Wheat Root Protection From Cereal Cyst Nematode (Heterodera avenae) by Fluopyram Seed Treatment.

Cereal cyst nematode (Heterodera avenae), an important plant-parasitic nematode causing yield losses of wheat, has been found in many provinces in China. It is urgent to develop an effective method of protecting wheat from H. avenae damage. Because of its novel mode of action, fluopyram has been registered for controlling root-knot nematodes on cucumber and tomato in China. However, the bioactivity of fluopyram against H. avenae and whether this seed treatment can effectively control H. avenae on wheat remains unknown. In this study, a bioactivity assay revealed that fluopyram increased the mortality of H. avenae second-stage juveniles (J2), with lethal concentrations (LC) required to kill 50% (LC50) and 90% (LC90) of 0.92 mg⋅liter-1 and 2.92 mg⋅liter-1, respectively. Hatching tests showed that the H. avenae egg hatching percent was reduced by 35.2 to 69.2% with fluopyram at rates of 1.6 to 6.4 mg⋅liter-1, and that the egg hatching period was delayed by 3 to 9 days compared with the control. During pot and field trials, fluopyram seed treatment significantly reduced the H. avenae population density and increased wheat yield by 3.0 to 13.7%. Therefore, fluopyram seed treatment is an effective approach for the management of H. avenae on wheat in China.

Assessment of ethylene glycol diacetate as an alternative carrier for use in agrochemical emulsifiable concentrate formulation.

The conventional emulsifiable concentrate (EC) formulation contains a large amount of aromatic solvents, which causes adverse effects to both the environment and human health due to the toxicity of the solvents. Here, we developed a 2.5% lambda-cyhalothrin EC formulation with ethylene glycol diacetate (EGDA) as the solvent, and the developed formulation serves as an environmental-friendly alternative to overcome the adverse effects of aromatic solvents. The physicochemical characterizations, wettability properties, phytotoxicity and bioassays of the EGDA-EC formulation were systematically investigated and compared with that of the EC formulation with xylene as the solvent. The results showed that both EC formulations had excellent emulsion properties and storage stabilities. Additionally, the EGDA-EC formulation possessed a higher flash point (96 °C), indicating safer production, storage and transport. The retentions of the EGDA-EC sample on leaves were 1.22-1.46-fold higher than that of the xylene-EC sample, and the EGDA-EC also exhibited lower surface tensions and contact angles, which would benefit decreasing drift-off and improving utilization. Furthermore, the bioassays demonstrated that the EGDA-EC formulation had lower acute toxicity to aquatic organisms and higher control efficacy to target insects compared with the xylene-EC formulation. Therefore, EGDA is a promising carrier for oil-soluble agrochemicals to improve their application performance and reduce their adverse effects.

Effects of the plant volatile trans­2-hexenal on the dispersal ability, nutrient metabolism and enzymatic activities of Bursaphelenchus xylophilus.

Bursaphelenchus xylophilus causes pine wilt disease (PWD), which severely damages pine species. The plant volatile trans­2-hexenal has strong activity against nematodes, although the precise mechanism of this inhibitory action remains unclear. In this paper, the fumigant effects of the LC10 and LC30 of trans­2-hexenal on B. xylophilus were demonstrated. The trans­2-hexenal treatments significantly inhibited the dispersal ability of nematodes. The results also indicated that trans­2-hexenal affects the metabolism of nutrients and the activity of digestive enzymes. Among detoxifying enzymes, after treatment with trans­2-hexenal, glutathione S-transferase activity increased significantly and general esterase activity decreased significantly. Based on these results, trans­2-hexenal disturbs the normal physiological and biochemical activities of this nematode. These results provide valuable insight into the nematicidal mechanisms of trans­2-hexenal.

Spontaneously Formed Ratio-Tunable Micro- and Nano-Capsule Coexist System for Precision and on-Demand Fungicide Delivery in Crop Leave.

Multiscale particle size functional pesticide carriers can provide more efficient protection for plants, but this protection is difficult to achieve via single-scale formulation technology. This study presents a novel one-step method for the preparation of lignin-based micro/nanocapsules with controllable proportions within a unified system. This strategy enables the adjustment of the proportion of nanocapsules to between 18.81% and 85.21%. The microcapsules (MCs) vary in diameter from 2 to 3 µm, whereas the nanocapsules (NCs) span from 160 to 220 nm, with an encapsulation efficiency exceeding 90%. An increased proportion of NCs in the system leads to faster release, heightened sensitivity to UV light, and enhanced penetration into the leaves. During Phytophthora capsici (P. capsici) infection, the NCs in the leaves interact with the defensive enzymes of the plant to quickly respond. Moreover, an optimal balance of MCs and NCs is key to effective fungicide use, not just a higher concentration of NCs. A 65:35 ratio of NCs to MCs ensures effective inhibition of P. capsici outside leaves and a rapid response to leaf invasion. This study enhances fungicide efficiency and advances the development of nanoresponsive fungicides to promote sustainable agricultural practices.

