilizers as a sustainable approach, urea, as a commonly used mineral fertilizer, and the control (no fertilization). We evaluated the yield, concentration of macronutrient (protein, oil, and starch), nonenzymatic antioxidants (phenolics, yellow pigment, total glutathione (GSH), and phytic phosphorus), and reduction capacity of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, as well as essential elements that are commonly deficient in the diet (Mg, Ca, Fe, Mn, Zn, Cu, and S) and their relationships with phytic acid. The genotype expressed the strongest effect on the variability of grain yield and the analyzed grain constituents. The red-kernel hybrid showed the greatest accumulation of protein, oil, phenolics, and essential elements (Ca, Fe, Cu, and S) than a yellow and white hybrid, especially in the biofertilizer treatment. The yellow kernel had the highest concentrations of yellow pigment, GSH, phytic phosphorous, Mg, Mn, and Zn (19.61 µg g−1, 1,134 nmol g−1, 2.63 mg g−1, 1,963 µg g−1, 11.7 µg g−1, and 33.9 µg g−1, respectively). The white kernel had a greater starch concentration (2.5% higher than that in the red hybrid) and the potential bioavailability of essential metals, particularly under no fertilization. This supports the significance of white maize as a staple food in many traditional diets across the world. Urea was important for the enhancement of the antioxidant status (with 88.0% reduction capacity for the DPPH radical) and increased potential Zn bioavailability in the maize kernels (13.3% higher than that in the biofertilizer treatment). This study underlines the differences in the yield potential and chemical composition of red, yellow, and white-kernel maize and their importance as a necessary part of a sustainable human diet. This information can help determine the most appropriate genotype based on the antioxidants and/or essential elements targeted for kernel improvement.

Allelopathic effects of various plants can be exploited for use against weeds; however, the selectivity in different crops is also important. In the current study, the effects of lemon balm (Melissa officinalis) allelochemicals on seed germination and seedling emergence of three biomass crops and three legume species were evaluated. Seed germination of rapeseed was reduced by 19, 30, 56, and 80% in the concentrations of 1, 2, 5 and 10%, respectively, as compared to the control group, whereas sweet sorghum seeds showed a more intermediate response and sunflower germination was affected only by the highest concentration. Seed germination of common bean was by 25, 34 and 60% lower at 1, 2 and 5% extract concentrations, respectively, in comparison to the control whereas up to 85% reduction of seed germination was recorded in 10% concentration. Peanut seed germination percentage ranged between 72 and 47% of control in 5 and 10% concentrations, respectively, while soybean germination was least affected from M. officinalis leaf extracts since it was reduced by only 25 and 41% in 5 and 10% concentrations, respectively, as compared to the control. Seedling emergence of rapeseed was reduced by 14, 25, 46, and 79% in the concentrations of 1, 2, 5 and 10%, respectively, as compared to the control whereas lemon balm extracts showed increased selectivity on the sunflower. Soybean emergence was reduced by only 27 and 46% in 5 and 10% concentrations, respectively, in comparison to the control whereas common bean’s seedling emergence was reduced up to 35% even in 2% concentration. Allelopathic response index values confirmed that sunflower and rapeseed were the least and most sensitive biomass crops to lemon balm allelochemicals, respectively, whereas sweet sorghum showed an intermediate response. Increased was the selectivity of the aqueous leaf extracts on soybean, whereas seed germination and seedling emergence of peanut were more affected and common bean was the most sensitive crop. Further research is needed to investigate the selectivity of M. officinalis and other aromatic plants’ allelochemicals on various crops and under different soil and climatic conditions to optimize their efficacy as tools of more eco-friendly weed management strategies.

The extended and in many cases unjustified use of herbicides has resulted in herbicide resistance development and serious environmental concerns. Therefore, the need for implementation and wider adoption of several agronomic and cultural practices is imperative. Ecologically-based crop management practices like crop rotation, intercropping, delay of sowing date and increased crop density can be also the basis for effective and sustainable weed management. In the present review, several cases are presented and the key points of each method are discussed. Special attention is given to the fact that the efficacy of each practice is depended on the specific soil and climatic conditions along with the field history of each site and crop. Alternative methods of weed management should be further studied and optimized to include them in both organic and conventional production systems and ensure the sustainability of agroecosystems.

