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Alternate wetting and drying (AWD) is considered as an effective water-saving practice for rice cultivation widely applied across the world. Although AWD can reduce global warming potential compared to continuous flooding (CF), it may have negative effects on N availability for crop by promoting N losses (nitrification-denitrification, leaching) and immobilization, due to the frequent soil redox cycling. By means of a growth chamber pot experiment and a 15N stable isotope approach we investigated the interactions between water, crop residue and fertilizer N management on the contribution of different N sources (i.e. fertilizer, rice straw, soil) to rice plant N uptake. We hypothesized that with respect to CF, AWD will decrease plant uptake of fertilizer (FDN), straw (StDN), and soil (SDN) derived N due to greater losses, greater microbial N immobilization during residue turnover under oxic conditions, and less N supply from soil organic matter (OM) desorbed under reducing conditions. Moreover, we hypothesized that the underlying processes will be influence by the timing of straw addition with respect to flooding and the temporal distribution of mineral N application.Rice was grown for 60 d in a factorial setup including: (i) two water regimes: CF for 60 d vs. AWD (30 d of flooding followed by 30 d of alternating conditions involving 3 drain-flood cycles), and (ii) three straw and fertilizer managements that involved a combination of straw addition (10 Mg ha-1) 30 or 60 d before seeding (S30 and S60, respectively), and N fertilization (ammonium sulfate) split between pre-seeding and tillering in 60+60 or 80+40 kg N ha-1, such that treatments compared were S30-N60-N60, S30-N80-N40 and S60-N60‑N60. 15N-enriched fertilizer and straw were used in separate replicated setups to quantify the relative contribution of FDN, StDN and SDN to plant N uptake, as well as fertilizer use efficiency (FUE).Plant N was mainly soil and fertilizer-derived (≈ 58 and 40%, respectively), while straw only contribute a minor amount (< 3%). Although AWD reduced total N uptake by about 10-13% with respect to CF, FDN and FUE were only slightly affected by water management, suggesting that differences in N nutrition did not depend exclusively on fertilizer N losses. SDN contributed more to plant nutrition in CF than in AWD, particularly when straw was incorporated in proximity to flooding. The combination of a fresh OM supply and reducing conditions under CF favoured the reductive dissolution of Fe oxides and desorption of soil OM that increase soil N supply via mineralization. StDN contributed less to plant nutrition in AWD than in CF albeit the higher mineralization rates we expected with more frequent oxic conditions. We attributed this to a higher microbial N demand under aerobic conditions that leads to a greater immobilization SDN during decomposition. The higher SDN and StDn for N60-N60 treatment with respect to N80-N40 suggested that an equilibrated splitting of N fertilizer between pre‑seeding and tillering stages could favor microbial activity under AWD improving straw degradation and soil N release.This research was funded by the Lombardy Region through the project RISWAGEST

An index-based approach for a comprehensive evaluation of the potential risk for active substances and their mixtures to impact the environment was developed. Some of the indices considered already exist (PRISW-1, Priority Index), while others were created ex novo from indicators available on open-source platforms (PESTi, ECOi, AGROi). These indices maybe used for an evaluation before use of pesticides by farmers and advisers. The present approach was initially validated for herbicides in maize crops, but it can readily be applied to other PPPs and crops. PESTi index underline the physical and chemical characteristics as a whole, not considering the impact of other factors such as application rate or period of application. Hence, this index may underestimate the risk associated to a certain chemical. AGROi has a precautionary approach. The risk associated to a specific mixture derives from a combination of intrinsic characteristics of the chemicals, agronomic impacts, regulation restrictions and potential hazard to water compartment. The ECOi index is focused on the ecotoxicological impact against non-target organisms. The helpfulness of this index stands in its ability to easily discriminate the ecotoxicological impact of chemicals using indicators commonly available in literature and without making complex calculations. PRISW-1 Index discriminate active substances according to their risk against three representative non-target organisms. However, due to the intrinsic characteristics of each pesticide, a high PRISW-1 value could not always mean an easy movement of the chemical via runoff waters. The information deriving from Priority index may certainly help public authorities to select chemicals to be detected in water monitoring campaigns. The application of these indices may represent a valid decision tool for public stakeholders in defining agricultural measures to reduce the externalities of pest control.