The effect of lambda-cyhalothrin nanocapsules on the gut microbial communities and immune response of the bee elucidates the potential environmental impact of emerging nanopesticides.

Emerging nanopesticides are gradually gaining widespread application in agriculture due to their excellent properties, but their potential risks to pollinating insects are not fully understood. In this study, lambda-cyhalothrin nanocapsules (LC-NCs) were constructed by electrostatic self-assembly method with iron mineralization optimization, and their effects on bee gut microbial communities and host immune-related factors were investigated. Microbiome sequencing revealed that LC-NCs increase the diversity of gut microbial communities and reduce the complexity of network features, disrupting the overall structure of the microbial communities. In addition, LC-NCs also had systemic effects on the immune response of bees, including increased activity of SOD and CAT enzymes and expression of their genes, as well as downregulation of Defensin1. Furthermore, we noticed that the immune system of the host was activated simultaneously with a rise in the abundance of beneficial bacteria in the gut. Our research emphasizes the importance of both the host and gut microbiota of holobiont in revealing the potential risks of LC-NCs to environmental indicators of honey bees, and provides references for exploring the interactions between host-microbiota systems under exogenous stress. At the same time, we hope that more research can focus on the potential impacts of nanopesticides on the ecological environment.

Sustainable lignin-modified epoxy nanocarriers for enhanced foliar insecticide efficacy and food safety.

Reducing pesticide residues while extending their efficacy period is a critical challenge in the development of controlled-release pesticides. This study focuses on loading avermectin onto lignin-modified epoxy resin nanocarriers via the creation of photostable nanocapsules (NCs) for evaluating their efficacy against Plutella xylostella. This study also assesses the NCs' resistance to water scour on plant leaves by comparing them with traditional preparations. These NCs feature a stable core-shell structure, an encapsulation efficiency of 92.90 % and slow-release properties. Compared to emulsifiable concentrate (EC) and microemulsion (ME) under UV irradiation, the loading of nanocarriers significantly prolonged the degradation time of avermectin by fivefold. The Nano-formula demonstrated enhanced insecticidal activity in comparison to traditional preparations. Field tests revealed that the efficacy of the NCs on Day 7 (92.55 %) and Day 14 (78.54 %) significantly surpassed that of traditional preparations. Additionally, NCs are more readily washed off cabbage leaves by water than EC and ME, aiding in the reduction of pesticide residues. This technology is particularly suitable for leafy vegetable crops in arid regions or greenhouses, enhancing effectiveness period while minimizing pesticide residues. This research offers novel insights and directions for the development of controlled-release pesticides.

A novel approach to managing facility airborne diseases: suppressing air pathogens with smoke aerosols generated from fungicide phase transition.

BACKGROUND: Environmental microorganisms are major contributors to the development and spread of disease. Chemical disinfection can inhibit pathogens and play a preventive role against diseases. In agriculture, prolonging the floating time of chemical pesticides in the air has a positive effect on the control of airborne diseases. However, the interaction of chemical pesticides with airborne pathogens is not yet known. RESULTS: Here, triazole fungicide was transformed into stable smoke aerosols in order to assess the feasibility of employing phase transition release pesticides for air disinfection. The phase transition had a minimal impact on hexaconazole (Hexa) and myclobutanil (Mycl), with their smoke formation rates remaining consistently >90%. In microscopic morphology, triadimenol (Tria) and epoxiconazole (Epox) are solid, and tebuconazole (Tebu), Hexa, Mycl and difenoconazole (Dife) are liquid. Liquid smoke has advantages over solid smoke in the inhibition of environmental pathogens. The floatability and spatial distribution of fungicide aerosol were optimized by the combination of smoke particles with different properties, so that the fungicide aerosol could meet the conditions of practical application. In practical applications, smoke exhibits a gentler deposition process at the target interface compared to spray, along with a more homogeneous distribution of fungicides. Moreover, fungicide smoke demonstrates superior control efficacy and leaves behind lower residual amounts on fruit. CONCLUSION: In conclusion, the implementation of fungicide phase transition as a smoke aerosol offers a viable approach to effectively suppress pathogen aerosols and enhance the control of airborne diseases. © 2024 Society of Chemical Industry.