The effects of aqueous extracts of the aromatic plant Melissa officinalis were studied on the seed germination and early seedlings growth of ten summer annual species in Petri dish bioassays and pot experiments. The in vitro experiments on the aqueous extracts from M. officinalis on seed germination shows that the extracts of 5 and 10% were the most active inhibitors for all the studied weed species. Seed germination reduction by the aqueous extracts was up to 54% of the untreated seed lot for each species. On the contrary, the concentration of 1% resulted in germination reduction ranging from 1 to 11%, while in some of the weed species (P. minor, S. nigrum, P. angulata and C. albida) the effect was rather stimulatory. This finding is in full agreement with "novel weapons hypothesis" and supports that native plants compared with invasive (like C. albida and P. angulata) are affected more due to the absence of tolerance or resistance to the allelochemicals. The allelopathy RI of aqueous extracts of lemon balm was negative in most cases, while in the case of 10% concentration, emergence was reduced by 58, 54, 48, 46 and 43% for X. strumarium, C. album, S. faberi, C. canadensis and C. bonariensis, respectively. The allelopathic activity of M. officinalis could be exploited in future studies, to identify and isolate the allelochemicals, as models for future herbicides for integrated weed management.

Helichrysum amorginum is a perennial shrub, endemic on the Greek island of Amorgos and used for medicinal, cosmetic and ornamental purposes. Information concerning germination behavior and seedling survival is considered essential for the establishment and cultivation of wild species. The objective of this study was to investigate the effect of temperature and light on germination of Helichrysum amorginum seeds. A set of experiments was conducted under completely randomized design with four replications of 200 seeds at three different suboptimal germination temperatures (15, 20 and 25°C) in light and dark conditions for 10 days. Seed material was collected from two different fields of the island (Aegiali and Katapola). The germination performance was evaluated by final germination percentage and mean germination time. The effect of temperature on seed germination percentage and mean germination time was significant in all cases. The presence of light enhanced germination, especially at the optimum temperature of 20°C. In most cases the mean germination time increased at the lower temperature of 15°C. Seeds from Aegiali exhibited higher germination ability than the seed lot from Katapola. Knowledge of seed germination behaviour is of major importance in order to establish effective protocols for seed propagation in Helichrysum amorginum.

Barnyardgrass (Echinochloa crus-galli) is one of the most problematic weeds on rice crop. The research was to evaluate the response of several barnyardgrass biotypes from Greece to profoxydim and evaluate the role of different rates and growth stages on the overall effectiveness. Three experiments were conducted in 2018. The response of the several biotypes had high variability (20-100%), with the most susceptible biotypes originating from regions in which crop rotation is a common practice (Fthiotida). Moreover, dose-response experiments showed that the rate of profoxydim required to adequately control the resistant population G17 was 4-times higher than the maximum recommended dose. Concerning the phenology effect on profoxydim effectiveness, This study revealed a higher efficacy at the earlier growth stage BBCH 13 (15-50% higher than growth stages BBCH 22 and 30), probably it was due to the smaller size and the higher growth rate of the younger plants. Consequently, the significant effect of weed growth stage on the effectiveness of profoxydim implies that application of the herbicide at earlier growth stages could optimize herbicide use and result in a better control with the condition of avoidance crop injuries.

Precision agriculture (PA) practices based on the use of sensors and vegetation indices have great potential for optimizing herbicide use and improving weed management in field crops. The objective of this research was to evaluate the efficacy of commercial herbicide products and their selectivity in durum wheat by measuring the Normalized Difference Vegetation Index (NDVI). Field trials were conducted in Velestino and Kozani, Greece (2020–2021 and 2021–2022) in four site-years with the following treatment list: untreated control (T1), 2,4-D at 300 and 600 g a.e. ha−1 (T2 and T3, respectively), pyroxsulam + florasulam at 18.82 + 3.71 g a.i. ha−1 + cloquintocet-mexyl at 18.82 g a.i. ha−1 (T4), and mesosulfuron-methyl + iodosulfuron-methyl-sodium at 15 + 3 g a.i. ha−1 + mefenpyr-diethyl at 45 g a.i. ha−1 (T5). Site-years and treatments affected weed NDVI, weed biomass, crop NDVI, and grain yield (p ≤ 0.05). At Kozani, weed NDVI was lowest in T4 plots in 2020–2021 (0.31) and 2021–2022 (0.33). Treatments T4 and T5 resulted in lowest weed biomass in 2020-2021 (14–16 g m−2) and 2020-2021 (19–22 g m−2). At Velestino, T3 reduced weed biomass by 92 and 87% when compared to T5 in 2020–2021 and 2021–2022, respectively. Approximately, 67% and 73% of the variability in weed biomass in 2020–2021 and 2021–2022, respectively, at Kozani could be explained by weed NDVI. These parameters were strongly correlated in Velestino (R2 ≥ 90%). Low crop NDVI at Kozani indicated herbicide injury in T3 plots, confirmed by yield losses. During 2020-2021, yield was 30, 38, and 40% higher in T4 plots than in T2, T1, and T3 plots, respectively. At Velestino, yield in T1 plots was 25, 27, 27, and 29% lower than in T2, T4, T5, and T3 plots, respectively, in 2020–2021. Similar results were obtained in 2021–2022. The current study indicates that NDVI can be used as a reliable, non-subjective indicator of herbicide efficacy and selectivity in winter cereals. The methodology used in this work should also be evaluated in other crops and under different soil and climatic conditions.

