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The herbicide glyphosate (N-phosphonomethylglycine) has been the most commonly applied herbicide worldwide for the past 40 years. This review presents and discusses the state of knowledge concerning groundwater contamination by glyphosate and its metabolite, aminomethylphosphonic acid (AMPA). A dataset of 48 reports and articles reporting on glyphosate and AMPA in groundwater worldwide was constructed from the published literature. Specific attention was given to the analysis of available studies on glyphosate and AMPA transport in groundwater to investigate groundwater contamination factors. The information presented in this review highlights detectable groundwater contamination in several countries, with many cases exceeding European groundwater quality standards. Both agricultural and non-agricultural applications of glyphosate can be significant sources of pollution, and proximity to agricultural fields is a significant risk factor. AMPA has two primary sources, glyphosate and amino polyphosphates, but very little information is available about the origin of AMPA detected in groundwater. Glyphosate and AMPA transport to groundwater can be significant in well-structured soils that are rich in macropores, where it generally occurs via preferential flow. An inverse relationship was highlighted between the groundwater depth and glyphosate and the occurrence and concentration of AMPA in groundwater; however, some discrepancies among the studies were identified. Heavy rainfall shortly after glyphosate application poses a high risk of its transport to groundwater. Seasonal trends in glyphosate and AMPA in groundwater, related to application timing, agronomic practices, and weather conditions, were also observed. Finally, risk-management measures are proposed.

Abstract This study investigates the adsorption and dissipation of glyphosate and the formation/dissipation of AMPA in non-tilled (NT) and conventionally tilled (CT) soil at 0–5 and 5–20 cm depth. Glyphosate adsorption was mainly related to the different NT and CT soil properties (clay and amorphous Al oxides), whereas an effect of the soil management could not be identified. Glyphosate dissipation was initially fast, and it slowed down later. The initial glyphosate concentration in NT soil at 0–5 cm was significantly lower than the dose applied due to the interception by the weeds and crop residues. AMPA began to form early after treatment and persisted longer than glyphosate. The DT50 range was 8–18 days for glyphosate and 99–250 days for AMPA. Longer glyphosate and AMPA DT50 were observed in NT soil compared to CT soil but, for glyphosate, the difference was significant only at 5–20 cm. Higher glyphosate and AMPA concentrations were detected in NT than in CT soil at the end of the study at 0–5 cm. The differences in glyphosate and AMPA DT50 and persistence were mainly attributable to the influence of different NT and CT soil characteristics. However, other factors could have contributed to the different glyphosate and AMPA dynamics between the soils, like glyphosate wash-off from crop residues on NT soil with the rainfall, the delayed glyphosate return to the soil by weed root exudation or weeds decomposition, and the NT soil compaction which may have reduced the microbial degradation of glyphosate at low concentrations. Graphic abstract

Modern viticulture cannot be practiced without the use of plant protection products to control diseases like downy mildew, powdery mildew, and pests. In severely sloping vineyards, where mechanization is not possible, pesticide application is realized using spray guns, which is a laborious, expensive, and dangerous application technique. In these vineyards, where viticulture is defined as “heroic viticulture,” vine-growers could seriously take advantage of innovation in spray-technique applications. For this reason, several prototypes of a fixed spraying system (FSS) were realized in recent years. Two prototypes of a fixed spraying system were built in 2019 in two different vineyards in the Veneto region (north-eastern Italy). In both vineyards, the fixed spraying systems were used to perform pesticide application during the 2020 season to control downy mildew, powdery mildew, and pests. With this solution, both vineyards were successfully protected, resulting in comparable infection degrees and yields as the ones protected with airblast sprayers and spray guns. This study contributes to assert fixed spraying systems as an innovation that could improve working conditions, safety, timing, and performances of plant protection products’ application in heroic viticulture areas.

Glyphosate (GLP) has been the most frequently used herbicide worldwide, including Europe. Due to its systemic, post-emergence, and non-selective characteristics, it offers optimal weed control without the need of mechanical treatments. Therefore, it is widely used in no-till practices. However, increasing awareness of its potential harmful effect to human health and ecosystems has led numerous countries to restrict or, even, ban its use. The EPIC (Environmental Policy Integrated Climate mode) model has been selected as a screening tool to evaluate the vulnerability of groundwater to glyphosate contamination under different pedo-climatic and agronomic conditions across the Veneto Region (NE Italy), an area where the interaction of different pedo-climatic and agronomic conditions makes it difficult to predict site-specific GLP movement. The aim of this study was to evaluate the performance of a modified version of EPIC that includes a fast solution of Richards’ equation to predict GLP dynamics under shallow water table conditions. The experimental site was in Northeastern Italy and consisted of eight drainable lysimeters; 4 treatments, replicated twice, in factorial combination of two management practices (conventional -CV- and conservation -CA- agriculture) and two water table levels (60 and 120 cm). Degradation and movement of GLP in the soil profile were monitored in 2019 from May to September. The herbicide (144 mg m-2) was applied on bare soil in CV and on the cover crop (Secale cereale) in CA. Water samples were systematically collected at 15, 30 and 60 cm depth using suction cups, whose suction was regulated by an automated system that combined matric potential readings, provided by electronic tensiometers, with a vacuum regulator. Water samplings from groundwater were also performed. Soil samples were collected at 0-5 and 5-15 cm depth every other week. Weather and soil data were used as input to EPIC, while the GLP experimental results, along with yields, soil water content, evapotranspiration and water percolation data, were used to calibrate (from 2011 to 2017) and validate (from 2018 to 2019) the model. In all lysimeters, GLP reached the groundwater the day after the first irrigation event, with higher leaching in CV than in CA and at 120 than at 60 cm. After 40 days, GLP was almost completely dissipated in CA soil, while it was still detected in CV. EPIC was able to acceptably reproduce evapotranspiration (R2=0.76), yields (R2=0.74) and water percolation (R2= 0.59-0.90). In general, GLP predictions compared well with observations but the predictions in CV treatments were closer to observations than in CA treatments. This work showed the robustness of the modified EPIC, suggesting its use as a tool to assess the potential vulnerability of the groundwater under different management scenarios and water table levels.