Effects of abamectin nanocapsules on bees through host physiology, immune function, and gut microbiome.

Pesticide usage is a common practice to increase crop yields. Nevertheless, the existence of pesticide residues in the surrounding environment presents a significant hazard to pollinators, specifically the potential undisclosed dangers related to emerging nanopesticides. This study examines the impact of abamectin nanocapsules (AbaNCs), created through electrostatic self-assembly, as an insecticide on honey bees. It was determined that AbaNCs upregulated detoxification genes, including CYP450, as well as antioxidant and immune genes in honey bees. Furthermore, AbaNCs affected the activity of crucial enzymes such as superoxide dismutase (SOD). Although no apparent damage was observed in bee gut tissue, AbaNCs significantly decreased digestive enzyme activity. Microbiome sequencing revealed that AbaNCs disrupted gut microbiome, resulting in a reduction of beneficial bacteria such as Bifidobacterium and Lactobacillus. Additionally, these changes in the gut microbiome were associated with decreased activity of digestive enzymes, including lipase. This study enhances our understanding of the impact of nanopesticides on pollinating insects. Through the revelation of the consequences arising from the utilization of abamectin nanocapsules, we have identified potential stress factors faced by these pollinators, enabling the implementation of improved protective measures.

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.

Interfacial Polymerization Depth Mediated by the Shuttle Effect Regulating the Application Performance of Pesticide-Loaded Microcapsules.

The highly water-soluble nematicide fosthiazate is anticipated to undergo microencapsulation in order to enhance its retention around plant roots and mitigate leaching into groundwater. However, the underlying mechanism governing the influence of hydrophilicity of the microcapsule (MC) core on the evolution of the microcapsule shell remains unclear, posing challenges for encapsulating water-soluble core materials. This study elucidates the microlevel formation mechanism of microcapsules by investigating the impact of interfacial mass transfer on shell formation and proposes a method for regulating the structure of shells. The study reveals that enhancing the hydrophilicity of the core enhances the shuttle effect between the oil and aqueous phase, expands the region of polymerization reactions, and forms a loose and thick shell. The thickness of the microcapsule shell prepared using solvent oil 150# (MCs-SOL) measures only 264 nm, while that of the microcapsules prepared using propylene glycol diacetate and solvent oil 150# at a ratio of 2:1 (MCs-P2S1) is 5.2 times greater. The enhanced compactness of the shell reduced the release rate of microcapsules and the leaching distance of fosthiazate in soil, thereby mitigating the risk of leaching loss and facilitating the distribution of active ingredients within crop roots. The MCs-SOL had a limited leaching distance measurement of 8 cm and exhibited a satisfactory efficacy of 87.3% in controlling root galling nematodes. The thickness and compactness of the MCs shell can be regulated by manipulating the interfacial shuttle effect, providing a promising approach to enhancing utilization efficiency while mitigating potential environmental risks.

One-pot construction of epoxy resin nanocarrier delivering abamectin and its efficacy on plant root-knot nematodes.

BACKGROUND: The complex preparation process and storage instability of nanoformulations hinders their development and commercialization. In this study, nanocapsules loaded with abamectin were prepared by interfacial polymerization at room temperature and ordinary pressure using the monomers of epoxy resin (ER) and diamine. The potential mechanisms of primary amine and tertiary amine in influencing the shell strength of the nanocapsules and the dynamic stability of abamectin nanocapsules (Aba@ER) in the suspension system were systematically researched. RESULTS: The tertiary amine catalyzed the self-polymerization of epoxy resin into linear macromolecules with unstable structures. The structural stability of the diamine curing agent with a primary amine group played a key role in enhancing the structural stability of the polymers. The intramolecular structure of the nanocapsule shell formed by isophorondiamine (IPDA) crosslinked epoxy resin has multiple spatial conformations and a rigid saturated six-membered ring. Its structure was stable, and the shell strength was strong. The formulation had stable dynamic changes during storage and maintained excellent biological activity. Compared with emulsifiable concentrate (EC), Aba@ER/IPDA had superior biological activity, and the field efficacy on tomato root-knot nematode was enhanced by approximately 31.28% at 150 days after transplanting. CONCLUSION: Aba@ER/IPDA, which has excellent storage stability and simple preparation technology, can provide a nanoplatform with industrial prospects for efficient pesticide delivery. © 2023 Society of Chemical Industry.