The increased demand for the adoption of sustainable practices to protect agroecosystems is challenged by the introduction and dominance of invasive plant species (IPS). The management of IPS requires a direct response from farmers and policy makers and is often associated with the adoption of practices that have negative ecological impacts. Solanum elaeagnifolium Cav. (silverleaf nightshade) is a noxious IPS posing a serious threat to agriculture and the environment. The increased resistance to the biotic and abiotic stress factors caused by high phenotypic plasticity, dense trichomes, and spines allow the weed to adapt to many habitats, rendering several herbicides ineffective. If an early detection and eradication fails, multiple management strategies should be adopted to mitigate a further dispersal. Herbicides should be applied before or during flowering to prevent the formation of berries and the production of seeds. Precision agriculture tools, such as decision support systems, can be exploited to reduce the herbicide input. Soil tillage should be avoided to prevent clonal reproduction. Mowing is an effective tool to prevent the setting of seeds. Biological agents should be carefully released as a part of an agroecological weed management framework. Future research should focus on the development of cross-boundary protocols and actions to monitor the introduction pathways for the early detection and agroecological management of S. elaeagnifolium.

Intercropping cereals with legumes is a widely used agronomic practice to improve forage yield and quality in forage cropping systems. The main objective of the present study was to investigate the potential of a false seedbed to reduce weed pressure in intercrops and monocultures of annual ryegrass and berseem clover during the 2020–2021 and 2021–2022 growing seasons in western Greece. A split-plot randomized complete block design with four replications was set up. Seedbed manipulations assigned to the main plots included: normal seedbed preparation (NSB) and seeding, and two different false seedbeds. In the first (FSB 1) and second false seedbeds (FSB 2), weeds were controlled by shallow tillage at 1 and 2 weeks, respectively, after the first tillage and immediately before crop sowing. Forages were subplots of berseem clover (BCM) and annual ryegrass monocultures (ARM) and three intercrops with BCM:ARM ratios of 75:25 (ARBC 1), 50:50 (ARBC 2), and 25:75 (ARBC 3). FSB 1 reduced weed biomass by 27% and 34% compared to NSB in 2020–2021 and 2021–2022, respectively (p ≤ 0.001). FSB 2 improved forage yield by 9% and 14% in 2020–2021 and 2021–2022, respectively, compared to FSB 1. Compared to NSB, FSB 2 also increased forage yield by 11% in 2020–2021 and 17% in 2021–2022. Berseem clover biomass was higher in FSB 2 than in NSB main plots in both years. In the first harvest, ARBC 3 was the most weed-suppressive intercrop, which also provided the highest forage yield in both the first and second harvests of both years, followed by ARM and ARBC 2. In the second harvest, forage yield was 11% and 12% higher in ARBC 3 subplots than in ARBC 1 and BCM subplots, respectively. Similar results were obtained for cumulative forage yield from two harvests. Further research is needed to evaluate other alternative practices for agroecological weed management in low-input forage production systems in the Mediterranean region.

Biostimulants are products that can increase crop growth and can be applied either to the soil or to the plant and seed of a wide range of crops. However, there is a large gap in knowledge regarding the potential interactions of biostimulants with plant protection products like herbicides. The present review aims to highlight various effects of the combined use of biostimulants with herbicides in terms of weed management, crop yield and quality parameters. Special emphasis is given to the comparison between the combined use of biostimulants with herbicides and herbicides used alone (without biostimulants). In wheat and potato, the combined use of biostimulants with herbicides can in some cases be beneficial for the crop compared with herbicides alone, with recorded yield increases of up to 14.7% depending on the biostimulant, the herbicide, the year and the method of application (mixture or sequentially). Combining herbicides and biostimulants shows potential to achieve good weed management while improving crop yields and quality and thus lower herbicide rates could be probably used for sufficient weed control in full agreement with the goals of Green Deal and agroecology approaches.