Broad contamination of systemic herbicide glyphosate –GLP– (N-(phosphonomethyl) glycine) and its metabolite aminomethylphosphonic acid (AMPA) in soil and water has become one of the main environmental issues worldwide, raising awareness of the potential harmful effects to human health and ecosystems. Physical, chemical, and biological soil properties contribute to the complex interaction between GLP and the environment, that makes any prediction of adsorption, transport, and degradation dynamics still challenging.Within a wide project –SWAT– that tries to link GLP and AMPA dynamics through the vadose zone with groundwater contamination, the specific goals of this work are: 1. monitoring soil and water contamination of GLP and AMPA in agricultural lands; 2. identifying the driving factors leading to site-specific soil-water contaminant interactions.Two experimental sites were located in northeastern Italy (Conegliano and Valdobbiadene municipalities) in the winegrowing terroir of the Prosecco wine production, recently included in the UNESCO’s World Heritage List. Each site was equipped with two soil-water monitoring stations (25 m2 each), multi-sensor soil probes (temperature and water content) and suction lysimeters to monitor the full soil profile. Undisturbed soil cores were also collected and later analyzed for hydraulic, physical and chemical properties down to 70 cm. After GLP field contamination on November 2018 (0.188 g m-2), soil and water were systematically sampled from each site, starting immediately after contamination and thereafter at each rain event for 6 months. Adsorption coefficients (Kf) were estimated in laboratory in order to get information about GLP sorption to soil particles at different soil layers along the full soil profile. Site-specific dissipation kinetics (DT50) were also evaluated to better understand its decay rate.First results revealed that GLP transport was highly site specific and locally affected by preferential flows when intense rainfall events occurred (12 mm h-1 max rainfall intensity): GLP showed strong binding affinity to soil particles in the topsoil layer and it likely bypassed the porous matrix towards the deepest layers, where it was detected as in the surface one. The GLP dissipation dynamic was completed after 6 months of experimentation, whereas AMPA was still detected in the topsoil layer, attesting the full degradation after almost 300 days. Site-specific laboratory and field data will be integrated and further discussed to better understand the fate of glyphosate and AMPA in the vadose zone.

Glyphosate is the most used herbicide worldwide, especially in conservation agriculture, where the lack of mechanical weed control often necessitates chemical inputs. In conservation agriculture, the elimination of tillage operations leads to changes in soil physical, chemical, and biological properties. Consequently, herbicide environmental fate may be potentially altered relatively to conventional tillage systems. The aim of this study was, therefore, to investigate the effect of conservation agriculture and conventional tillage on the adsorption of glyphosate and on the dissipation of glyphosate and its primary metabolite aminomethylphosphonic acid (AMPA) at two depths, 0−5 and 5−20 cm.The field trial was conducted from October 2018 to April 2019 at the Padua University Experimental Farm, North-East Italy. Glyphosate was applied as a formulated product (Roundup Power 2.0) at a dose of 1.44 kg/ha of the active ingredient. The dissipation of glyphosate and the formation/dissipation of AMPA were followed for 182 days after their application. The concentrations of glyphosate and AMPA in the soil were analysed by Ultra-High Performance Liquid Chromatography coupled with mass spectrometry. The dissipation of glyphosate was described by the first-order multicompartment model (FOMC), whereas the model for AMPA was composed of an FOMC degradation model for glyphosate and the single first-order degradation model for AMPA. The estimated trend of concentrations over time for both glyphosate and AMPA were used to derive their DT50 (time required for 50% dissipation of the initial concentration).The results indicate an increase in glyphosate adsorption in non-tilled soil compared to the tilled soil, at both depths. Glyphosate initial dissipation was fast, followed by a slower decline. At 0–5 cm no significant difference was observed in glyphosate persistence between the two soil managements, whereas at 5–20 cm glyphosate was more persistent in non-tilled soil (DT50 18 days) than in tilled soil (DT50 8 days). The fast initial dissipation of glyphosate was reflected in an increase in the concentration of AMPA. AMPA persisted longer than glyphosate but, for this metabolite, no apparent effect was observed in response to the different soil management. The higher persistence of glyphosate under conservation tillage might increase the risk of on-site soil pollution due to the accumulation of this chemical, especially in the case of repeated applications of glyphosate. Nevertheless, high glyphosate adsorption observed in non-tilled soil may reduce the leaching potential to lower soil depths.This abstract falls in the group “Soil contamination” and the subgroup “Experimental assessment”.

Field management practices can alter the physical and chemical properties of the soil, also causing changes to the seed bank. Alterations can also occur to the soil microbial community, which in turn can increase or diminish the process of weed seed decay. In this research, the issue of seed degradation was studied in an undisturbed and a no-till soil, trying not only to uncover where seeds are more degraded, but also to investigate the microbial activities that could be involved in this process. Six different weed species, commonly found in northern Italy, were used: Abutilon theopharsti, Alopecurus myosuroides, Amaranthus retroflexus, Digitaria sanguinalis, Portulaca oleracea and Sorghum halepense. Seed decay was tested in two different sites, a no-till field and the adjacent buffer zone. Soil microbial activity was also measured using the Fertimetro, an approach based on the degradation of cotton and silk threads buried in the soil for one week. Degradation of the buried seeds was higher in the no-till field soil than in the buffer strip for all the studied species as was the microbial cellulolytic activity. Even though the buffer strip soil is an undisturbed habitat and resulted as having higher organic matter, the no-till soil conditions appeared more unfavourable to seed viability. Our findings suggest that no-till management can improve weed seed suppression in the soil. Moreover, cellulolytic microorganisms play an important role in seedbank longevity, so cellulolytic activity surveys could be used as an early monitoring bioindicator for weed seed suppression in soil.

