Foliar Retention Research Articles

Improving UV protection and retention of photosensitive agrochemicals: Innovative polyurethane-CeO2 hybrid pesticide microcapsules

Photolysis and poor retention significantly decrease the utilization efficiency of photosensitive agrochemicals, leading to considerable ecological and economic losses. We successfully prepared novel pyraclostrobin-loaded polyurethane-inorganic hybrid microcapsules (Pyr@KCeO2-PU MCs) with high adhesion and UV stability by interfacial polymerization. CeO2 nanoparticles (NPs) were incorporated as UV light absorbers, while a silane coupling agent (KH550) was employed for in situ crosslinking of PU with CeO2 NPs, facilitating their dispersion within the PU shell. Characterization results revealed a high encapsulation efficiency of 90 % and uniform sizes (D50 = 915 nm) for the Pyr@KCeO2-PU MCs. Optical property investigations using UV–vis spectroscopy indicated that the integration of CeO2 NPs within the PU shell produced stronger UV absorption bands compared to both Pyr technical (TC) and Pyr@PU MCs. This observation underscores the potential of CeO2 NPs as effective UV absorbers. The anti-photolysis performance of Pyr@KCeO2-PU MCs improved with the addition of CeO2 NPs, yielding a retention rate of Pyr in Pyr@KCeO2-PU MCs that was 1.90 and 1.27 times greater than that of Pyr TC and Pyr@PU MCs, respectively, under UV irradiation. Furthermore, KH550 not only facilitated crosslinking between PU and CeO2 NPs, ensuring uniform distribution of CeO2 NPs on the PU shell surface, but also enhanced wettability and foliar retention. The contact angle of Pyr@KCeO2-PU MCs (32°) was significantly lower than that of Pyr@PU MCs (84°), and Pyr retention on rice leaves was 17.5 mg/cm2 for Pyr@KCeO2-PU MCs, surpassing that of Pyr@PU MCs (9.3 mg/cm2). Additionally, Pyr@KCeO2-PU MCs exhibited superior efficacy against various plant pathogens compared to Pyr TC and Seltima. These findings highlight the potential of Pyr@KCeO2-PU MCs for enhancing pesticide utilization and offer valuable insights for the future development of PU-based pesticide formulations.

Long-lasting, UV shielding, and cellulose-based avermectin nano/micro spheres with dual smart stimuli-microenvironment responsiveness for Plutella xylostella control

The requirement to improve the efficiency of pesticide utilization has led to the development of sustainable and smart stimuli-responsive pesticide delivery systems. Herein, a novel avermectin nano/micro spheres (AVM@HPMC-Oxalate) with sensitive stimuli-response function target to the Lepidoptera pests midgut microenvironment (pH 8.0–9.5) was constructed using hydroxypropyl methylcellulose (HPMC) as the cost-effective and biodegradable material. The avermectin (AVM) loaded nano/micro sphere was achieved with high AVM loading capacity (up to 66.8 %). The simulated release experiment proved the rapid stimuli-responsive and pesticides release function in weak alkaline (pH 9) or cellulase environment, and the release kinetics were explained through release models and SEM characterization. Besides, the nano/micro sphere size made AVM@HPMC-Oxalate has higher foliar retention rate (1.6–2.1-fold higher than commercial formulation) which is beneficial for improving the utilization of pesticides. The in vivo bioassay proved that AVM@HPMC-Oxalate could achieve the long-term control of Plutella xylostella by extending UV shielding performance (9 fold higher than commercial formulation). After 3 h of irradiation, the mortality rate of P. xylostella treated by AVM@HPMC-Oxalate still up to 56.7 % ± 5.8 %. Moreover, AVM@HPMC-Oxalate was less toxic to non-target organisms, and the acute toxicity to zebrafish was reduced by 2-fold compared with AVM technical.