In this work a novel nano-formulation is proposed to control leaching and volatilization of a broadly used herbicide, dicamba. Dicamba is subject to significant leaching in soils, due to its marked solubility, and to significant volatilization and vapor drift, with consequent risks for operators and neighbour crops. Natural, biocompatible, low-cost materials were employed to control its dispersion in the environment: among four tested candidate carriers, a nanosized natural clay (namely, K10 montmorillonite) was selected to adsorb the pesticide, and carboxymethyl cellulose (CMC), a food-grade biodegradable polymer, was employed as a coating agent. The synthesis approach is based on direct adsorption at ambient temperature and pressure, with a subsequent particle coating to increase suspensions stability and control pesticide release. The nano-formulation showed a controlled release when diluted to field-relevant concentrations: in tap water, the uncoated K10 released approximately 45% of the total loaded dicamba, and the percentage reduced to less than 30% with coating. CMC also contributed to significantly reduce dicamba losses due to volatilization from treated soils (e.g., in medium sand, 9.3% of dicamba was lost in 24 h from the commercial product, 15.1% from the uncoated nanoformulation, and only 4.5% from the coated one). Moreover, the coated nanoformulation showed a dramatic decrease in mobility in porous media (when injected in a 11.6 cm sand-packed column, 99.3% of the commercial formulation was eluted, compared to 88.4% of the uncoated nanoformulation and only 24.5% of the coated one). Greenhouse tests indicated that the clay-based nanoformulation does not hinder the dicamba efficacy toward target weeds, even though differences were observed depending on the treated species. Despite the small (lab and greenhouse) scale of the tests, these preliminary results suggest a good efficacy of the proposed nanoformulation in controlling the environmental spreading of dicamba, without hindering efficacy toward target species.

11 Pág., Over the last 30 years, many studies have surveyed weed vegetation on arable land. The 'Arable Weeds and Management in Europe' (AWME) database is a collection of 36 of these surveys and the associated management data. Here, we review the challenges associated with combining disparate datasets and explore some of the opportunities for future research that present themselves thanks to the AWME database. We present three case studies repeating previously published national scale analyses with data from a larger spatial extent. The case studies, originally done in France, Germany and the UK, explore various aspects of weed ecology (community composition, management and environmental effects and within-field distributions) and use a range of statistical techniques (canonical correspondence analysis, redundancy analysis and generalised linear mixed models) to demonstrate the utility and versatility of the AWME database. We demonstrate that (i) the standardisation of abundance data to a common measure, before the analysis of the combined dataset, has little impact on the outcome of the analyses, (ii) the increased extent of environmental or management gradients allows for greater confidence in conclusions and (iii) the main conclusions of analyses done at different spatial scales remain consistent. These case studies demonstrate the utility of a Europe-wide weed survey database, for clarifying or extending results obtained from studies at smaller scales. This Europe-wide data collection offers many more opportunities for analysis that could not be addressed in smaller datasets; including questions about the effects of climate change, macro-ecological and biogeographical issues related to weed diversity as well as the dominance or rarity of specific weeds in Europe., This work was made possible via the Weeds and Biodiversity working group of the European Weed Research Society. This project was funded under a Rothamsted Research and BBSRC grant number BB/W510543/1. Helen Metcalfe was partly supported by the Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) research programme NE/N018125/1 LTS-M (ASSIST). Jana Bürger's work on this project was supported by Deutsche Forschungsgemeinschaft DFG (grant number BU 3097/1-1).