Sulla (Hedysarum coronarium L.) is a new candidate crop for biofuel production. A field trial was conducted in 2018–2020 in Pyrgos, Greece, and repeated in 2019–2021 to evaluate different row spacings and cover crops for weed management in sulla in a two-factor randomized complete block design (RCBD) with four replications. Four row spacings, namely 76-cm, 51-cm, 38-cm, and 19-cm, were assigned to the main plots. Three cover crops, namely farro wheat (Triticum turgidum subsp. dicoccum (Schrank ex Schübler) Thell.), common vetch (Vicia sativa L.), white mustard (Sinapis alba L.), and an untreated control, were assigned to the subplots. In the first year of sulla growth, weed biomass, sulla stem, and total dry matter yield (DMY) were affected by growing cycles (p-value ≤ 0.05). The 19- and 38-cm row spacings resulted in the lowest weed biomass and the highest stem and total sulla DMY in the first year of sulla growth. White mustard was the most weed-suppressive cover crop in both years and growing cycles followed by farro heat. The highest stem DMY was observed in subplots with white mustard in both years. The combination of 38 cm row spacing and white mustard as a cover crop resulted in the highest cumulative two-year sulla DMY (18.9 t ha−1). Further case studies are needed to evaluate more cultural practices for weed management in sulla and other major biomass crops under different soil and climatic conditions.

Bioherbicides are naturally originated products posing alternatives to synthetic herbicides for weed control. The objective of this study was to evaluate the efficacy of pelargonic acid and microencapsulated caraway essential oil on barnyardgrass (Echinochloa crus-galli (L.) P.Beauv.) and johnsongrass (Sorghum halepense (L.) Pers.). Two separate pot experiments were conducted at the Agricultural University of Athens (spring 2021), arranged in a completely randomized design (CRD) with six weed control treatments replicated four times. Treatments included the applications of: microencapsulated caraway essential oil at 50 g L−1 (CAR), CAR plus a commercial adjuvant (CAR + adj), i.e., alcohol ethoxylate at 1.8 g L−1, pelargonic acid at 36.3 g L−1 (PA), PA plus a commercial adjuvant (PA + adj), i.e., alcohol ethoxylate at 1.8 g L−1, and a tank mixture of pelargonic acid at 64 g L−1 plus microencapsulated caraway essential oil at 50 g L−1 (PA + CAR). An untreated control (CON) was also included. The results of the current research confirmed the knock-down effect of pelargonic acid against both barnyardgrass and johnsongrass and demonstrated the low efficacy of caraway microcapsules. The addition of a commercial adjuvant improved the efficacy of caraway essential oil but did not appear to affect the performance of pelargonic acid. No synergistic effects were observed between pelargonic acid and microencapsulated caraway essential oil. Further research is needed to optimize the use of these and other natural herbicides for weed control in agriculture and as components of sustainable integrated weed management (IWM) systems.

Improving ecological connectivity (EC) within landscapes by establishing corridors and ecological networks has been proposed to counteract the negative effects of habitat fragmentation and climate change on biodiversity. To be functional, ecological networks should be kept free of opportunistic invasive species that can disrupt EC between protected areas and cause biodiversity loss. The present study focused on perennial herbaceous species whose occurrence in the Adriatic-Ionian region has increased in the last two decades, namely common milkweed (Asclepias syriaca), Jerusalem artichoke (Helianthus tuberosus), Japanese knotweed (Reynoutria japonica), Bohemian knotweed (Reynoutria × bohemica), giant hogweed (Heracleum mantegazzianum), giant goldenrod (Solidago gigantea), Canadian goldenrod (Solidago canadensis), and Bermuda buttercup (Oxalis pes-caprae). All species have a high potential to spread in grasslands, abandoned agricultural fields, forest edges, and riparian areas and pose a significant threat to native plant communities and biodiversity. Restoring heavily infested sites is a major challenge because these perennial invaders are very persistent and tend to alter the soil environment in invaded habitats and prevent the recolonization of native plant communities. Therefore, early action should be taken to prevent the spread of these environmental weeds in ecological networks and protected areas with high conservation value.