Polydopamine-coated matchstick-like mesoporous silica carriers for improving foliar retention and responsive pesticide release

Intelligent responsive pesticide delivery systems have gained extensive interest in enhancing utilization efficiency of pesticides and relieving environmental hazards. Herein, we developed a novel matchstick-like mesoporous silica (mSiO2) nanocarriers for pesticide delivery. The asymmetric matchstick-like mSiO2 carriers were composed by a spherical dendritic silica (SiO2) head (300 nm) and a rod-shaped tail (90 nm in length). This asymmetric structure would improve foliar retention by increasing contact area and forming topological effect between the carriers and the leaves surface. The prepared mSiO2 carriers possessed a high loading content for the insecticide dinotefuran (DNF) (23.7 %). Subsequently, polydopamine (PDA) was utilized to seal the DNF-loaded mSiO2 (DNF@mSiO2@PDA). The foliar affinity and adhesion properties of the mSiO2@PDA were enhanced due to the introduction of the hydrophilic PDA layer. The DNF@mSiO2@PDA exhibited pH-responsive release performance and the anti-UV property of loaded DNF was improved by about 10 times. Additionally, the DNF@mSiO2@PDA also exhibited high insecticidal activity due to the improving foliar wetting and affinity. Therefore, this work provides a promising strategy to increase pesticide retention on leaves and reduce pesticide chemical usage.

Lignin microcapsules prepared on the basis of flexible skeleton with high foliar retention and UV shielding properties

Lignin-based microcapsules are extremely attractive for their biodegradability and photolysis resistance. However, the water-soluble all-lignin shells were unsatisfactory in terms of rainfall and foliar retention, and lacked the test of agricultural production practices. Herein, a novel microcapsule based on a flexible skeleton formed by interfacial polymerization and absorbed with lignin particles (LPMCs) was prepared in this study. Further analysis demonstrated that the shell was formed by cross-linking the two materials in layers and showed excellent flexibility and photolysis resistance. The pesticide loaded LPMCs showed about 98.68 % and 73.00 % improvement in scour resistance and photolysis resistance, respectively, as compared to the bare active ingredient. The foliar retention performance of LPMCs was tested in peanut plantations during the rainy season. LPMCs loaded with pyraclostrobin (Pyr) and tebuconazole (Teb) exhibited the best foliar disease control and optimum plant architecture, resulting in an increase in yield of about 5.36 %. LPMCs have a promising application prospect in the efficient pesticide utilization, by controlling its deformation, adhesion and release, an effective strategy for controlling diseases and managing plant growth was developed.

Pesticide Nanoformulations Based on Sunlight-Activated Controlled Release of Abamectin.

A controlled release system that enables the sunlight-triggered release of a model agrochemical, abamectin (abm), is presented. The release system consists of polydopamine functionalized halloysite nanotubes (HNT-PDA) utilized as photothermal nanocarriers to encapsulate 25 wt % abm and 37 wt % lauric acid (LA), a phase change material, that acts as a heat-activable gatekeeper stopping or facilitating the abm release. When exposed to sunlight for 20 min at 1 and 3 sun light density, the temperature of the photothermal nanocarriers reaches 51 and 122 °C, respectively, which triggers the melting of LA and the consequent release of abm from the nanocarriers. Abm was shown to be released gradually over a period of 10 days when nanohybrids were exposed to sunlight for 6 h per day and to remain stable and kill Myzus persicae (Sulzer) (Hemiptera: Aphididae), green peach aphids, at a mortality rate of over 70% for at least 10 days. Aqueous dispersions of the LA/abm@HNT-PDA nanohybrids were studied in terms of their potential as aqueous sprayable pesticide nanoformulations and presented over 30% suspensibility, 36 mg/cm2 foliar retention, strong rainwater resistance, and a 50% mortality rate for M. persicae at a concentration of 9 mg/mL. The proposed sunlight-activated controlled release system based on photothermal, LA-functionalized HNT-PDA nanocarriers holds great potential as controlled release pesticide nanoformulations.