Summary Modelling weed seedling emergence pattern appears to be a promising approach in the development of effective weed management programmes based on the selection of optimal timing of control operations. Thermal and hydrothermal time models propose that seed germination rates are proportional to the amount by which temperature and water potential exceed threshold values for these environmental factors. Hence, base temperature for seed germination is a fundamental biological parameter for the prediction of weed emergence. A series of laboratory experiments were conducted to estimate base temperature in three weed species belonging to the Asteraceae family, predominant in conservation tillage fields in north-eastern Italy. The traditional method based on germination assays at constant temperatures was compared with a method based on assays at alternating temperatures. The latter might represent an alternative to the former for those species which do not germinate or only poorly under constant temperatures. Base temperature was estimated by regressing the reciprocal of the median germination time on temperature comparing two functions, a broken-stick and an exponential-type model. Both models showed good fit to all data in the whole temperature range and in almost all cases provided similar estimates of base temperature. The main result is that, for the weed species examined in this study, the use of alternating temperatures for base temperature estimation appears to be possible. However, further research is required to test if the use of germination assays performed at alternating temperatures can be a suitable method to estimate base temperature of species that have too low germination at constant temperatures.

The role played by organic farming as an alternative system to conventional farming is widely questioned, since conflicting results on crop yields sometimes greatly affect system efficiency. As a result, prolonged monitoring studies on organic (OF) and conventional farming (CF) systems are still required, especially in real-life farm conditions, in which the entire production process is quantified. In this context, this study reports crop yields (winter wheat, maize, soybean) and energy efficiency, over a 13-year monitoring period, on a farm in north-east Italy in which two sectors are farmed following OF and CF practices. Results showed that organic yields were always lower than conventional ones, averaging 69%, although their range varied greatly over the years (from 45% to 90%) and depended on crop type. Several management constraints had effects on the lower yields, especially reduced available nutrients and cropping season, but also the timings and types of tillage operations. By contrast, OF practices usually had positive effects on the environment, due to reduced energy input mainly fertilisation (−33.4% MJ ha −1 y −1 ) and the generally higher productivity of invested energy (E Out E In −1 = 4.53 in OF and 4.28 in CF); energy use differences per product unit were mainly equal. Other factors, such as local climate and soil variability, may have influenced system performance, but as the two experimental sites were located at a distance of 3.5 km from each other, the data reported here are still valuable, in that they represent the results of 13 years of monitoring, during which farm management played a major role. This case study, although conducted in two separate sites, did not highlight the best overall solution at farm level, it does indicate that the agricultural systems applied would be better suited for different situations and targets (e.g., productive, energetic, ecologic).

Glyphosate-resistant biotypes of Eleusine indica (L.) Gaertn. have been detected in Asia, the Americas but not in Europe. The aim of this study was to evaluate resistance levels and possible target site resistance mechanisms of an E. indica biotype (19-1) collected from a plant nursery in Southern Italy where poor glyphosate efficacy was reported. Two dose-response experiments were conducted to evaluate the sensitivity of biotype 19-1 to glyphosate in comparison with two susceptible checks. 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) sequencing was performed to identify possible mutations conferring the resistance. The susceptible biotypes were completely controlled at the glyphosate recommended field dose of 360 g ae ha&minus, 1, while 50% of the plants of biotype 19-1 survived at 1440 g ae ha&minus, 1. The resistance index of biotype 19-1 ranged between 5.8 and 7.3 for the response variables of fresh weight reduction and plant survival, respectively. All the plants surviving glyphosate application and sampled for DNA analyses had the point mutation P106A. The biotype 19-1 can be confirmed as glyphosate-resistant, representing the first glyphosate-resistant population of E. indica in Europe.

The multidisciplinary research project SWAT - Subsurface Water quality and Agricultural pracTices monitoring - has been set up to assess pesticides contamination risks for groundwater in the hills of Prosecco in the north-east of Italy. The unconfined aquifer underneath the typical Glera grape-variety vineyards of Valdobbiadene and Conegliano is used as water supply resource for human consumption. The principal aim of the project SWAT is to obtain a thorough information on the impact of contaminants coming from agricultural practices and infiltrating in the soil of well protection areas. Based on specifically designed field experiments, a study on water and solutes infiltration process is developed to understand the movement and evolution of chemical species in the vadose zone. A one-dimensional transport model for unsaturated media (BRTSim - Maggi, 2015) is used to simulate solute infiltration and estimate the soil hydraulic parameters. Monitoring activities started in November 2018 in two experimental sites (the Settolo site in Valdobbiadene and the Colnù site in Conegliano) near supply wells surrounded by vineyards. A mixture of Bromide and Glyphosate was identically applied on two parcels of 25 m2 for each experimental site to obtain information about spatial heterogeneity and to collect independently water and soil quality measurements. Porous cups, for the collection of infiltrating water, and capacitive sensors, to gauge temperature and Volumetric Water Content (VWC), were installed beneath the sectors at three depths (-0.1, -0.3, -0.7 m). In each site meteorological station provides hydrological data. At first, laboratory analysis on soil samples collected at the same depths gave a vertical distribution of the sector-specific soil texture that was used as input for Rosetta to obtain initial estimations of retention curve behaviour and the saturated hydraulic conductivity. These data allowed us to develop an open-loop simulation using the early meteorological observations as hydrological forcing. As the laboratory analysis on soil and water samples proceed and the number of in-situ measurements increases, different data windows are tested to improve the performances of the calibration procedure performed using PEST. In all tests a spin-up procedure is applied to mitigate the dependency of the results on the imposed initial data by repeating the first month of hydrological forcing three times. The results of the transport model using Rosetta parameters are already satisfactory in terms of VWC trends even if they are considerably shifted respect to the measured values. The calibration reduces the gap between model results and observations, but the behaviour seems to get worse in dry conditions. Improvements are achieved in the upper layer (-0.3 m) applying evapotranspiration along the root zone. The Bromide simulations agree with the infiltration behaviour: its movement is well represented up to -0.3 m, while at -0.7 m the observed values are overestimated. Ongoing investigations on the glyphosate dispersion process show limited infiltrating mass in the water collected samples.