Questions: Two scientific disciplines, vegetation science and weed science, study arable weed vegetation, which has seen a strong diversity decrease in Europe over the last decades. We compared two collections of plot-based vegetation records originating from these two disciplines. The aim was to check the suitability of the collections for joint analysis and for addressing research questions from the opposing domains. We asked: are these collections complementary? If so, how can they be used for joint analysis?. Location: Europe. Methods: We compared 13 311 phytosociological relevés and 13 328 records from weed science, concerning both data collection properties and the recorded species richness. To deal with bias in the data, we also analysed different subsets (i.e., crops, geographical regions, organic vs conventional fields, center vs edge plots). Results: Records from vegetation science have an average species number of 19.0 ± 10.4. Metadata on survey methodology or agronomic practices are rare in this collection. Records from weed science have an average species number of 8.5 ± 6.4. They are accompanied by extensive methodological information. Vegetation science records and the weed science records taken at field edges or from organic fields have similar species numbers. The collections cover different parts of Europe but the results are consistent in six geographical subsets and the overall data set. The difference in species numbers may be caused by differences in methodology between the disciplines, i.e., plot positioning within fields, plot sizes, or survey timing. Conclusion: This comparison of arable weed data that were originally sampled with a different purpose represents a new effort in connecting research between vegetation scientists and weed scientists. Both collections show different aspects of weed vegetation, which means the joint use of the data is valuable as it can contribute to a more complete picture of weed species diversity in European arable landscapes., The work on this project was supported by Deutsche Forschungsgemeinschaft DFG (grant number BU 3097/1-1 for Jana Bürger), Czech Science Foundation (grant number 19-28491X for Milan Chytrý and Zdeňka Lososová), and by Slovenian Research Agency (research core funding No. P1-0236 for Urban Šilc and Young researcher programme for Filip Küzmič).

Weedy rice (Oryza sativa L.) is a troublesome rice (Oryza sativa L.) weed in Italy and in many other rice areas. The objective of this study was to correlate the O. sativa infestation level in northern Italy, the main European rice-growing area, with agricultural practices adopted by farmers by using data obtained from a farmer survey. In 2018 to 2019, a survey was carried out on 98 rice farms chosen to ensure different sizes, different cultivation practices, and variable degrees of O. sativa infestation. The following information was acquired: farm size; area cultivated with Clearfield® varieties; the most-adopted agronomic practices (type of tillage, crop rotation, type of sowing, water management, origin of seeds, adoption of stale seedbed, use of imazamox, presence of O. sativa resistant to imazamox); and level of O. sativa infestation: low (≤5 plants m−2), medium (>5 to 20 plants m−2), and high (>20 plants m−2). The data were analyzed through descriptive statistics and ordinal logistic regression to determine which agronomic practices influenced the level of O. sativa infestation. Farm clustering was also determined through two-step cluster analysis. Rice was cultivated as a monocrop and mainly sown in water, using purchased seeds, in plowed fields. More than half of the farms used the stale seedbed practice, and 63% adopted Clearfield® varieties, while about 45% of the farms reported imazamox-resistant O. sativa. The ordinal logistic regression underlined that use of a stale seedbed was correlated with the infestation level of O. sativa, and the two-step cluster analysis showed that the farms were mainly grouped based on the use of this technique. Most of the farms that used a stale seedbed had higher O. sativa infestation than those that did not use it, meaning that this practice was mainly applied in zones where O. sativa infestations were more serious.

Salinization is affecting many rice (Oryza sativa L.) areas worldwide and weed infestation, together with the occurrence of herbicide-resistant populations, is further limiting rice yield. This study aimed at evaluating the effect of water salinity on the emergence and seedling growth of five Italian barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] populations (three sensitive and two resistant to acetolactate synthase–inhibiting herbicides), three Italian weedy rice (Oryza sativa L.) populations (all sensitive to imazamox), and two rice varieties (the conventional ‘Baldo’ variety and the imazamox-tolerant ‘CL80’ one). In 2017, seeds were sown in alveolar trays filled with sand, a nutrient solution, and water with the following salt concentrations: 0, 50, 100, 150, 200, and 250 mM NaCl. Plant emergence (after 15 d), plant height, shoot and root weight, chlorophyll a, chlorophyll b, and carotenoid content were measured at 40 d after sowing. Echinochloa crus-galli showed a higher tolerance to salinity than O. sativa and rice. All species were affected more at the seedling stage than at emergence. A variable behavior of the herbicide-resistant populations was shown; one resistant E. crus-galli population was affected more by salinity and showed a lower emergence rate (about 20% against 40% emergence of the other populations at the highest salt concentration) and reduced seedling growth, while the other resistant population’s response was similar to that of the sensitive populations. The chlorophyll content increased as the salt content increased in all E. crus-galli populations. The highest emergence and growth reduction in O. sativa were recorded in the imazamox-tolerant rice. Rice and O. sativa were able to grow only up to 50 mM. Echinochloa crus-galli populations are probably favored under saline conditions, while lower infestation by O. sativa can be expected.