In the field of Agricultural University of Athens, the effects of false seedbed technique, stale seedbed, chemical and ecologically based control on weed growth and soybean yield were evaluated (2019). The experimental treatments were: normal seedbed, normal seedbed along with pre-emergence chemical control, false seedbed, stale seedbed with glyphosate and stale seedbed with pelargonic acid. In the plots of normal seedbed along with pre-emergence chemical control, pendimethalin was applied at rate of 1560 g a.i. ha-1. In the plots of stale seedbed with glyphosate, glyphosate was applied at a rate of 2160 g a.e. ha-1 and in the plots of stale seedbed with pelargonic acid, pelargonic acid was applied at a rate of 31020 g a.i. ha-1. The experiment was conducted in a randomized complete block design with three replicates. The results revealed that stale seedbed combined either with glyphosate or pelargonic acid application reduced annual weeds’ density by 94 and 95% as compared to normal seedbed. Stale seedbed along with pelargonic acid reduced the density of perennial weeds by 36, 38 and 41% as compared to the combination of normal seedbed and pre-emergence chemical control, normal seedbed and false seedbed, respectively. The application of glyphosate in stale seedbed plots was also effective against perennial weeds. It was also observed that stale seedbed along with glyphosate increased soybean seed yield by 17, 19 and 35% as compared to the combination of normal seedbed and pendimethalin application, false seedbed and normal seedbed, respectively. Beneficial were also the effects of the combination of stale seedbed and pelargonic acid not only on soybean seed yield but also on soybean protein content. Further research is needed in order to investigate the role of false and stale seedbeds as integrated weed management practices in various crops and under different soil and climatic conditions. Research is also needed to evaluate pelargonic acid for weed control in stale seedbeds since it is an eco-friendly herbicide with no restrictions for organic farming.

Agricultural systems in the EU have become more vulnerable and less sustainable due to an overreliance on herbicides and the tremendous increase in herbicide-resistant weeds. The EU Green Deal aims to reduce the use and risk of chemical pesticides by 50% by 2030, although it is still undefined whether a reduction in herbicide use could be feasible in different farming systems and situations. This review aims to provide a holistic framework for sustainable crop and weed management to reduce the herbicide input and ensure crop protection. Current and future dilemmas and policies that need to be handled to ensure the agroecological transition of the EU’s agricultural systems are also discussed. The integration of non-chemical alternatives for integrated weed management is feasible and includes novel cultivation techniques (e.g., intercropping, false seedbed, reduced tillage, crop rotation and diversification, adjustments on sowing densities and dates), non-chemical tools (e.g., flaming, seed coating, beneficial microorganisms, mechanical weeding, biocontrol agents and natural herbicides), competitive plant material (hybrids and cultivars, cover crops, service crops), and new technologies and precision agriculture tools (e.g., Decision Support Systems, robots, remote sensing, UAVs, omics and nanotechnology). A special focus should be appointed to agroecology and biodiversity conservation.

Low-diversity weed communities are dominated by few species that are highly competitive to crops. The management of such weed communities should rely upon sustainable cultural and non-chemical practices, especially in crops such as spinach (Spinacia oleracea L.), where very few herbicides are available. A two-year field trial (2020 and 2021) was conducted to evaluate different fertilization practices (broadcast and banded), intra-row spacings (15 cm, 11 cm, 7 cm), and mechanical weed control treatments (untreated, one treatment, two treatments) for the management of a low-diversity weed community in spinach. Weed competition severely affected spinach commercial biomass (R2 = 0.845). Compared to broadcast fertilization, banded fertilization reduced weed biomass and improved spinach yield and nitrogen use efficiency. Narrow intra-row spacing (7-cm) reduced weed biomass by 28 and 45% compared to intra-row spacings of 11-cm and 15-cm, respectively. Two mechanical weed control treatments resulted in 49% lower weed biomass compared to a single treatment. Commercial biomass increased with decreasing intra-row spacing (R2 = 0.881) and increasing the number of mechanical treatments (R2 = 0.911). More cultural and non-chemical practices should be evaluated for weed management in spinach, especially at sites infested with low-diversity weed communities.