Vegetated buffer strips (VBS) are recognized as a cost-effective way to reduce agricultural nonpoint-source pollution. In agroecosystems with high field fragmentation, only narrow VBS that partially compromise farmers' revenue are accepted. This study aimed to identify some ecosystem services as provided by VBS in terms of soil and water quality, and VBS performance in terms of wood for energy purposes. Buffer strip design (3 vs. 6 m wide) and composition were considered to define best practices for wood use at the farm level and for the local firewood market. Results showed that yearly wood pole production was 0.5 t 100 m, on average, ranging between a minimum of 0.22 t 100 m and a maximum of 0.72 t 100 m per row. Wood production had negligible effects on farmers' revenue. By contrast, water quality was enhanced, especially with 6-m-wide VBS. Specific subsidies for the maintenance of VBS increased total income despite a reduction in crop production (-17.5% in 6-m VBS with two rows). Subsidies might be better quantified at a site-specific level by taking into account all ecosystem services that are provided by VBS. Promising solutions to increase farmers' income are related to the wood seasoning process for firewood production; reducing the moisture content to

Weeds account for losses in crop yields, and this event might be exacerbated by salinity. Therefore, we investigated the responses of Chenopodium album L. and soybean (Glycine max (L.) Merr.) to salt stress, as well as interferences between species. Ten-day old plants were grown for 1 week in a single- or mixed-species set-up, either with or without 100 mM of NaCl. C. album reduced the biomass of soybean similarly to salt stress, while its growth was unaffected under any condition. C. album decreased the crop protein content when salinity was applied. This effect was ascribed to altered protein metabolism and/or N usage to produce other N metabolites, including osmolytes. The two species did not reciprocally affect the capacity to accumulate Na+, but the weed contained two-fold more Na+ in the leaves. Elevated initial K+ concentration and high K+ delivery to the shoot likely explained the better acclimation of C. album to salinity. C. album produced more phenolics and proline and exhibited greater antioxidant activity, but low lipid peroxidation, in the mixed set-up under salinity. Thus, it is possible that the weed could become more resilient to salinity when growing in a soybean field. In the long term, this might cause significant losses in soybean productivity as expected by the dramatic decline in crop protein content.

The aquifer north of Vicenza, Italy, is one of the main and most studied drinking water reservoirs within the Veneto region. The area is an intensive cropland, and monitoring of s-triazine herbicides and metabolites has been carried out since the late eighties. This study analysed the trends of atrazine (ATR), terbuthylazine (TBZ), deethyl-atrazine (DEA), and deethyl-terbuthylazine (DET) concentrations from 1987 to 2016 and related the variations of agricultural land use, herbicide load, and pesticide regulations to the residence time of pollutants in the aquifer. In total, 785 water samples collected from 82 selected check wells were analysed with high-resolution gas chromatography combined with mass spectrometry. Non-detects were substituted by one-half the limit of detection. Over the 30 years of monitoring, concentrations of all of the pollutants decreased at all sampling sites. Since the beginning, TBZ and DET residues have been systematically lower than ATR and DEA, respectively, with more than 70% of the data below the limit of detection and never exceeding the European Maximum Acceptable Concentration (MAC) for a single pesticide (0.1 μg/L). The highest concentrations of ATR and DEA showed a spatial shift along the flow direction, suggesting an increase in groundwater residence time from the recharge zone to the accumulation zone of the aquifer. The last residues of ATR were found 27 years after its ban. Although all of the concentrations were lower than those found elsewhere in Europe, the sum of s-triazines overcame the MAC in 20% of the samples. Considering the structural and toxicological similarities of s-triazines, these findings confirm the necessity of better characterisation of the toxicological risk posed by mixtures.

This study evaluates the effect of sewage amendment (SA) on the dissipation of terbuthylazine, its degradation compound desethyl-terbuthylazine, and S-metolachlor in the soil. The experiment was conducted at Padua Experimental Farm (Italy). Herbicides dissipation was evaluated in soils differently fertilized for three years: with inorganic fertilizer, with sewage sludge, and with a combination of them. Terbuthylazine and S-metolachlor were applied on sorghum as a formulated product at a dose of 2.8 L ha

Glyphosate is the most used pesticide worldwide and its impact on the environment is becoming increasingly significant. Glyphosate and its main metabolite AMPA are frequently detected in streams and rivers. In this study, an analytical method is presented that combines Ultra-High Performance Liquid Chromatography with mass spectrometry (UHPLC–ESI-MS/MS) for glyphosate and AMPA analysis in environmental water samples. The method was developed starting from an application of Waters Corporation, and involves the use of an alternative derivatizing reagent, the commercially available AccQ·Tag™ Ultra Derivatization Kit (Waters Corporation, Milford, MA, USA). The kit contains the derivatizing reagent 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). Derivatization takes place directly in the injection vial and no sample pre-concentration is needed. The derivatization is simple, quick and robust, which fits well within the needs of a routine method for the analysis of glyphosate and AMPA. Derivatized glyphosate and AMPA were recorded in positive ion mode. The method demonstrates a good linear relationship in the concentration range from 0.2 μg/L for glyphosate and 0.05 μg/L for AMPA to 100 μg/L and an accurate recovery. The method developed has been successfully applied to the determination of glyphosate and AMPA in 23 runoff water samples collected from a field in the Po Valley (North-East Italy), an agricultural area where glyphosate is widely used.

Glyphosate is the most common herbicide worldwide, and its impact on the environment has increasingly been scrutinized. Glyphosate-based formulations can contain co-formulants, among which are surfactants. This study aimed to investigate whether the presence of an alkyl polyglucoside-based surfactant, Triton CG-110, affects the adsorption, leaching, and mineralisation of glyphosate in the soil. The experiments were conducted in two soils with different textures (sandy and clay) and in washed sand. Glyphosate and surfactant mixtures were applied at realistic field rates. Because of ponding and scarce leaching from the field soil, the leaching experiments were conducted only with washed sand. The results indicate a reduction of glyphosate adsorption in washed sand (from Kf = 13.5 to 3.99 μg1−1/n (ml)1/n g−1) and in sandy soil (from Kf = 165 to 90.8 μg1−1/ n (ml)1/n g−1) when using a Triton CG-110 concentration of 0.5 %, which corresponds to that of a spraying solution applied in the field, whereas adsorption in clay soil was unaffected. Triton CG-110 did not significantly affect glyphosate leaching in washed sand or mineralisation in any of the tested soils. The results indicate that Triton CG-110 is unlikely to significantly affect the environmental fate of glyphosate in the soil at environmentally relevant concentrations.