The abundance of weedy rice (Oryza sativa L.) in the soil seedbank was estimated in 2011 in Italian rice (Oryza sativa L.) fields with different histories of imidazolinone-resistant Clearfield® rice varieties (CL), non-Clearfield® varieties (NCL), and planting methods. A model was used to predict weedy rice seedbank dynamics over time under different control strategies. Soil samples were taken from 50 rice fields cultivated with CL varieties consecutively for 0, 1, 2, or 3 yr, and weedy rice seedbank data were used in a model considering eight scenarios: (A) rice monoculture with CL and NCL varieties in alternate years; (B) 2 yr of CL, followed by 1 yr with NCL; (C) 3 yr of CL followed by 1 yr of NCL; (D) rice monoculture with only CL; (E) rice monoculture with only NCL; (F) 2 yr of CL followed by 1 yr of rotation with another crop (CR), and then by an additional year with NCL; (G) 1 yr of CR followed by 2 yr of CL, and then by 1 yr of NCL; (H) 2 yr of CR followed by 2 yr of CL. The weedy rice seedbank exceeded 1,000 seeds m−2 in the surveyed fields with no significant differences between rice planting methods. Highest densities were found in fields cultivated for 1 yr with CL varieties. Simulations indicated that where CL varieties were used in rice monoculture, the susceptible weedy rice seedbank was gradually reduced, producing a depletion after 17, 13, 11, and 9 yr in scenarios A, B, C, and D, respectively. The weedy rice seedbank increased in NCL monoculture (E) and declined significantly in crop rotation scenarios (F, G, H). The simulations indicated that the introduction of crop rotation is crucial for obtaining a relatively fast reduction of weedy rice seedbank and delaying the evolution of herbicide-resistant populations.

In 2002, a survey carried out in rice paddies in the Rio Grande do Sul (RS) state reported the occurrence of nine species of jointvetch (Aeschynomene). Due to their semi-aquatic habit, some species adapted to irrigated rice fields, which led to their being considered the worst broadleaf weed in RS. Although farmers have successfully implemented weed management practices, Aeschynomene plants have reportedly escaped chemical control. This study aims to identify the species of Aeschynomene that occur in rice fields in RS and to evaluate the reasons why escapes are occurring. A survey was carried out by collecting mature seeds from individual adult plants. A questionnaire on the management practices employed in each field was administered to 54 farmers and 18 extension agents, each of whom was responsible for one of the surveyed rice fields. This survey found four species of Aeschynomene are present in rice fields in RS: A. denticulata, A. indica, A. rudis, and A. sensitiva. The results suggest that the explanation for escapes may lie in the management practices adopted by farmers, which are focused on the control of weedy grasses. Escapes are also associated with problems such as the lack of irrigation uniformity and out-of-stage, late herbicide applications.

Ambrosia artemisiifolia (common ragweed) is an annual weed known to infest crops and disturbed areas, and cause human pollinosis. To examine the effect of different thermal regimens on seed germina...