Shattercane (Sorghum bicolor (L.) Moench subsp. drummondii) and weedy sunflower (Helianthus annuus L.) are two examples of crop wild relatives (CWRs) that have become troublesome weeds in agriculture. Shattercane is a race belonging to a different subspecies than domesticated sorghum (Sorghum bicolor (L.) Moench subsp. bicolor). Weedy sunflower populations are natural hybrids between wild and domesticated sunflower (Helianthus annuus L.). Both species have key weedy characteristics, such as early seed shattering and seed dormancy, which play an important role in their success as agricultural weeds. They are widely reported as important agricultural weeds in the United States and have invaded various agricultural areas in Europe. Shattercane is very competitive to sorghum, maize (Zea mays L.), and soybean (Glycine max (L.) Merr.). Weedy sunflower causes severe yield losses in sunflower, maize, soybean, pulse crops, and industrial crops. Herbicide resistance was confirmed in populations of both species. The simultaneous presence of crops and their wild relatives in the field leads to crop–wild gene flow. Hybrids are fertile and competitive. Hybridization between herbicide-tolerant crops and wild populations creates herbicide-resistant hybrid populations. Crop rotation, false seedbed, cover crops, and competitive crop genotypes can suppress shattercane and weedy sunflower. Preventative measures are essential to avoid their spread on new agricultural lands. The development of effective weed management strategies is also essential to prevent hybridization between sorghum, sunflower, and their wild relatives and to mitigate its consequences.

Amaranthus palmeri S. Wats., or commonly Palmer amaranth, is an invasive plant species that has invaded many countries worldwide and causes significant yield losses to annual spring crops. Palmer amaranth biotypes were detected in maize and sorghum fields in Western Greece and cotton fields in Central Greece in 2020. The infestations were recorded both inside the crops and in the margins of the fields, indicating that Palmer amaranth could be characterized as an invasive weed for these regions and, thus, must be urgently managed. Four biotypes were screened for resistance to 2,4-D and nicosulfuron by using NDVI, canopy cover, photochemical efficiency, plant height and fresh weight values. All biotypes showed resistance to nicosulfuron. Resistance cases to important herbicides (i.e., ALS and synthetic auxins) in spring crops, such as maize and cotton, indicate that management could become even more challenging if farmers do not adopt integrated strategies and tools to manage this weed. The eradication of Palmer amaranth plants is imperative, since it has yet to be dispersed in several agricultural areas of Greece. Palmer amaranth is recommended to be enlisted as quarantine pest for regulation in Greece.

Lignocellulosic biomass is one of the dominant renewable energy resources suited for the production of sustainable biofuels and other energy purposes. This study was focused on weed management strategies that can improve the establishment of six lignocellulosic crops. The studied crops included: giant miscanthus, switchgrass, giant reed, cardoon, sweet sorghum, and kenaf. Delayed planting, increased planting densities, and mulching techniques can suppress weeds in giant miscanthus. Weed competition is detrimental for switchgrass establishment. Seedbed preparation and cultivar selection can determine its ability to compete with weeds. Giant reed is unlikely to get outcompeted by weeds, and any weed control operation is required only for the first growing season. Competitive cultivars and increased seeding rates maximize the competitiveness of cardoon against weeds. Several cultural practices can be used for non-chemical weed management in sweet sorghum and kenaf. For all crops, pre-emergence herbicides can be applied. The available safe post-emergence herbicides are limited. Mechanical weed control during crucial growth stages can provide solutions for sweet sorghum, kenaf, and perennial grasses. Further research is required to develop effective weed management strategies, with emphasis on cultural practices, that can improve the establishment of these prominent lignocellulosic crops.

Irrigation is an agronomic practice of major importance in alfalfa (Medicago sativa L), especially in the semiarid environments of Southern Europe. Field experimentation was conducted in Western Greece (2016–2018) to evaluate the effects of irrigation timing on weed presence, alfalfa yield performance, and forage quality. In a randomized complete block design (four replications), two cultivars (“Ypati 84” and “Hyliki”) were the main plots, while three irrigation timings were the subplots (split-plot). The irrigation timings were IT-1, IT-2, and IT-3, denoting irrigation 1 week before harvest, 1 week after harvest, and 2 weeks after harvest, respectively. IT-1 reduced Solanum nigrum L. density by 54% and 79% as compared to IT-3 and IT-2, respectively. Chenopodium album L. density was the highest under IT-2. IT-3 resulted in 41% lower Amaranthus retroflexus L. density in comparison to IT-2, while the lowest values were observed under IT-1. Stand density and stems·plant−1 varied between years (p ≤ 0.05). Mass·stem−1 and alfalfa forage yield were affected by the irrigation timings (p ≤ 0.001). Total weed density and forage yield were negatively correlated in both the second (R2 = 87.013%) and the fourth (R2 = 82.691%) harvests. IT-1 and IT-3 increased forage yield, leaf per stem ratio, and crude protein as compared to IT-2. Further research is required to utilize the use of cultural practices for weed management in perennial forages under different soil and climatic conditions.