This study evaluates the dissipation of terbuthylazine, metolachlor, and mesotrione at different depths in soils with contrasting texture. The field trial was conducted at the Padua University Experimental Farm, north-east Italy. The persistence of three herbicides was studied in three different soil textures (clay soil, sandy soil, and loamy soil) at two depths (0-5 and 5-15 cm). Soil organic carbon content was highest in the clay (1.10%) followed by loam (0.67%) and sandy soil (0.24%); the pH of soils was sub-alkaline. Terbuthylazine, metolachlor, and mesotrione were applied on maize as a formulated product (Lumax®) at a dose of 3.5 L ha-1. Their dissipation in the treated plots was followed for 2 months after application. The concentrations of herbicides were analyzed by liquid chromatography-mass spectrometry. The dissipation of terbuthylazine, metolachlor, and mesotrione could be described by a pseudo first-order kinetics. Terbuthylazine showed the highest DT50, followed by metolachlor and mesotrione. Considering the tested soil, the highest DT50 value was found in clay soil for terbuthylazine and metolachlor, whereas for mesotrione there was no difference among soils. Significant differences were found between the two soil depths for terbuthylazine and metolachlor, whereas none were found for mesotrione. These results suggest that soil texture and depth have a strong influence on the dissipation of terbuthylazine and metolachlor, whereas no influence was observed on mesotrione because of its chemical and physical properties.

Ecosystem services provided by wetland systems presently play a pivotal role in intensive cropland as water purification from agricultural pollution. A field trial was conducted in 2014 to evaluate herbicide runoff reduction and retention using a 0.32 ha constructed surface flow wetland (CSFW) at the outlet of a 6 ha agricultural basin. To simulate an extreme pulse contamination, the CSFW was flooded with a runoff contaminated with metolachlor, and terbuthylazine and two other subsequent floods with pure water were applied 21 and 65 days later. Results show that the CSFW can reduce runoff concentration of metolachlor and terbuthylazine by a factor of 45–80 even in extreme flooding conditions. Herbicides retention in the CSFW was reversible, and the second and third floods mobilized 14–31 and 3.5–7.0% respectively, of the amount detected in the first flood. The CSFW performs a high buffer capacity for herbicides, capable to provide water purification service, protecting downstream surface water. Moreover, mitigation capacity of a CSFW for a heavy runoff from a 10 ha basin is 90% for every 50 m in length of a 15 m wide wetland. This confirms that the implementation of CSFWs in agro-systems can improve the sustainability of agricultural production.

Background and Purpose: Velvetleaf seed longevity and prolonged emergence complicate assessing appropriate time for its control. Estimating biological parameters (base temperature and base water potential) is a first step towards development of emergence predictive model for this weed species in summer crops. Since, development of new model is time consuming, the aim of the research was to provide the data set of biological thresholds for Croatian ecotype and then to compare it with Italian velvetleaf thresholds to assess the implementation of AlertInf predictive weed emergence model from Italy to Croatia. Materials and methods: Laboratory experiments were conducted with 100 seeds per three replicates at seven constant temperatures (4, 8, 12, 16, 20, 24, 28°C) to estimate base temperature (Tb) and at seven water stress levels (0.00, -0.05, -0.10, -0.25, -0.38, -0.50, -0.80, -1.00 MPa) to estimate base water potential (Ψb). Results: The highest germination occurred at temperature > 20°C with 3.6 days and at water stress level >- 0.25 MPa with 4.9 days to complete 50% of germination (t50). The slowest t50 occurred at 4°C (41.9 days) and < -0.38 MPa (10.1 days). Estimated Croatian velvetleaf biological parameters are: 4.5°C (Tb) and – 0.67 MPa (Ψb) with no significant difference compared to Italian ecotype, according to 95% confidence intervals overlapping. Conclusion: The results indicate that it could be possible to implement AlertInf model from Italy to Croatia for this weed species without additional adjustment. Nevertheless, next step of this implementation should include validation of estimated results in the field conditions. Key words: invasive weed species, velvetleaf, germination modelling, integrated weed management, base temperature, base water potential

Vegetative filter strips reduce herbicide runoff from cultivated fields owing to the ability of vegetation to delay surface runoff, promote infiltration, and adsorb herbicides. Previous research has shown that the annual runoff of each herbicide is typically less than 1 g ha-1. A model for the detection of the return period of rainfall events was recently proposed for a site in the north-eastern Po Valley, Italy. The return period model suggested that most of the herbicide loss by runoff (about 98%) is caused by a few, or even just one, extreme rainfall event with a return period of about 25-27 years, whereas ordinary events (4-5 each year) account for the rest. The present study aims to validate that model by comparing model predictions with the experimental results obtained in the 2010-2011 sampling season (independent test data), and to evaluate the effectiveness of the VFS. In addition, a 7-yr dataset of metolachlor and terbuthylazine concentration in real runoff events is summarised in order to highlight the medium-term magnitude of the pollution. Results show that on the Po Valley plain, 3-4 runoff events of low intensity are expected in spring-summer and that the consequent annual runoff of the herbicides metolachlor and terbuthylazine is about 0.5-0.7 g ha-1 yr-1. A summary shows that, owing to their chemical-physical properties, concentrations of the two herbicides are similar, both varying from about 0.01-300 microg l-1, with a potential pulse-like exposure risk for aquatic communities in waterways. This study showed that vegetative filter strips can reduce herbicide transfer to surface water by 90-98%, and should be suggested for environmental schemes at field and catchment scale.

Weed emergence models require biological parameters such as base temperature for germination, determination of which is costly and time-consuming. Transferability of these parameters across different populations may therefore represent one of the main constraints for the development and practical use of emergence models at a large scale. A collaborative project was undertaken to assess the interpopulation variability of base temperature for germination in different European populations of velvetleaf and jimsonweed and evaluate possible applicative consequences in terms of weed control. Seeds were collected in Italy, Portugal, and Spain, and each population was then sown in every country, obtaining nine seed batches named as experimental lots. Base temperature for germination was estimated for each experimental lot to calculate lot-specific accumulation of growing degree days (GDD) under three dissimilar climatic scenarios. Threshold date (TD50) was calculated as the date when GDD accumulation of a given experimental lot surpassed the values corresponding to 50% of cumulative field emergence of seedlings. GDD accumulation and TD50were then used as indicators to identify differences among experimental lots within each climatic scenario. No significant differences were detected among base temperatures estimated for velvetleaf experimental lots or among their patterns of accumulation of GDD and TD50values within climatic scenarios. Each value of base temperature determined for a single experimental lot could therefore be adopted to model germination for all the lots regardless of the population of origin or cultivation site. In contrast, the population of origin affected the base temperature for jimsonweed, with significantly higher values for experimental lots of the Portuguese population. From an applicative perspective, differences among patterns of accumulation of GDD and TD50of several experimental lots within each climatic scenario suggest the need to use population-specific values as base temperature for germination and emergence modeling of jimsonweed.