The effect of abamectin application in combination with agronomic measures on the control efficacy of cucumber root-knot nematodes and the cucumber yield.

BACKGROUND: As a registered non-fumigant nematicide, abamectin has been widely used as a soil treatment against many cash crop nematode diseases. In a previous study, we found that soil adsorption hindered the stable performance of abamectin against root-knot nematodes in the field. RESULTS: In this study, an efficient and labor-saving application method of soil blending abamectin combined with rotary tillage, a common agronomic measure, was developed to improve the efficacy of abamectin against root-knot nematode disease. We revealed the role of four parameters in this application method. At an abamectin dose of 750 g a.i. ha-1 , spray water volume of 675 L ha-1 and rotation depth of 20 cm, abamectin was well distributed in the 0-20 cm soil layer at a concentration of 0.41-0.46 mg kg-1 , the efficacy against root-knot nematode disease was 72.12%, and the cucumber yield was 51.93 t ha-1 . At the same dosage, root irrigation and flood irrigation measures resulted in only 29.28% and 33.43% control, with cucumber yields of 42.96 and 44.73 t ha-1 , respectively. CONCLUSION: To control root-knot nematode disease with abamectin, a soil blending application combined with rotary tilling is superior to leaching application combined with the agronomic measure of irrigation. The former application method can improve the dispersion of abamectin in the soil, enhance the efficacy of abamectin against root-knot nematodes and maintain a stable cucumber yield. In addition, the increased labor required for application combined with agronomic measures is negligible and has excellent application prospects. © 2023 Society of Chemical Industry.

Amphiphilicity-Driven Small Alcohols Regulate the Flexibility of Pesticide-Loaded Microcapsules for Better Foliar Adhesion and Utilization.

The foliar loss of pesticides causes serious utilization decline and environmental risk. On the basis of biomimetics, pesticide-loaded microcapsules (MCs) with spontaneous deformation on foliar micro/nanostructures, like the snail suction cup, are prepared by interfacial polymerization. By controlling the usage or types of small alcohols in the MC preparation system, the flexibility of MCs is tunable. Through the investigation of emulsions and MC structures, we discover that the migration and distribution of small alcohols driven by amphiphilicity affect the process of interfacial polymerization between polyethylene glycol and 4,4-methylenediphenyl diisocyanate. By hydrophobic modification of the polymer and competition for oil monomers of small alcohols, the thickness and compactness of shells are reduced, whereas the density of the core is increased. As a result of the regulation in structures, the flexibility of MCs is improved significantly. In particularly, the MCs-N-pentanol (0.1 mol kg-1) with the best flexibility show strong scouring resistance on varied foliar structures, sustained release property on the air/solid interface, and persistent control effect against foliar diseases. The pesticide-loaded soft MCs provide an effective way to improve pesticide foliar utilization.

One-Step Construct Responsive Lignin/Polysaccharide/Fe Nano Loading System Driven by Digestive Enzymes of Lepidopteran for Precise Delivery of Pesticides.

A strategy that relies on the differences in feeding behavior between pests and natural enemies to deliver insecticides precisely was proposed. After proving that the digestive enzymes in Lepidopteran pests can act as triggers for lignin-based controlled-release carriers, a novel multiple-enzyme-responsive lignin/polysaccharide/Fe nanocarrier was constructed by combining the electrostatic self-assembly and chelation and loaded with lambda-cyhalothrin (LC) to form a nanocapsule suspension loading system. The nanocapsules were LC@sodium lignosulfonate/chitosan/Fe (LC@SL/CS/Fe) and LC@sodium lignosulfonate/alkyl polyglycoside quaternary ammonium salt/Fe (LC@SL/APQAS/Fe). LC@SL/APQAS/Fe was more stable than LC@SL/CS/Fe because it adsorbs more Fe3+, and the half-lives of LC in LC@SL/APQAS/Fe under UV irradiation were prolonged at 4.02- and 6.03-folds than those of LC@SL/CS/Fe and LC emulsifiable concentrate (LC EC), respectively. Both LC@SL/APQAS/Fe and LC@SL/CS/Fe have responsive release functions to laccase and cellulase, and the release rate of the former was slower. The insecticidal activity of LC@SL/APQAS/Fe against Agrotis ipsilonis was similar to those of LC@SL/CS/Fe and LC EC, while the toxicity of LC@SL/APQAS/Fe to the natural enemy was 2-3 times less than those of LC@SL/CS/Fe and LC EC. Meanwhile, the organic solvent component in the nanocapsule suspension was 94% less than that in the EC preparation. Therefore, the nano loading system based on SL/APQAS/Fe is a promising nanoplatform with the advantages of high efficiency, low toxicity, and environmental friendliness.