Near-infrared-responsive CuS@Cu-MOF nanocomposite with high foliar retention and extended persistence for controlling strawberry anthracnose

Strawberry anthracnose (Colletotrichum gloeosporioides) exhibits a high pathogenicity, capable of directly infecting leaves through natural openings, resulting in devastating impacts on strawberries. Here, nanocomposite (CuS@Cu-MOF) was prepared with a high photothermal conversion efficiency of 35.3% and a strong response to near-infrared light (NIR) by locally growing CuS nanoparticles on the surface of a copper-based metal-organic framework (Cu-MOF) through in situ sulfurization. The porosity of Cu-MOF facilitated efficient encapsulation of the pesticide difenoconazole within CuS@Cu-MOF (DIF/CuS@Cu-MOF), achieving a loading potential of 19.18 ± 1.07%. Under NIR light irradiation, DIF/CuS@Cu-MOF showed an explosive release of DIF, which was 2.7 times higher than that under dark conditions. DIF/CuS@Cu-MOF exhibited a 43.9% increase in efficacy against C. gloeosporioides compared to difenoconazole microemulsion (DIF ME), demonstrating prolonged effectiveness. The EC50 values for DIF and DIF/CuS@Cu-MOF were 0.219 and 0.189 μg/mL, respectively. Confocal laser scanning microscopy demonstrated that the fluorescently labeled CuS@Cu-MOF acted as a penetrative carrier for the uptake of hyphae. Furthermore, DIF/CuS@Cu-MOF exhibited more substantial resistance to rainwater wash-off than DIF ME, with retention levels on the surfaces of cucumber leaves (hydrophilicity) and peanut leaves (hydrophobicity) increasing by 36.5-fold and 9.4-fold, respectively. These findings underscore the potential of nanocomposite to enhance pesticide utilization efficiency and leaf retention.

Pectin-Coated Iron-Based Metal-Organic Framework Nanoparticles for Enhanced Foliar Adhesion and Targeted Delivery of Fungicides.

Conventional agrochemicals are underutilized due to their large particle sizes, poor foliar retention rates, and difficult translocation in plants, and the development of functional nanodelivery carriers with high adhesion to the plant body surface and efficient uptake and translocation in plants remains challenging. In this study, a nanodelivery system based on a pectin-encapsulated iron-based MOF (TF@Fe-MOF-PT NPs) was constructed to enhance the utilization of thifluzamide (TF) in rice plants by taking advantage of the pectin affinity for plant cell walls. The prepared TF@Fe-MOF-PT NPs exhibited an average particle size of 126.55 nm, a loading capacity of 27.41%, and excellent dual-stimulus responses to reactive oxygen species and pectinase. Foliar washing experiments showed that the TF@Fe-MOF-PT NPs were efficiently adhered to the surfaces of rice leaves and stems. Confocal laser scanning microscopy showed that fluorescently labeled TF@Fe-MOF-PT NPs were bidirectionally delivered through vascular bundles in rice plants. The in vitro bactericidal activity of the TF@Fe-MOF-PT NPs showed better inhibitory activity than that of a TF suspension (TF SC), with an EC50 of 0.021 mg/L. A greenhouse test showed that the TF@Fe-MOF-PT NPs were more effective than TF SC at 7 and 14 d, with control effects of 85.88 and 78.59%, respectively. It also reduced the inhibition of seed stem length and root length by TF SC and promoted seedling growth. These results demonstrated that TF@Fe-MOF-PT NPs can be used as a pesticide nanodelivery system for efficient delivery and intelligent release in plants and applied for sustainable control of pests and diseases.

First Report of Foliar Nematode (Aphelenchoides pseudobesseyi) on Soybean in Colombia