Weed control is one of the most important practices for a satisfying crop performance. In organic farming, weeds are mainly controlled by using mechanical methods, which may result in incomplete crop selectivity. Maize is one of the crops for which mechanical weed control is commonly applied. To assess weed control efficacy and the possible crop injuries caused by mechanical interventions (harrowing, hoeing and ridging), a field experiment was carried out in 2013–2014 on traditional flint Italian varieties of maize (Marano, Ottofile, Pignoletto, Nostrano and the hybrid Maranello) suited for organic food production. The study included the following treatments: weed control with a spring tine harrow + hoeing and ridging (STH), manual weed removal all season long (MWR), spring tine harrowing + manual weed removal (STH + MWR) and an untreated check (CHK). In the 2 years, the experiment was carried out in two similar fields in which 60 plots (6 × 10 m) were arranged in a RCBD with three replications. Weed control efficacy was assessed by determining weed density, weed species composition and weed cover after each mechanical intervention in the STH and CHK plots. Weed diversity indices were also calculated at the final assessment. The possible crop injuries caused by mechanical means were assessed by determining maize plant height, number of leaves, and plant density after each mechanical intervention. At maturity, maize yield and other yield-related traits (1000-seed weight, hectolitre weight, and grain moisture) were determined. The results showed that the mechanical treatments lowered the weed infestation, without changing weed species dominance and slightly lowering species richness; even though they were not able to completely control the weeds. In both years, the final weed density in STH plots was of about 50 plants m−2. Better weed control was obtained when weeds were at early growth stages and with a repeated number of harrowing. Mechanical weeding did not cause significant injury in terms of plant height nor density; however, for Marano and Maranello, a delay in the crop cycle was observed as shown by the lower number of leaves in STH compared with MWR. Yield ranged from 0.3 t ha−1 for Marano CHK to 10.4 t ha−1 for the hybrid Maranello in MWR + STH. Yield and yield-related traits were not affected by mechanical weeding.

“Arable Weeds and Management in Europe” is a collection of weed vegetation records from arable fields in Europe, initiated within the Working Group Weeds and Biodiversity of the European Weed Research Society (EWRS). Vegetation-plot data from this scientific community was not previously contributed to databases. We aim to prove the usefulness of collection for large scale studies through some first analyses. We hope to assure other weed scientists who have signalled willingness to share data, and plan to construct a full data base, making the data available for easy sharing. Presently, the collection has over 60,000 records, taken between 1996 and 2015. Many more studies for potential inclusion exist. Data originate mostly from studies exploring the effect of agricultural management on weed vegetation. The database is accompanied with extensive meta-data on crop and weed management on the surveyed fields. The criteria for inclusion were a minimum amount of information on the cultivated crop, and a georeference. Most fields were surveyed repeatedly, i.e. transects, multiple random plots, or repeated visits. All surveys aimed to record the complete vegetation on the plots. Sometimes, taxa were identified only to genus level, due to survey dates very early in the vegetation period. Plant taxonomy is standardized to the Euro+Med PlantBase., B. was funded by Deutsche Forschungsgemeinschaft under the grant number BU 3097/1-1.

Weed control in rice fields has become particularly difficult because of the increased occurrence of herbicide resistance. The objective of the study was to assess in field conditions, in Italy, if...

Glyphosate is the world's most used herbicide to control weeds in tree and herbaceous crops, and in non-agricultural areas. However, health and environmental concerns, as well as the spread of weed resistance, may lead to a ban or limitations of its use. This event would necessitate that alternative weed control techniques be made available quickly. Potential chemical alternatives include herbicides authorized for the same uses as glyphosate that in this review were identified through searches of the pesticide databases of Italy, Spain, France, Germany, The Netherlands, and Estonia. Non-chemical control measures encompass mowing, tillage, and cover crops in agricultural areas and mowing, flaming, hot water, hot foam, and steam in non-agricultural areas. Examination of the data reveals that a loss of glyphosate availability would not only require more complex and expensive weed managements, but also integration of multiple weed control techniques.

Seeding rates of hybrid wheat varieties are typically much lower than conventional varieties due to their higher seed costs, which could potentially delay canopy development leading to greater weed pressures. To test whether hybrid wheat crops are more affected by weed pressure than conventional cultivars, a conventional variety (&ldquo, Illico&rdquo, ) and a hybrid (&ldquo, Hystar&rdquo, ), were compared in a three-year (2012&ndash, 2016) field study at two sites in Northern Italy. Weed infestation was mainly characterized by weeds with an early growth pattern, and in only a few seasons did the hybrid crops show a higher weed density than the conventional cultivar. Despite the lower sowing rate, hybrids were able to achieve a similar crop density to the conventional cultivar even in years of delayed sowing or dry weather conditions. Normalized Difference Vegetation Index values were generally similar between cultivars across the years, regardless of the presence of weeds, except during the springtime. Occasionally, the test weight was significantly higher in weeded plots than un-weeded plots. Overall, the two cultivars showed similar yields within the same year. These results indicate that on fields with a low weed burden, and where these weeds emerge early, cultivars may not be significantly affected by productivity losses.