Emamectin benzoate nanogel suspension constructed from poly(vinyl alcohol)-valine derivatives and lignosulfonate enhanced insecticidal efficacy.

To reduce the negative impact of nanopesticide carriers of on the environment, a greener nanodelivery system is necessary. Nanogels are nontoxic and degradable carriers, however, the potential of nanogels for delivering pesticides has not been proven. In this study, poly(vinyl alcohol)-valine, an ecofriendly polymer, was synthesized and used to fabricate emamectin benzoate nanogel suspension (EB NS). The nanoformulation showed favorable stability at low temperature, high temperature or one year storage, and in water with different hardnesses. The retention of the EB NS solution on leaves was higher than that of an EB emulsifiable concentrate (EC) by approximately 9% at a concentration of 10 mg L-1. The half-life of EB nanogels under Ultra Violet irradiation was prolonged by 3.3-fold. Moreover, the bioactivity of the EB NS against Plutella xylostella was higher than that of the EB EC. These advantages resulted in a relatively long duration of pest control. The response of nanogels to laccase, a digestive enzyme in the digestive tract of lepidopteran pests, enables pesticide release on demand. Nanogels have the advantages of being ecofriendly carriers, exhibiting higher utilization, and prolonged pest control periods, and they have a brilliant future in pesticide delivery.

Achieving Win-Win Ecotoxicological Safety and Fungicidal Activity of Pyraclostrobin-Loaded Polyurea Microcapsules by Selecting Proper Polyamines.

The fungicide pyraclostrobin is highly toxic to aquatic organisms. Microencapsulation is an effective way to reduce the exposure of pyraclostrobin to aquatic organisms but it also reduces the contact probability between the fungicide and plant pathogens. Hence, winning a balance between the toxicity and bioactivity of pyraclostrobin is very necessary. In this study, triethylenetetramine (TETA), ethylenediamine (EDA), hexamethylenediamine (HAD), and isophoronediamine (IPDA) were selected as cross-linkers to prepare the pyraclostrobin-loaded polyurea microcapsules (PU-MCs) by interfacial polymerization. TETA formed the shells with the highest degree of cross-linking, the slowest release profile, and the best protection against ultraviolet (UV). In terms of MCs fabricated by diamines, higher leaking, weaker UV resistance of the shells was observed with increasing carbon skeleton. TETA-MCs showed the highest safety to zebrafish (LC50 of 10.086 mg/L), whereas EDA-MCs, HAD-MCs, and IPDA-MCs were 5.342, 3.967, and 0.767 mg/L, respectively. TETA-MCs had the best long-term disease management, while the control efficacies of other MCs were higher at the early stage of disease development. Overall, a balance between the aquatic toxicities and fungicidal activities of pyraclostrobin-loaded PU-MCs could be reached through a simple selection of polyamines in the fabrication.

Using a reactive emulsifier to construct simple and convenient nanocapsules loaded with lambda-cyhalothrin to achieve efficient foliar delivery and insecticidal synergies.

Nanocapsules are a promising controlled release formulation for foliar pest control. However, the complicated process and high cost limit widespread use in agriculture, so a simpler and more convenient preparation system is urgently needed. Meanwhile, under complex field conditions, the advantageous mechanism of the nanosize effect and sustained release have no quantitative and detailed study. In this study, a reactive emulsifier (OP-10) is used to participate in the interfacial polymerization of the nanoemulsion, and polymer nanocapsules loaded with lambda-cyhalothrin (NCS@LC) are quickly and easily prepared to study the efficacy and synergistic mechanism of foliar pest control. As a result, the nanocapsule is about 150 nm with a stable core-shell structure. The nanoscale state increases the distribution and adhesion of the particles on the leaf surface, which increases the contact efficiency of pesticides under the different physiological stages and behavioral activities of the target organism. The shell structure provides sustained release characteristics and increases the UV resistance by about 2.5 times for pesticides. Compared with microcapsules loaded with lambda-cyhalothrin (CS@LC), NCS@LC not only shows rapid and synergistic insecticidal efficacy but also provides sustained insecticidal efficacy. The mortality of NCS is 3.4 times that of the nanosized emulsion in water (NEW) at the lowest concentration (0.5 mg L-1), and the control efficacy remained 77.3% after 7 days. Compared with NEW, NCS@LC provides excellent field efficacy, while LC50 for zebrafish is only 0.68 times without increasing the aquatic toxicity risk.