Soybean (Glycine max L.) is produced in over 70,000 ha in the Altillanura Region, eastern Colombia (Agronet 2023). From 2018 to 2020, foliar symptoms like green stem and foliar retention of soybean, which in Brazil can cause up to 100% soybean yield losses (Meyer et al. 2017), were observed in soybean fields in Colombia. During 2020, samples from symptomatic plants in reproductive stages (R1-R8) were collected from different commercial soybean fields in the Altillanura Region. Over 200 samples were processed, using an incubation method described in Coyne et al. (2014). Nematodes were recovered from photosynthetic leaf tissues and enlarged nodes/buds with population densities ranging from 13 to 132 and 36 to 936 nematodes/10g, respectively. Adult females were morphologically and molecularly characterized as Aphelenchoides pseudobesseyi (Oliveira et al. 2019; Subbotin et al. 2020). Female body length (n = 20) ranged from 653.3 to 806.3 μm (mean = 723 μm ± 52.7), stylet length from 11.0 to 12.3 μm (11.8 μm ± 0.3), body diameter from 14.8 to 17.9 μm (16.3 μm ± 1.1), post-uterine sac length from 38.7 to 51.9 μm (44.6 μm ± 5.1), vulva to anus from 145.5 to 223.2 μm (172.2 μm ± 22.4), and 26% of the vulva-anus distance. Genomic DNA was extracted (QIAGEN DNeasy® Blood & Tissue kit) from a pool of nematodes. The D2A/D3B (Tenente et al. 2004) primers were used to amplify and sequence the D2/D3 expansion region of the 28S rRNA gene. PCR product (~759 bp) was purified, sequenced, deposited in GenBank (OQ930285), and compared to previously deposited sequences (e.g., KX356756, KY510840, KY510839, KY510841, KT692694, KY510842, MH187565) by means of the BLAST algorithm. Similarly, 988F and 18SR-Burs (De Jesus et al. 2016) primers were used to amplify and sequence the near full-length 18S RNA gene (SSU). PCR product was purified, sequenced, deposited in GenBank (OQ954344), and compared to previously deposited sequences (e.g., KT454962, KT943534, KT943535, KY510835, KY510836, KY510837, KY510838, MH187565). Phylogenetic Bayesian analysis (Ronquist et al. 2012) of the of the D2/D3 and 18S regions placed this nematode from Colombia in the A. pseudobesseyi clade (PP = 100). To fulfill a modified Koch’s postulates, the A. pseudobesseyi population described above was used in a greenhouse assay. In total, 120 soybean plants (cv. Flor Blanca) were infected with 200 A. pseudobesseyi (females + males)/plant. Briefly, at cotyledon stage (VC), 50 µl aliquot containing 50 A. pseudobesseyi was delivered onto each cotyledon and unifoliolate leaves (200 nematodes/plant). Sterile water was delivered to 80 plants which served as control. Plants were kept in the greenhouse at approximately 25°C and covered with clear plastic bag for 72 h to maintain over 90% relative humidity. After 15, 30, 45, and 60 days, soybean plants (n = 20) were processed, A. pseudobesseyi quantified, and the average reproduction factor (final population/initial population) was 0.1, 2.9, 14.0, and 1.8, respectively. Infected plants showed symptoms of blistering leaves with malformation (midrib vein twist), and A. pseudobesseyi was not observed in control plants. To our knowledge, this is the first report of A. pseudobesseyi parasitizing soybean buds and leaves in Colombia. Soybean is an important commodity for the Altillanura Region, and it is important to monitor the risk posed by this nematode. Furthermore, a better understanding of the nematode-host interaction and epidemiology in Colombia soybean producing regions is needed.

Functional, eco-friendly, and starch-based nanocarriers with sustained release of carvacrol for persistent control of tomato gray mold

Carvacrol (Car) is a promising botanical fungicide. However, the volatile and easily oxidizable characterization of Car hinders its practical application. Herein, an eco-friendly, starch-based nanopesticide (Car@ACS) was successfully constructed by encapsulating of Car within acetylated corn starch, enabling sustained release to prolong its efficacy. In vitro release experiments showed that the release of Car from commercial carvacrol soluble concentrate (Car SL) was 98.4% within 4 h, while that of Car@ACS released 36% within 4 h and 79% within 48 h, demonstrating the endowed sustained release property of the starch nanoparticles. Meanwhile, in vitro antimicrobial activity experiments revealed the fungicidal ability of the prepared Car@ACS and carvacrol technical (Car Tech) with the same concentration of active ingredient to be comparable Botrytis cinerea. In the 7-day pot experiment, the efficacy of the Car@ACS group (56.9%) against B. cinerea was significantly greater than that of the Car SL group (33.3%). In addition, the Car@ACS formulation improved the foliar retention of Car compared to Car SL in hydrophilic cucumber and hydrophobic peanut leaves. Finally, biosafety tests indicated that Car@ACS did not significantly affect the germination or growth of tomato seedlings. Therefore, the advantages of long-lasting disease control properties, improved foliar retention and eco-friendliness indicate that Car@ACS has significant potential to facilitate the application of volatile botanical fungicides.