Weeds that have become resistant to herbicides may threaten rice production. Rice cultivation is mainly carried out in coastal and river delta areas that often suffer salinity problems. The aims of this study were to evaluate the effects of salinity upon germination and the root and shoot seedling growth of Italian weedy rice and cultivated rice (Oryza sativa), and to find a possible correlation between salinity and herbicide resistance. Seed germination tests were conducted in Petri dishes on four imazamox-sensitive and one resistant weedy rice populations and two rice varieties: Baldo (conventional) and CL80 (imidazolinone-resistant Clearfield&reg, variety). Different salt concentrations were tested: 0, 50, 100, 150, 200, 250, 300, 350 and 400 mM NaCl. Germination percentage, germination speed, seedling root and shoot length were affected by increasing the salt concentration in all tested populations and varieties. The germination percentage was in general more affected in resistant weedy rice and CL80. In resistant weedy rice this was partially compensated by a faster germination up to 100 mM. In terms of seedling root and shoot length, CL80 and Baldo showed the highest tolerance to salt, resistant weedy rice was not able to produce seedling roots and shoots at concentrations &gt, 300 mM.

Ailanthone is a quassinoid from Ailanthus altissima (Mill.) Swingle with allelopathic properties that deserves interest for its potential use as a natural herbicide. Data about seed germination and root and hypocotyl length of two model species (Lepidium sativus L.ˈIngleseˈ and Raphanus sativus L.ˈTondo Rosso BIOˈ) treated with different concentrations of ailanthone are reported. Data derive from experiments performed in a growth chamber on filter paper, non-sterile urban soil, and a cultivation substrate for horticulture. Part of their elaboration and interpretation can be found in the research article titled “Ailanthone from Ailanthus altissima (Mill.) Swingle as potential natural herbicide” (Demasi et al., 2019). Keywords: Ailanthus altissima, Allelopathy, Quassinoid, Phytotoxicity, Natural herbicide

Ailanthone, a quassinoid from Ailanthus altissima (Mill.) Swingle, is a natural herbicide, whose use is limited by its low persistence and rapid degradation in organic substrates. Dextrin-based nanosponges (NSs) are polymers with a cage-like structure that can complex several molecules, acting as carriers or protectors. Their encapsulation efficiency can be exploited in numerous applications. Hence this study explored at first the biological activity of eight different dextrin-based NSs, synthesized with 1,1′-carbonyldiimidazole (CDI) or pyromellitic dianhydride (PYRO) (αNS-CDI, βNS-CDI, γNS-CDI, LC NS-CDI, αNS-PYRO, βNS-PYRO, γNS-PYRO, and LC NS-PYRO), towards two model species (Lepidium sativum L. and Raphanus sativus L.) in filter paper under controlled conditions in laboratory. Then, the selected dextrin-based NSs were loaded with ailanthone and applied in the concentration of 7.5 or 30 mg L−1 of ailanthone in pre-emergence on the same species, initially on filter paper and subsequently on cultivation substrate for horticulture. In all three bioassays, the number of germinated seeds and the length of developed roots and hypocotyls were evaluated. In the first bioassay, the results showed that five dextrin-based NSs promoted the germination and root elongation, thus counteracting the herbicidal effect of ailanthone. Hence, three selected formulations (αNS-CDI, γNS-CDI, and LC NS-CDI) were loaded with ailanthone, with γNS-CDI providing the highest loading capacity (1.36%) and encapsulation efficiency (55.15%). In the second bioassay, the phytotoxic activity of ailanthone was strengthen by dextrin-based NSs, always stronger by at least 58% than the pure compound across 30 days in paper, without differences between formulations. In the third bioassay, loading ailanthone in γNS-CDI also prolonged its herbicidal activity, still reducing to only 20% the germination and growth of garden cress and radish 30 and 20 days after treatment, respectively. Overall, results demonstrated that dextrin-based nanosponges can be proposed as suitable carriers in the formulation of ailanthone-based herbicide. Their use both increased and extended the phytotoxic activity of ailanthone, leading to the possibility of reducing the amount applied for each treatment, or reducing the number of herbicide treatments.