In this work, we studied the effect of three glyphosate formulations (isopropylamine, ammonium and potassium salts) and two non-ionic adjuvants on the resistance response of two resistant (R1, R2) and one susceptible population of the highly invasive Asteraceae, Conyza sumatrensis, from Southern France vineyards. Only in R1, an amino acid substitution (Pro106Thr) was found in the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). The two adjuvants, in a similar fashion, significantly reduced GR50 values for every population and glyphosate formulation. Without adjuvants, glyphosate as potassium salt was the only formulation able to significantly reduce the GR50 values of every population. For every population, the two adjuvants improved, indistinguishably, leaf retention of the herbicidal solution and the potassium salt formulation led to the highest retention, both with and without the adjuvant added. Uptake responses paralleled those of retention and adjuvant addition was more effective in increasing foliar uptake of the lower performing formulations (isopropylamine and ammonium salts). The allocation pattern of glyphosate among plant compartments was only dependent on population, with R2 retaining most glyphosate in the treated leaf, clearly suggesting the occurrence of a Non-Target Site Resistance (NTSR) mechanism. Results indicate that control of weed populations possessing NTSR mechanisms of resistance to glyphosate may be improved through adequate selection of formulation and adjuvant use.

There is growing consideration among farmers and researchers regarding the development of natural herbicides providing sufficient levels of weed control. The aim of the present study was to compare the efficacy of four different pelargonic acid products, three essential oils and two natural products’ mixtures against L. rigidum Gaud., A. sterilis L. and G. aparine L. Regarding grass weeds, it was noticed at 7 days after treatment that PA3 treatment (pelargonic acid 3.102% w/v + maleic hydrazide 0.459% w/v) was the least efficient treatment against L. rigidum and A. sterilis. The mixture of lemongrass oil and pelargonic acid resulted in 77% lower dry weight for L. rigidum in comparison to the control. Biomass reduction reached the level of 90% as compared to the control in the case of manuka oil and the efficacy of manuka oil and pelargonic acid mixture was similar. For sterile oat, weed biomass was recorded between 31% and 33% of the control for lemongrass oil, pine oil, PA1 (pelargonic acid 18.67% + maleic hydrazide 3%) and PA4 (pelargonic acid 18.67%) treatments. In addition, the mixture of manuka oil and pelargonic acid reduced weed biomass by 96% as compared to the control. Regarding the broadleaf species G. aparine, PA4 and PA1 treatments provided a 96–97% dry weight reduction compared to the corresponding value recorded for the untreated plants. PA2 (pelargonic acid 50% w/v) treatment and the mixture of manuka oil and pelargonic acid completely eliminated cleaver plants. The observations made for weed dry weight on the species level were similar to those made regarding plant height values recorded for each species. Further research is needed to study more natural substances and optimize the use of natural herbicides as well as natural herbicides’ mixtures in weed management strategies under different soil and climatic conditions.

E. colona is a C4 annual summer grass which is troublesome to major summer annual and perennial crops. Due to recent complaints by the farmers, the objectives of the present study were to evaluate the efficacy of penoxsulam, profoxydim, cycloxydim, cyhalofop-butyl, florpyrauxifen-benzyl and glyphosate against six E. colona accessions, and also to evaluate the response of these accessions to different rates of glyphosate in a dose-response experiment. In the first experiment, herbicides were applied at their maximum recommended label rates, while in the dose-response experiment, glyphosate was applied at six doses corresponding to 0, 1/4X, 1/2X, X, 2X, and 4X of the recommended rate. The dry weight of the biotypes TH8 and TH7 treated with profoxydim was 66% and 68% of the untreated control, respectively. The efficacy of cyhalofop-butyl against three accessions was lower than 30%, while two accessions were susceptible to this herbicide. The efficacy of penoxsulam against the biotypes ET2 and ET4 was lower than 10%, while dry weight of FT5 and TH8 was only reduced by 23%–28% as compared to the control. Cycloxydim application provided control higher than 75% at 21 days after treatment (DAT) of three accessions, while the majority of E. colona accessions was adequately controlled by the application of florpyrauxifen-benzyl. The response of the different accessions to glyphosate varied. The results of the glyphosate dose-response experiment revealed that the GR50 values of the resistant E. colona accessions ET2 and ET4 were up to 1098 and 1220 g a.e. ha−1 of glyphosate, respectively, whereas the GR50 value of the susceptible accession (FT5) was only 98 g a.e. ha−1. The resistance indices of ET2 and ET4 were 12.4 and 11.2, respectively, indicating that they have already developed resistance to glyphosate. Three more accessions could be also of developing resistant to glyphosate. This is the first report of glyphosate resistance from E. colona accessions in Greece, with indications of multiple resistance also present. Further research is needed in order to evaluate the efficacy of several herbicides under different soil and climatic conditions, conduct baseline sensitivity studies, reveal the evolvement of resistance patterns to glyphosate from accessions of Echinochloa spp., and search for alternative options of weed management in annual and perennial crops due to the clear indications of multiple resistance situations.