An emergent plant‐parasitic nematode in Brazil: Aphelenchoides besseyi. Current status and research perspectives

AbstractAphelenchoides besseyi is an emerging and yet overlooked plant parasite of many economically important crops, including cotton, soybean and common bean. It presents an economic risk to these crops in several countries, notably in Brazil. Although first reported infecting strawberries in the United States as early as 1942, it was only identified to be the causal agent of green stem and foliar retention (GSFR) disease in Brazil in 2017. Currently, there are no chemical nematicides registered in Brazil against A. besseyi, and no known sources of genetic resistance. Here, we review the biology of A. besseyi, its spread across Brazil, its relevance to the country's current and future agriculture and the limited control measures. We describe control measures that have been successfully used to manage infestations of other plant‐parasitic nematodes and could potentially be extended to use in the control of A. besseyi. We also review and discuss potential future control measures, such as RNA interference and genome editing, for the development of crops with enhanced resistance to A. besseyi.

Backyard aerosol pollution monitors: foliar surfaces, dust enrichment, and factors influencing foliar retention.

Air pollution is one of the leading causes of death from noncommunicable diseases globally, and in Arizona, both mining activities and abandoned agriculture can generate erodible dust. This dust is transported via wind and can carry high amounts of toxic pollutants. Industry-adjacent communities, or "fenceline communities," are generally closer to the pollution sources and are disproportionally impacted by pollution, or in this case, dust. The dust transported from the mine settles into nearby rivers, gardens, and homes, and increases the concentrations of elements beyond their naturally occurring amounts (i.e., enriched). This study was built upon previous community science work in which plant leaves were observed to collect similar concentrations to an accepted dust collection method and illustrated promise for their use as low-cost air quality monitors in these communities. This work investigated the concentration of Na, Mg, Al, K, Ca, Mn, Co, Cu, Zn, Mo, and Ba in dust from the leaves of community-collected backyard and garden plants (foliar dust), as well as if certain variables affected collection efficacy. This assessment evaluated (1) foliar concentration versus surface area for 11 elements, (2) enrichment factor (EF) values and ratios, (3) comparisons of foliar, garden, and yard samples to US Geological Survey data, and (4) what variable significantly affected dust collection efficacy. The EF results indicate that many of the samples were enriched (anthropogenically contaminated) and that the foliar samples were generally more contaminated than the yard and garden soil samples. Leaf surface area was the most influential factor for leaf collection efficiency (p < 0.05) compared to plant family or sampling location. Further studies are needed that standardize the plant species and age and include multiple replicates of the same plant species across partnering communities. This study has demonstrated that foliar dust is enriched in the participating partnering communities and that plant leaf samples can serve as backyard aerosol pollution monitors. Therefore, foliar dust is a viable indicator of outdoor settled dust and aerosol contamination and this is an adoptable monitoring technique for "fenceline communities."

Molecular selection and environmental evaluation of eco-friendly surfactants to efficiently reduce pesticide pollution

Surfactants are widely used in industrial and agricultural production, especially as agrochemicals. However, the improvement of pesticide utilization by surfactants as the synergist should be achieved without adverse effects on crops, non-target organisms and related ecological environment, which is a lack of attention. Herein, the influence of the nonionic surfactant Triton X (TX) series with different hydrophilic chain lengths on the “Pesticide-Crop-Ecology” system was systematically studied. The impact behavior of TX droplets on the scallion leaf surface was predicted first by molecular dynamics (MD) simulation. Then the impact behavior, adhesion properties and foliar retention of TX droplets on the scallion leaf were investigated by physical experiments. The results showed that the TX-102 structure could increase leaf retention of pyraclostrobin (PYR) by 15.66% due to its fast molecular migration rate, strong adhesion and appropriate wettability with leaves. Furthermore, the environmental effect of the selected TX-102 was fully evaluated, and it was found that TX-102 was relatively safe for both Vicia faba cells and human 293t cells, although it slightly promoted the effect of PYR on cell apoptosis. Importantly, TX-102 has a potential repair effect on the damage to dominant soil bacteria caused by PYR. This study provides a new strategy for the development of efficient and environment-friendly pesticide synergists and sustainable agricultural development.