The exotic species Bidens frondosa is rapidly spreading in northern Italian arable fields, while Bidens tripartita, a native congeneric, shows less invasive capacity. To characterise and model the phenology of the two species, a two-year study was conducted involving sowings at 15-day intervals between March and August. The length of the sowing-emergence phase was well described by a simple thermal model, with a base temperature of 4.5 oC, for both species. A multiplicative photothermal model was found to be the best for the emergence-flowering phase. B. frondosa resulted as being less macrothermal and more sensitive to photoperiod. The flowering-maturity phase lasted for 30-32 days, on average, and was well described by a model based on soil water availability: this phase shortens when there is a lack of water, particularly in B. tripartita. The more relevant differences between the two species seem to be related to the vegetative phase length, which varied from 150 to 46 days and from 123 to 42 days in B. frondosa and B. tripartita, respectively. Thanks to the high elasticity of its vegetative phase, B. frondosa can grow taller than B. tripartita and acquire higher competitivity and seed production potential, both relevant factors in determining the success of a species.

Narrow vegetative filter strips proved to effectively reduce herbicide runoff from cultivated fields mainly due to the ability of vegetation to delay surface runoff, promote infiltration and adsorb herbicides. A field trial was conducted from 2007 to 2009 in north-east Italy in order to evaluate the effectiveness of various types of vegetative filter strips to reduce spring-summer runoff of the herbicides mesotrione, metolachlor and terbuthylazine, widely used in maize, and to evaluate the effect of the rainfall characteristics on the runoff volume and concentration. Results show that without vegetative filter strip the herbicide load that reaches the surface water is about 5–6 g ha −1 year −1 for metolachlor and terbuthylazine (i.e. 0.5–0.9% of the applied rate), confirming that runoff from flat fields as in the Po Valley can have a minor effect on the water quality, and that most of the risk is posed by a few, or even just one extreme rainfall event with a return period of about 25–27 years, causing runoff with a maximum concentration of 64–77 μg L −1 . Mesotrione instead showed rapid soil disappearance and was observed at a concentration of 1.0–3.8 μg L −1 only after one extreme (artificial) rainfall. Vegetative filter strips of any type are generally effective and can reduce herbicide runoff by 80–88%. Their effectiveness is steady even under severe rainfall conditions, and this supports their implementation in an environmental regulatory scheme at a catchment or regional scale.

Loddo D, Masin R, Otto S & Zanin G (2011). Estimation of base temperature for Sorghum halepense rhizome sprouting. Weed Research 52, 42–49. Summary Sorghum halepense is a rhizomatous perennial summer weed. It spreads by seeds and rhizomes that form ramets. The development of predictive models for ramet emergence (RE) from rhizomes may provide important information about their seasonal dynamics and consequently for the timing of control operations. The aim of this work was to analyse the effect of temperature on S. halepense rhizome sprouting (RS) and to estimate its base temperature, which is the first step for creating mathematical models to predict RE. Rhizomes collected from two North Italian populations were incubated at several constant temperatures. The total number of ramets, sprouted rhizomes and their ratio (ramet/sprouted rhizome) were calculated. The influence of temperature on sprouting performances was analysed. Base temperature was calculated using two methods: the reciprocal time of 50% RS (method) and RE (method). Confidence limits (at 0.95 level) were defined for each estimated base temperature using a bootstrap method. Base temperatures were compared to verify whether there were differences between populations and methods. Results indicated a significant stimulating effect of temperature on S. halepense rhizome performances. Estimated base temperatures did not differ between populations, nor between methods within a population (Padova RS 9.7 ± 1.25°C (confidence limits), RE 10.0 ± 1.28°C, Mantova RS 8.0 ± 1.89°C and RE 9.7 ± 1.23°C). The same thresholds may consequently be adopted for thermal time models for the two populations. These results also suggest that both methods (RE and RS) can be used without distinction to estimate the rhizome base temperature.

Summary We reviewed studies aimed at understanding functional relationships between weeds and arthropods in agroecosystems as influenced by biodiversity at different scales, with the main goal of highlighting gaps in knowledge, research methods and approaches. We first addressed: (i) the regulation of arthropod communities by weed diversity at genetic, species and habitat levels, (ii) the regulation of weed communities by arthropods through seed predation and dispersal and (iii) belowground weed-insect interactions. We then focussed on methodologies to study weed–arthropod interactions in agricultural landscapes and discuss techniques potentially available for data analysis and the importance of joint weed–arthropod trend detection. Lastly, we discuss the implications of research findings for biodiversity conservation policies (agri-environmental schemes) and suggest some priorities for future work. Results showed that to date research has largely ignored weed–arthropod interactions in agricultural landscapes. No information is available on the role of weed genetic diversity as driver of weed–arthropod interactions, whereas studies on effects of species and habitat diversity often lack a functional perspective and ⁄ or a spatial component. Also, information on how management of the wider agricultural biotope might express positive weed– arthropod functional interactions is scarce. Another area worth being explored is the relationship between weed-leaf ⁄ root herbivores and beneficial arthropods. Tools for spatial data analysis might be useful for elucidating weed–arthropod interactions in agricultural landscapes, but some methodological aspects, e.g. the definition of the most appropriate experimental design and sampling scale ⁄ frequency, must be refined. New studies on weed–arthropod interactions should encompass an explicit spatial component; this knowledge is particularly important for improving IPM ⁄ IWM systems and designing more targeted agri-environmental