BACKGROUND Rice is a major field crop of paramount importance for global food security. However, the increased adoption of more profitable and resource-efficient direct-seeded rice (DSR) systems has contributed to greater weed infestations, including weedy rice, which has become a severe problem in several Asian regions. In this study we have developed a conceptually novel method to protect rice plants at high doses of clomazone and triallate. RESULTS The insecticide phorate applied to rice seeds provided a substantial level of protection against the herbicides clomazone or triallate. A quantity of 15 kg phorate ha−1 significantly increased the LD50 values, which were more than twofold greater than for rice plants treated only with clomazone. A quantity of 20 kg phorate ha−1 in combination with 2000 g triallate ha−1 safened rice plants (80% survival) with LD50 >3.4-fold greater than in phorate-untreated rice. Weed control efficacy was not lowered by the presence of phorate-treated rice seeds. CONCLUSION Weedy rice is one of the most damaging global weeds and a major threat to DSR systems. In this study we have developed a proof-of-concept method to allow selective weedy rice control in rice crops. We call for herbicide discovery programmes and research to identify candidate safener and herbicide combinations to achieve selective herbicide control of weedy rice and alleviate weed infestations in global rice crops. © 2016 Society of Chemical Industry

Ailanthone (Ail) is the most phytotoxic quassinoid in plant extracts of Ailanthus altissima (Mill.) Swingle, an invasive tree of Simaroubaceae with allelopathic activity. Ail has raised attention as a potential biological herbicide in weed management to reduce the impact on the environment and human health. However, high costs for its extraction and purification, and low persistence in the soil have been considered so far limits for its development as herbicide for open field applications. In this study we explored its phytotoxic activity and persistence, through five experiments, to evaluate its potential for the weed management in the horticulture sector and in urban green areas, where lower herbicide amounts are needed. Ail inhibition activity on germination and growth was evaluated on two model species (garden cress - Lepidium sativum L. - and radish - Raphanus sativus L.). Firstly, the dose-response curve between Ail concentration and index of germination was calculated in filter paper and Ail persistence along 30 days was also assessed. Afterwards, Ail bioactivity and persistence were evaluated in a non-sterile urban soil and a horticultural substrate. Ail inhibited by 80 to 90 % the plant growth already at low doses (7.5 mg L-1) in paper and soil, while higher concentrations (≥ 30 mg L-1) were necessary in the cultivation substrate to obtain similar results. Regarding the phytotoxic persistence, the two species were similarly inhibited at the first evaluation (10 days after treatment) both in paper and cultivation substrate, whereas on the longer period (20 and 30 days after treatment), radish was more affected, with growth inhibition higher than 45 % until 30 days. Results of these experiments implement the knowledge on Ail phytotoxic activity, envisioning its potential use as a biological solution for weed management in urban areas and protected cultivation environments.

The effect of elapsed time between spraying and first leaching event on the leaching behavior of five herbicides (terbuthylazine, S-metolachlor, mesotrione, flufenacet, and isoxaflutole) and two metabolites (desethyl-terbuthylazine and diketonitrile) was evaluated in a 2011-2012 study in northwest Italy. A battery of 12 lysimeters (8.4 m(2) long with a depth of 1.8 m) were used in the study, each filled with silty-loam soil and treated during pre-emergence with the selected herbicides by applying a mixture of commercial products Lumax (4 L ha(-1)) and Merlin Gold (1 L ha(-1)). During treatment periods, no gravity water was present in lysimeters. Irrigation events capable of producing leaching (40 mm) were conducted on independent groups of three lysimeters on 1 day after treatment (1 DAT), 7 DAT, 14 DAT, and 28 DAT. The series was then repeated 14 days later. Leachate samples were collected a few days after irrigation; compounds were extracted by solid phase extraction and analyzed by high-performance liquid chromatography and gas chromatography-mass spectrometry. Under study conditions, terbuthylazine and S-metolachlor showed the highest leaching potentials. Specifically, S-metolachlor concentrations were always found above 0.25 µg L(-1). Desethyl-terbuthylazine was often detected in leached waters, in most cases at concentrations above 0.1 µg L(-1). Flufenacet leached only when irrigation occurred close to the time of herbicide spraying. Isoxaflutole and mesotrione were not measured (