Influence of foliar traits, watershed physiography, and nutrient subsidies on stream water quality in the upper midwestern United States

The relationship between nutrient cycling and water quality in mixed-use ecosystems is driven by interactions among biotic and abiotic processes. However, the underlying processes cannot always be directly observed or modeled at broad spatial scales. Numerous empirical studies have employed land use patterns, variations in watershed physiography or disturbance regimes to characterize nutrient export from mixed-use watersheds, but simultaneously disentangling the effects of such factors remains challenging and few models directly incorporate vegetation biochemistry. Here we use structural equation models (SEMs) to assess the relative influence of foliar chemical traits (derived from imaging spectroscopy), watershed physiography, and human land use on the water quality (summer baseflow nitrate-N and soluble reactive phosphorus concentration) in watersheds across the Upper Midwestern United States. We use an SEM to link water quality (stream nitrate-nitrogen and dissolved phosphorus) to foliar retention (AVIRIS-Classic derived foliar traits related to recalcitrance), watershed retention (wetland proportion, MODIS Tasseled Cap Wetness), runoff (agricultural and urban land use), and watershed leakiness (AVIRIS-Classic foliar nitrogen, nitrogen deposition). The SEMs confirmed that variables associated with foliar retention derived from imaging spectroscopy are negatively related to watershed leakiness (standardized path coefficient = −0.892) and positively to watershed retention (standardized path coefficient = 0.705), with features related to watershed retention and runoff exerting the strongest controls on water quality (standardized path coefficients of −0.270 and 0.331 respectively). Comparing forested and agricultural watersheds, we found significantly increased importance of foliar retention to watershed leakiness in forests compared to agriculture (standardized coefficients of −1.004 and −0.764 respectively), with measures of watershed retention more important to runoff and water quality in agricultural watersheds. The results illustrate the capacity of imaging spectroscopy to provide measures of foliar traits that influence nutrient cycling in watersheds. Ultimately, the results may help focus development and restoration policies towards building more resilient landscapes that take into consideration associations among functional traits of vegetation, physiography and climate.

High foliar retention tannic acid/Fe3+ functionalized Ti-pillared montmorillonite pesticide formulation with pH-responsibility and high UV stability

The large losses and UV-light instability of traditional pesticide formulations during spraying lead to low drug utilization and a threat to the environment and human health. In this work, a tannic acid and iron ion functionalized titanium dioxide pillared montmorillonite drug sustained-release system was successfully prepared. Pillared montmorillonite showed good foliar retention after tannin modification to prevent the loss of the drug during spraying. Under the irradiation of UV light, the shielding and absorption of UV light by the montmorillonite sheet, TiO2 and tannic acid coating greatly enhanced UV stability of the avermectin (AVM). In addition, AVM@Fe-TA-TiPMt also showed pH response release due to the ion exchange and disintegration of the coating. With the disintegration of tannic acid coating and the release of tannic acid molecules, AVM was rapidly released below pH 7. AVM@Fe-TA-TiPMt exhibited enhanced insecticidal effect due to the excellent foliar retention effect and high drug release. The tannic acid-functionalized sustained-release system has achieved high foliar retention, UV stability and pH-responsive release, which is conducive to the efficient utilization of pesticides and provides valuable information for the development of clay-based pesticide formulations in the future.

Enhanced detoxification via Cyt-P450 governs cross-tolerance to ALS-inhibiting herbicides in weed species of Centaurea