Otto S, Loddo D & Zanin G (2010). Weed-poplar competition dynamics and yield loss in Italian short-rotation forestry. Weed Research50, 153–162. Summary In recent years there has been increasing interest in short-rotation poplar plantations for biomass production and cropping techniques and weed control strategies are being developed. Slow initial poplar growth can favour weed infestation and so there is a need for appropriate timing of weed control, based on an understanding of the competitive relationship and dynamics between poplar and weeds. A field experiment with annual and biennial crop cycles was conducted over two years. A 35 cm wide within-row weedy strip was allowed to develop as the basis for competition. Yield data were fitted with sigmoidal equations, in order to find the critical point (CP) and critical period of weed control (CPWC), using thermal time as the independent variable. Results showed that poplar is very sensitive to weed competition, especially in the first growing season after planting or cutting, and that competition can cause important yield losses. In the annual cycle, the CP corresponds to a yield loss of 26% and 8% in the first and second growing season respectively; in the biennial cycle the CP corresponds to a yield loss of 29%. Furthermore, the CPWC is long. For example, in the first year, based on a 5% yield loss, it lasts from 30 to 84 days after planting. This makes effective weed control difficult to achieve only using a pre-emergence herbicide, and thus necessitates a post-emergence treatment, either with herbicides or inter-row cultivation. These results, together with the inability of the crop to recover from damage, mean that resources must be invested in weed control soon after the beginning of the cropping cycle.

Summary Seventeen Italian experiments relating to maize, soyabean and durum wheat were used to analyse the variability of duration of tolerated competition (DTC) and weed-free period (WFP) curves across reasonably homogeneous areas. The data sets were analysed by regression analysis using four models relating yield loss to weed density, time of emergence and removal. These models differ in the way they account for the effect of time of weed removal on potential competitiveness. A sigmoidal relationship between these two variables appears necessary. The model with the best overall performance was then used to test the stability of the parameters that give the shape of the curve in relation to time of emergence and removal. This was done by comparing a full model with shape parameters specific to each experiment and a reduced model with a common set of parameters for all the experiments referring to a specific crop. For all three crops, the residual sum of squares of the reduced model did not increase significantly, indicating that, across tested environments, the yield loss caused by mixed weed infestations can be expressed by a single set of parameters relating weed competitivity to time of emergence and removal. For a given area, it should therefore be possible to predict yield loss on the basis of a quite limited set of experiments, thus greatly simplifying the development and use of decision support systems (DSS).

In intensive agricultural systems runoff is one of the major potential diffuse pollution pathways for pesticides and poses a risk to surface water. Ditches are common in the Po Valley and can potentially provide runoff mitigation for the protection of watercourses. The effectiveness depends on ditch characteristics, so there is an urgent need for site-specific field trials. The use of a fugacity model (multimedia model) can allows recognition of the mitigation main processes. A field experiment was conducted in order to evaluate the mitigation capacity of a typical vegetated ditch, and results were compared with predictions by a fugacity model. To evaluate herbicide mitigation after an extreme runoff, the ditch was flooded with water containing mesotrione, S-metolachlor and terbuthylazine. Two other subsequent floods with uncontaminated water were applied 27 and 82 days later to evaluate herbicides release. Results show that the ditch can immediately reduce runoff concentration of herbicides by at least 50% even in extreme flooding conditions. The half-distances were about 250 m. As a general rule, a runoff of 1 mm from 5 ha is mitigated by 99% in 100 m of vegetated ditch. Herbicides retention in the vegetated ditch was reversible, and the second flood mobilized 0.03 0.2% of the previous one, with a concentration below the drinking water limit of 0.1 microg/ L. No herbicide was detected in the third flood, because the residual amount in the ditch was too low. Fugacity model results show that specific physical-chemical parameters may be used and a specific soil-sediment-plant compartment included for modelling herbicides behaviour in a vegetated ditch, and confirm that accumulation is low or negligible for herbicides with a half-life of 40 days or less. Shallow vegetated ditches can thus be included in a general agri-environment scheme for the mitigation of pesticides runoff together with wetlands and linear buffer strips. These structures are present in the landscape, and their environmental role can be exploited by proper management.

In intensive agricultural systems spray drift is one of the major potential diffuse pollution pathways for pesticides and poses a risk to the environment. There is also increasing concern about potential exposure to bystanders and passers-by, especially in fragmented landscapes like the Italian pre-Alps, where orchards and vineyards are surrounded by residential houses. There is thus an urgent need to do field measurements of drift generated by air-blast sprayer in vineyards, and to develop measures for its reduction (mitigation). A field experiment with an "event method" was conducted in north-eastern Italy in no-wind conditions, in the hilly area famed for Prosecco wine production, using an air-blast sprayer in order to evaluate the potential spray drift from equipment and the effectiveness of some practical mitigation measures, either single or in combination. A definition of mitigation is proposed, and a method for the calculation of total effectiveness of a series of mitigation measures is applied to some what-if scenarios of interest. Results show that low-drift equipment reduced potential spray drift by 38% and that a fully developed vine curtain mitigated it by about 70%; when the last row was treated without air-assistance mitigation was about 74%; hedgerows were always very effective in providing mitigation of up to 98%. In conclusion, spray drift is not inevitable and can be markedly reduced using a few mitigation measures, most already available to farmers, that can be strongly recommended for environmental regulatory schemes and community-based participatory research.

Summary Digitaria sanguinalis, Eleusine indica, Setaria glauca and S. viridis are troublesome summer annual weeds in turf. For taking rational decisions on the necessity for the level and type of weed management, it is important to know when weeds are ready to emerge (dormancy status) and also how long weed seeds can survive in the soil. Seeds of these four species were buried 4.0–4.5 cm deep in steel mesh net bags placed under permanent turf and periodically exhumed for 3 years to evaluate viability and determine the dormancy/non-dormancy cycle. D. sanguinalis, S. glauca and S. viridis showed the typical dormancy cycle of summer annual species, and their seed viability declined completely after 3 years of burial. In contrast, E. indica demonstrated unusual behaviour, with long persistence and no dormancy.