Self-Assembled Degradable Nanogels Provide Foliar Affinity and Pinning for Pesticide Delivery by Flexibility and Adhesiveness Adjustment.

At present, it is highly important to develop a simple and compatible nano delivery system for pesticides for foliar application, which can improve their insecticidal efficacy and resistance to adverse climates while reducing the environmental risks. Polyethylene glycol and 4,4-methylenediphenyl diisocyanate are used as hydrophilic soft and hydrophobic hard segments, respectively, for polymer self-assembly and polyurethane gelation in a nanoreactor. The nanocarrier synthesis and the pesticide loading are realized by a one-step integration procedure and suited well for hydrophobic active compounds. Modifying the molecular structure of the soft segment can adjust the flexibility of the nanocarriers and result in viscosity and deformation characteristics. After foliar spray application, the foliar flattening state of the nanogels increases the foliar protection area by 2.21 times and improves both pesticide exposure area and target contact efficiency. Concurrently, the flexibility and viscosity of the nanogels increase the washing resistance and the retention rate of the pesticide by approximately 80 times under continuous washing. The encapsulation of the nanogels reduces the foliar ultraviolet (UV) degradation and aquatic pesticide exposure, which increase the security of λ-cyhalothrine by 9.33 times. Moreover, the degradability of nanogels is beneficial for pesticide exposure and reducing pollution. This system has simple preparation, good properties, and environmental friendliness, making the nanocarriers promising for delivering pesticides.

Improving the efficacy against crop foliage disease by regulating fungicide adhesion on leaves with soft microcapsules.

BACKGROUND: Increasing pesticide retention on crop leaves is a key approach for guaranteeing efficacy when products are applied to foliage. Evidently, the formulation plays an important role in this process. Microcapsules (MCs) are a promising formulation, but whether and how their adhesion to the leaf surface affects retention and efficacy is not well understood. RESULTS: In this study, we found that the incorporation of polyethylene glycol (PEG) with different molecular weights into the MC shell affects the release profile of MCs and the contact area of these MCs to leaves by changing their softness. The cumulative release rates of pyraclostrobin (Pyr) MCs fabricated with PEG200, PEG400, PEG800 and PEG1500 were 80.61%, 90.98%, 94.07% and 97.40%, respectively. Scanning electron microscopy observations showed that the flexibility of the MCs increased with increasing PEG molecular weight. The median lethal concentration (LC50 ) of the MCs with different PEG to the zebrafish were 12.10, 8.10, 3.90 and 1.46 mg L-1 , respectively, which also indirectly reflected their release rate. Rainwater had less influence on the retention of the MCs prepared with PEG1500 than with the other PEG, which indicates a better adhesion to the target leave surfaces. MCs with the highest residual efficacy had better control efficacy on peanut leaf spot in field trials. CONCLUSION: Overall, adding PEG with an appropriate molecular weight to the MC shell can regulate the structure of the MC shell to improve the affinity between the MCs and leaves, which further improves the utilization of pesticides and reduces the environmental risks of pesticides. © 2021 Society of Chemical Industry.

Lignin-Modified Electronegative Epoxy Resin Nanocarriers Effectively Deliver Pesticides against Plant Root-Knot Nematodes (Meloidogyne incognita).

It is highly desirable to fabricate a pesticide delivery system with excellent permeability to reduce the damage caused by root-knot nematodes in the soil. In this work, a novel electronegative pesticide nanocarrier was established by bonding anionic lignosulfonate with epoxy resin nanocarriers, which were loaded with abamectin (Aba). The results demonstrated that nanoparticles were negatively charged (-38.4 mV) spheres with an average size of 150 nm, and the encapsulation efficiency of nanocarriers for Aba was 93.4%. Polymer nanocarriers could prevent premature release of Aba and protect active ingredients from microbiological degradation. The adsorption strength of the soil to Aba loaded in nanocarriers was reduced by 6 to 10 times, so nanonematicides have remarkable soil mobility. Meanwhile, nanoparticles could easily penetrate the roots and nematodes. The application test confirmed that the control effect of this nanopesticide was 26-40% higher than that of the other agrochemicals. In consideration of its superior bioactivity and utilization rate, this pesticide delivery system has promising potential to control root-knot nematodes and improve the pesticide's utilization efficiency.