Centaurea is a genus of winter weeds with a similar life cycle and competitive traits, which occurs in small-grains production fields in the central-southern of the Iberian Peninsula. However, most of herbicides recommended for weed management in wheat show poor control of Centaurea species. This study summarizes the biology, herbicide tolerance to acetolactate synthase (ALS) inhibitors, and recommended chemical alternatives for the control of Centaurea species. Four species (C. cyanus L., C. diluta Aiton, C. melitensis L. and C. pullata L. subsp. baetica Talavera), taxonomically characterized, were found as the main important broadleaf weeds in small-grains production fields of the Iberian Peninsula. These species showed innate tolerance to tribenuron-methyl (TM), showing LD50 values (mortality of 50% of a population) higher than the field dose of TM (20 g ai ha−1). The order of tolerance was C. diluta (LD50 = 702 g ha−1) ≫ C. pullata (LD50 = 180 g ha−1) ≫ C. cyanus (LD50 = 65 g ha−1) > C. melitensis (LD50 = 32 g ha−1). Centaurea cyanus and C. melitensis presented higher foliar retention (150–180 μL herbicide solution), absorption (14–28%) and subsequent translocation (7–12%) of TM with respect to the other two species. Centaurea spp. plants were able to metabolize 14C-TM into non-toxic forms (hydroxylated OH-metsulfuron-methyl and conjugated-metsulfuron-methyl), with cytochrome P450 (Cyt-P450) monooxygenases being responsible for herbicide detoxification. Centaurea cyanus and C. mellitensis metabolized up to 25% of TM, while C. diluta and C. pullata metabolized more than 50% of the herbicide. Centaurea species showed 80–100% survival when treated with of florasulam, imazamox and/or metsulfuron-methyl, i.e., these weeds present cross-tolerance to ALS inhibitors. In contrast, auxin mimics herbicides (2,4-D, clopyralid, dicamba, fluroxypir and MCPA) efficiently controlled the four Centaurea species. In addition, the mixture of ALS-inhibitors and auxin mimics also proved to be an interesting alternative for the control of Centaurea. These results show that plants of the genus Centaurea found in the winter cereal fields of the Iberian Peninsula have an innate tolerance to TM and cross-resistance to other ALS-inhibiting herbicides, governed by reduced absorption and translocation, but mainly by the metabolization of the herbicide via Cyt-P450.

Host-parasite relationship between Aphelenchoides besseyi and soybean

Summary Aphelenchoides besseyi is a concern to Brazilian agriculture, since the losses caused by the green stem and foliar retention syndrome in soybean, especially in hot and humid climates, could reach high levels. However, limited information is available regarding the host-parasite relationship. The objective of this study was to evaluate the capacity of A. besseyi to penetrate soybean roots and its movement in soybean tissues until reaching the top parts. Plants inoculated with 1000 A. besseyi were evaluated for root penetration from 1-28 days after inoculation (DAI), and post-penetration and movement inside tissues by staining them with acid fuchsin. Plant development, chronology of the symptoms and the number of pods were also evaluated at 60 DAI. Aphelenchoides besseyi was found in the cortex and xylem vessels of roots from 1 DAI. During the experimental period, the number of nematodes from roots to shoots increased more than 123, 330 and 430%, respectively, for roots, stems + petioles + inflorescences, and leaves, demonstrating the ascendent movement of A. besseyi. Necrotic lesions in young leaves and apical tissues were observed from 8 DAI; the typical symptom of ‘amachamiento’ was observed from 10 DAI, with enlargement of nodes and lesions in inflorescences and, at 30 DAI, stunted plants were detected. At 60 DAI, inoculated plants had lower numbers of pods and exhibited severe symptoms including abortion of flowers and tissue splitting and cortical lesions in a few pods and roots. These observations emphasise the importance of A. besseyi for Brazilian soybean production.

Early Cretaceous Keteleerioxylon Wood in the Songliao Basin, Northeast China, and Its Geographic and Environmental Implications.

The extant Keteleeria is endemic to east and southeast Asia, while Keteleeria-like trees were widely distributed in the northern hemisphere in Earth's history. In this paper, we reported a novel wood fossil of Keteleerioxylon changchunense Shi, Sun, Meng et Yu sp. nov., collected from the middle part of the Yingcheng Formation, Yingcheng Coal Mine, Changchun City, Jilin Province, northeast China. The quantitative growth-ring analyses of K. changchunense indicate that it was evergreen with a leaf longevity of 1-3 years, which is consistent with the foliar retention of extant Keteleeria. Its high ring-markedness index (RMI) indicates that the climate seasonality was pronounced during the Early Albian period in the Songliao Basin, northeast China. The fossil records of Keteleeria and closely related taxa indicate that this group might have originated from high latitudes in the northern hemisphere, then spread and migrated southward during the Late Jurassic and Cretaceous periods, gradually decreased in the Cenozoic period, and so far only survives in east and southeast Asia.