Experimentally applying pesticides is an important method to assess the efficacy of weed biocontrol agents, but potential direct effects of the chemicals on plant performance are controversial or unknown. We assessed how three broad-spectrum insecticides applied in combination affect the performance of the widely invasive, crop-yield reducing, allergenic common ragweed (Ambrosia artemisiifolia L.) in an insect-free environment. Spraying insecticides had no significant effects on aboveground dry weight, seed and pollen output or pollen allergenicity, and only explained 1-8% of variation in these parameters. Our insecticide treatment can hence be applied to assess biocontrol impact on biomass and reproductive output of common ragweed. As our insecticide treatment delayed senescence, however, other methods of insect exclusion should be preferred when studying common ragweed phenology.

Summary The introduction of imidazolinone-tolerant rice varieties has made selective Oryza sativa (weedy rice) control possible. We hypothesised that Italian weedy rice populations have variable degrees of susceptibility to imazamox prior to imidazolinone-tolerant variety introduction. To this end, 149 Italian weedy rice populations collected from fields never before cultivated with imidazolinone-tolerant varieties were tested in a glasshouse-based, whole-plant response screening study. Imazamox was applied to all populations post-emergence at a rate of 70 g a.i. ha−1, resulting in 70–90% shoot biomass reduction in the majority of cases. The results prompted a second study of the seedling dose response of four weedy rice populations from the initial study group. Three imidazolinone-tolerant and one conventional rice variety were also included. The seedling roots were cut six days after germination and exposed to different concentrations of imazamox. The root regrowth associated with each concentration-exposure was then measured. Imazamox concentrations to inhibit weedy rice root growth by 50% varied by about two orders of magnitude, or between 0.0018 and 0.12 mm. Even with this result, imidazolinone-tolerant varieties were at least 31.8 times less susceptible than weedy rice populations, suggesting that Italian weedy rice populations were not tolerant to imazamox before introduction of these varieties.

Ambrosia artemisiifolia (common ragweed), an annual native to North America, is now present in many European countries where it causes summer hay fever and interferes with several important crops. We investigated if common ragweed invasiveness could be explained by its leaf tissue and root exudate allelopathic potential on indicator crops (alfalfa, barley, maize, lettuce, tomato, and wheat), weeds (Echinochloa crus-galli, Solanum nigrum, Portulaca oleracea, and Digitaria sanguinalis), and common ragweed itself in laboratory and greenhouse conditions. Different residue substrates were prepared for soil incorporation and trials were conducted under both laboratory (1, 2, and 3 g residues/Parker dish) and greenhouse conditions (1.28 g residues/pot). The effect of the preparations on the germination and growth of the indicator crops and weeds were evaluated relative to soil previously used to grow A. artemisiifolia. Results showed tomato was the most sensitive indicator crop species as growth was reduced by more than 50% in both laboratory and greenhouse experiments. Lettuce root and shoot growth were also inhibited, but only when common ragweed residues, and not root exudates, were added to the substrate. Among the weeds, E. crus-galli was not affected by common ragweed while D. sanguinalis suffered a large germination reduction (90%) after incorporation of 3 g of residues. If common ragweed occurred as weed in a field, the cultivation of a less sensitive crop such as winter wheat should be considered before the cultivation of a more susceptible crop.

During the 2006/07 and 2008/09 growing seasons in Southern Brazil, we evaluated crop selectivity and weed control efficacy of clomazone on rice when applied alone or in a mixture with other pre- and post-emergence herbicides (BRS Querencia variety). All herbicide treatments caused some degree of rice injury during both years; however, in no case was the injury still visible 21 days after application. Rice injuries were observed when application rates exceeded the recommended dose, and particularly when the herbicide was applied pre-emergence. Density reduction and panicle sterility served as measures of rice injury. Echinochloa crus-galli was the primary weed; it reduced rice yields by approximately 50% compared treated plots. In both growing seasons, clomazone herbicide (400 g ai ha−1) controlled the weed 87.0%–99.6%, and it provided 8.06 t ha−1 to 9.44 t ha−1 of rice yield.