DOI: http://dx.doi/10.1065/espr2006.01.016 Agricultural practices can affect the quality of aquifers given that they are often located in cropped areas, so significant amounts of pesticides can be found in the water. In particular, triazine herbicides are always carefully checked by the official monitoring systems. The goal of this study was to find the mean concentration of terbuthylazine in an Italian aquifer and to set up a mass balance of this compound. Terbuthylazine concentrations in the aquifer were measured in various check-wells during 1998–2004, and the value of censored data were estimated using a Gompertz inverse in order to evaluate the overall mean concentration. The total terbuthylazine load in the recharge area was calculated on the basis of surveys of cropped land and the main weed control techniques applied in the area. Data on aquifer water balance were obtained from previous studies. The herbicide terbuthylazine applied in the recharge zone can be transported by surface water and enter the aquifer. Detected concentrations were always well below the EU drinking water limit and the fraction that can reach the groundwater under normal cropping practices is small, very likely less than 0.2%. The use and application rates of pesticides should be strictly regulated in recharge areas. Vegetated buffer strips can mitigate the impact of herbicides on surface water through reducing drift and early-spring runoff. Attention should also be paid to the fate of the main metabolites from soil biochemical processes.

Buffer strips are an efficient and economical way to reduce agricultural nonpoint source pollution. Local researches are necessary to gain information on buffer performance, with particular emphasis on narrow buffers. The effect of a 6 m buffer strip (BS) in reducing runoff, suspended solids and nutrients from a field growing maize, winter wheat and soybean was assessed in a field experiment conducted in North-East Italy during 1998–2001. The BS was composed of two rows of regularly alternating trees (Platanus hybrida Brot.) and shrubs (Viburnum opulus L.), with grass (Festuca arundinacea L.) in the inter-rows. The BS reduced total runoff by 78% compared to no-BS, in which cumulative runoff depth was 231 mm over 4 years. With no-BS runoff appeared to be influenced mostly by total rainfall, while with BS maximum rainfall intensity was more important. The filtering effect of the BS reduced total suspended solids (TSS), particularly after the second year, when the median yearly concentrations ranged from 0.28 to 0.99 mg L−1 and were smaller than 0.14 mg L−1, with no-BS and with BS respectively. The combination of lower concentrations and runoff volumes significantly reduced TSS losses from 6.9 to 0.4 t ha−1 over the entire period. A tendency to increased concentrations of all forms of N (total, nitrate and ammonium) while passing through the BS was observed, but total N losses were reduced from 17.3 to 4.5 kg ha−1 in terms of mass balance. On the contrary, P concentrations were unmodified (soluble P), or lowered (total P) by the BS, reducing total losses by about 80%. The effect on total P, composed mainly of sediment-bound forms, was related to particulate settling when passing through the BS. A numerical index (Eutrophic Load Index), integrating water quality and runoff volumes, was created to evaluate the eutrophication risk of runoff with or without the BS. It showed that the BS effect was mostly due to a reduction of runoff volumes rather than improving the overall water quality.

Introduction In intensive agriculture areas the use of pesticides can alter soil properties and microbial community structure with the risk of reducing soil quality. Materials and Methods In this study the fatty acid methyl esters (FAMEs) evolution has been studied in a factorial lab experiment combining five substrates (a soil, two aged composts and their mixtures) treated with a co-application of three pesticides (azoxystrobin, chlorotoluron and epoxiconazole), with two extraction methods, and two incubation times (0 and 58 days). FAMEs extraction followed the microbial identification system (MIDI) and ester-linked method (EL). Results and Discussion The pesticides showed high persistence, as revealed by half-life (t1/2) values ranging from 168 to 298 days, which confirms their recalcitrance to degradation. However, t1/2 values were affected by substrate and compost age down to 8 days for chlorotoluron in S and up to 453 days for epoxiconazole in 12M. Fifty-six FAMEs were detected. Analysis of variance (ANOVA) showed that the EL method detected a higher number of FAMEs and unique FAMEs than the MIDI one, whereas principal component analysis (PCA) highlighted that the monosaturated 18:1ω9c and cyclopropane 19:0ω10c/19ω6 were the most significant FAMEs grouping by extraction method. The cyclopropyl to monoenoic acids ratio evidenced higher stress conditions when pesticides were applied to compost and compost+soil than solely soil, as well as with final time. Conclusion Overall, FAMEs profiles showed the importance of the extraction method for both substrate and incubation time, the t1/2 values highlighted the effectiveness of solely soil and the less mature compost in reducing the persistence of pesticides.

The mechanisms of herbicide resistance were investigated in two diclofop-methyl-resistant Lolium spp. populations from central Italy, Roma ’94 and Tuscania ’97. These two populations were compared with two susceptible Italian populations (Vetralla ’94, Tarquinia ’97) and a resistant and a susceptible population from Australia, SLR31 and VLR1. The activity of acetyl Co-A carboxylase (ACCase) extracted from susceptible (S) or resistant (R) individuals from the Italian populations was inhibited by both aryloxyphenoxypropanoate (diclofop acid and fluazifop acid) and cyclohexanedione (sethoxydim) herbicides. Diclofop-methyl was rapidly de-esterified to diclofop acid at a similar rate in both R and S populations. In all populations, diclofop acid was subsequently degraded to other metabolites. The rate of degradation of diclofop acid was not significantly faster in R than in S populations; however, diclofop acid was degraded more completely in Roma ’94 and Tuscania ’97 compared with the S populations. Application of the mixed-function oxidase inhibitor 1-aminobenzotriazole (ABT) significantly enhanced diclofop-methyl toxicity towards both R populations, but not in S populations. However, enhanced herbicide metabolism does not completely account for the measured resistance level. A mechanism other than an altered ACCase and enhanced herbicide metabolism appears to be responsible for resistance to diclofop-methyl in Roma ’94 and Tuscania ’97.

Populations of Lolium spp. collected in central Italy were screened for resistance to acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicides and compared with known susceptible and resistant Lolium rigidum (Gaud.) populations from Australia. Populations Roma’94 and Tuscania’97 were up to 8- and 7.5-fold more resistant to diclofop-methyl, respectively, than susceptible populations in pot experiments. However, populations Tarquinia’97 and Vetralla’94 were not resistant. Diclofop-methyl resistance levels in the Italian populations were lower than in the Australian populations SLR31 and WLR96 (16.5 and > 64 times more resistant than S respectively). In an agar germination test, Tuscania’97 showed low levels of cross-resistance to fluazifop-p-butyl, whereas no cross-resistance was found in the Roma’94 population.