Lignin-based non-crosslinked nanocarriers: A promising delivery system of pesticide for development of sustainable agriculture

Lignin sulfonate (LS), a waste material from the paper pulping, was modified with benzoic anhydride to obtain benzoylated lignin sulfonates of adjustable hydrophilicity (BLS). When BLS was combined with difenoconazole (Di), a broad-spectrum fungicide, lignin-based, non-crosslinked nanoparticles were obtained either by solvent exchange or solvent evaporation. When a mass ratio of 1:5 LS: benzoic anhydride was used, the Di release from Di@BLS5 after 1248 h was ca. 74 %, while a commercial difenoconazole microemulsion (Di ME) reached 100 % already after 96 h, proving the sustained release from the lignin nanocarriers. The formulation of Di in lignin-based nanocarriers also improved the UV stability and the foliar retention of Di compared to the commercial formulation of the fungicide. Bioactivity assay showed that Di@BLS5 exhibited high activities and duration against strawberry anthracnose (Colletotrichum gloeosporioides). Overall, the construction of fungicide delivery nano-platform using BLS via a simple non-crosslinked approach is a novel and promising way to develop new formulations for nanopesticide and the development of sustainable agriculture.

Experimental modelling for phenotyping soybean host reaction to Aphelenchoides besseyi

Summary The nematode causing the green stem and foliar retention syndrome of soybean, Aphelenchoides besseyi, is a concern to Brazilian growers, especially in warm and humid climates, where losses can reach 60% of the yields. Management options have not yet been studied properly, but apparently genetic variability is found in soybean genotypes in the resistance to this nematode. However, the correct phenotyping of soybean genotypes is compromised by the scarcity of studies of this pathosystem. Therefore, the objective of this study was to evaluate the inoculum densities of A. besseyi and the plant ages at inoculation to obtain the correct phenotyping of soybean genotypes. Experiments were conducted under glasshouse conditions with the soybean ‘Elite’, using a completely randomised design and a factorial scheme (five nematode population densities: 150, 300, 600, 1200 and 2400 nematodes plant−1, and three plant ages at inoculation: 7, 12 and 17 days after planting). Evaluations were performed 35 days after inoculation, extracting nematodes from soil, roots and shoot parts of plants to obtain the final population of the nematodes of each replicate. The inoculum of 150-300 A. besseyi specimens per plant is the most suitable to assess the reaction of soybean genotypes to this nematode as it resulted in the greatest reproduction factors. Population densities higher than 1500 nematodes per plant could lead to misclassification of the host reaction because of the inconsistent reproduction factors obtained.

RNAi in Piezodorus guildinii (Hemiptera: Pentatomidae): Transcriptome Assembly for the Development of Pest Control Strategies.

Red-banded stink bug Piezodorus guildinii (P. guildinii) has been described as the most damaging stink bug regarding soybean crops, leading to seed injury, low germination percentages, and foliar retention, at low population densities. In recent years, RNA interference (RNAi), a conserved eukaryote silencing mechanism has been explored to develop species-selective pesticides. In this work, we evaluated RNAi in P. guildinii to develop new pest-control strategies. For this, we assembled and annotated a P. guildinii transcriptome from a pool of all developmental stages. Analysis of this transcriptome led to the identification of 56 genes related to the silencing process encompassing siRNA, miRNA, and piRNA pathways. To evaluate the functionality of RNAi machinery, P. guildinii adults were injected with 28 ng/mg of body weight of double stranded RNA (dsRNA) targeting vATPase A. A mortality of 35 and 51.6% was observed after 7 and 14 days, respectively, and a downregulation of vATPase A gene of 84% 72 h post-injection. In addition, Dicer-2 and Argonaute-2 genes, core RNAi proteins, were upregulated 1.8-fold 48 h after injection. These findings showed for the first time that RNAi is functional in P. guildinii and the silencing of essential genes has a significant effect in adult viability. Taken together, the work reported here shows that RNAi could be an interesting approach for the development of red-banded stink bug control strategies.