Decision support systems (DSS) have the potential to support farmers to make the right decisions in weed management. DSSs can select the appropriate herbicides for a given field and suggest the minimum dose rates for an herbicide application that can result in optimum weed control. Given that the adoption of DSSs may lead to decreased herbicide inputs in crop production, their potential for creating eco-friendly and profitable weed management strategies is obvious and desirable for the re-designing of farming systems on a more sustainable basis. Nevertheless, it is difficult to stimulate farmers to use DSSs as it has been noticed that farmers have different expectations of decision-making tools depending on their farming styles and usual practices. The function of DSSs requires accurate assessments of weeds within a field as input data; however, capturing the data can be problematic. The development of future DSSs should target to enhance weed management tactics which are less reliant on herbicides. DSSs should also provide information regarding weed seedbank dynamics in the soil in order to suggest management options not only within a single period but also in a rotational view. More aspects ought to be taken into account and further research is needed in order to optimize the practical use of DSSs for supporting farmers regarding weed management issues in various crops and under various soil and climatic conditions.

Glyphosate retention, absorption and translocation with and without adjuvant were examined in Lolium rigidum and Conyza canadensis in greenhouse and laboratory settings to develop an understanding of the influence of the selected adjuvant on glyphosate activity. Tests on whole plants show that the dose of herbicide needed to reduce dry weight by 50% (GR50) or plant survival (LD50) decreases by mixing glyphosate and adjuvant to 22%−24% and 42%−44% for both populations of L. rigidum and C. canadensis, respectively. This improvement in efficacy could be attributed to the higher herbicide retention and lower contact angle of the glyphosate + adjuvant drops on the leaf surface compared to the glyphosate solution alone. Plants of both species treated with 14C-glyphosate + adjuvant absorbed more glyphosate compared to non-adjuvant addition. Furthermore, the movement of the herbicide through the plant was faster and greater with the adjuvant. Our results reveal that the use of adjuvants improves the effectiveness of glyphosate in two of the most important weeds in agricultural crops in Mediterranean countries.

Herbicide deposition rate can be affected by the leaf surface features of weeds and have a significant impact on the overall efficacy. In this paper, an orthogonal experiment was conducted to investigate the differences of droplet evaporation and spreading characteristics corresponding to weed leaf surface with hairy, waxy and rough (ridged) structures. Three weed species—Descurainia sophia, Lepidium lotifolium, and Lolium temulentum—were included in the study, representing these three leaf structures respectively. Glyphosate sprays with organic silicone surfactant in different concentrations were composed for the test. Single droplets with two diameters of 0.05 μL and 0.1 μL were deposited on the leaves to evaluate the evaporation and spreading characteristics. A digital camera was used and the evaporation duration and the maximum droplet coverage images could be captured and extracted from the recorded videos. The Image Processing Toolbox in Matlab was applied to segment the images for droplet and leaf background and the binary images’ pixel numbers were counted for coverage area calculation. The results revealed that the evaporation duration was reduced with the increase of the organic silicone concentration, while the spread area was expanded. The droplet spread more widely and evaporated faster on D. sophia leaves than on the leaves with L. lotifolium and L. temulentum surfaces. The spreading area and evaporation duration varied much faster on L. lotifolium leaves than on the leaves of other weed species. The droplet sizes affected spreading more significantly on L. temulentum leaf surface, as the spreading procedure of small size droplets was restrained by the groove structure. The results of this study would benefit the consideration of the farmers when selecting the proper nozzle code and the determining of the surfactant mixture in order to optimize the use of herbicides like glyphosate.