Pesticides Research Articles

Antifungal Activity of Difenoconazole-Loaded Microcapsules against Curvularia lunata.

Difenoconazole-loaded (CS-DIF) microcapsules were synthesized by encapsulating difenoconazole into biocompatible chitosan. The physical and chemical properties indicated that the encapsulation and chemical loading rates were 85.58% and 61.98%, respectively. The microcapsules exhibited prominent controlled-release and surface stability performance. The cumulative release rate was only 33.6% in 168 h, and the contact angle decreased by 11.73° at 120 s compared with difenoconazole. The antifungal activity of the CS-DIF microcapsules against Curvularia lunata was confirmed through observations of colony growth, in vitro and in vivo inoculation, mycelium morphology, as well as DNA and protein leakage. The antioxidant enzyme activity of superoxide dismutase, peroxidase, and catalase decreased by 65.1%, 84.9%, and 69.7%, respectively, when Curvularia lunata was treated with 200 μg/mL microcapsules, compared with the control in 24 h. The enzymatic activity of polyphenol oxidase decreased by 323.8%. The reactive oxygen species contents of hydrogen peroxide and superoxide anions increased by 204.6% and 164%, respectively. Additionally, the soluble sugar and soluble protein contents decreased by 65.5% and 69.6%, respectively. These findings provided a novel approach to control the growth of C. lunata efficiently, laying a foundation for reducing the quantity and enhancing the efficiency of chemical pesticides. The CS-DIF microcapsules exhibited a strong inhibitory effect on fungus, effectively preventing and controlling leaf spot disease and showing potential for field applications. This study might be of great significance in ensuring plant protection strategies.

RNA interference-based strategies to control Botrytis cinerea infection in cultivated strawberry

Key messageGene silencing of BcDCL genes improves gray mold disease control in the cultivated strawberry.Gene silencing technology offers new opportunities to develop new formulations or new pathogen-resistant plants for reducing impacts of agricultural systems. Recent studies offered the proof of concept that the symptoms of gray mold can be reduced by downregulating Dicer-like 1 (DCL1) and 2 (DCL2) genes of Botrytis cinerea. In this study, we demonstrate that both solutions based on dsRNA topical treatment and in planta expression targeting BcDCL1 and BcDCL2 genes can be used to control the strawberry gray mold, the most harmful disease for different fruit crops. 50, 70 and 100 ng μL−1 of naked BcDCL1/2 dsRNA, sprayed on plants of Fragaria x ananassa cultivar Romina in the greenhouse, displayed significant reduction of susceptibility, compared to the negative controls, but to a lesser extent than the chemical fungicide. Three independent lines of Romina cultivar were confirmed for their stable expression of the hairpin gene construct that targets the Bc-DCL1 and 2 sequences (hp-Bc-DCL1/2), and for the production of hp construct-derived siRNAs, by qRT-PCR and Northern blot analyses. In vitro and in vivo detached leaves, and fruits from the hp-Bc-DCL1/2 lines showed significantly enhanced tolerance to this fungal pathogen compared to the control. This decreased susceptibility was correlated to the reduced fungal biomass and the downregulation of the Bc-DCL1 and 2 genes in B. cinerea. These results confirm the potential of both RNAi-based products and plants for protecting the cultivated strawberry from B. cinerea infection, reducing the impact of chemical pesticides on the environment and the health of consumers.

Glyphosate and other plant protection products in size-segregated urban aerosol: Occurrence and dimensional trend

Plant protection products (PPPs) play a fundamental role in the maintenance of agricultural fields and private/public green areas, however they can contaminate zones nearby the application point due to wind drift, resuspension, and evaporation. Several studied have deepened the relationship between PPPs and living beings’ health, suggesting that these products might have a negative influence. Some PPPs belong to the class of Emergent Contaminants, which are compounds whose knowledge on the environmental distribution and influence is limited. These issues are even more stressed in urban aerosol, due to the high residential density that characterizes this area. Therefore, this study assessed the contamination caused by polar PPPs, such as herbicides (i.e., Glyphosate), fungicides (i.e., Fosetyl Aluminium), and growth regulators (i.e. Maleic Hydrazide), in size-segregated urban aerosol and evaluated their concentration variability with respect to atmospheric parameters (humidity, temperature, rain). Moreover, hypotheses on possible sources were formulated, exploiting also back-trajectories of air masses. A total of six PPPs were found in the samples: glyphosate was more present in the coarse fraction (2.5–10 μm), Fosetyl Aluminium, chlorate and perchlorate were more present in the coarse/fine fractions (10-1 μm), while cyanuric acid and phosphonic acid were mostly concentrated in the fine/ultrafine fractions (<1 μm). While for the first four we suspect of local sources, such as private gardening, the two latter might derive from the entire Po Valley, a highly polluted area in the North of Italy, and from degradation of other substances.

Drone Technology for Crop Disease Resistance: Innovations and Challenges

Drones have been used for diverse application purposes in precision agriculture and new ways of using them are being explored. Many drone applications have been developed for different purposes such as pest detection, crop yield prediction, crop spraying, yield estimation, water stress detection, land mapping, identifying nutrient deficiency in plants, weed detection, livestock control, protection of agricultural products and soil analysis. Drones can create georeferenced maps that pinpoint the exact location of disease outbreaks within a field. These maps help farmers and agronomists monitor disease progression and plan targeted interventions. Drone operations are highly dependent on weather conditions. High winds, rain, and fog can hinder drone flights and affect the quality of images captured. Addressing technical limitations, regulatory and safety concerns, economic barriers, and data management issues will be crucial for the widespread adoption of drones in agriculture. By overcoming these challenges, drone technology can become a vital tool in sustainable and effective crop disease management.

Imidacloprid Uptake and Accumulation in Lettuce Plant (Lactuca sativa L. var. longipolia) and Its Effects on Abundance of Microbial Communities in Cultivated and Non-Cultivated Arid Soil.

Systemic plant protection products, such as neonicotinoids (NIs), are capable of being translocated throughout a plant. Although NIs are less toxic to mammals, fish, and birds, their impact on microbial and non-target insects is of concern. This study investigates the uptake, translocation, and accumulation of the NI, imidacloprid (IMI), in romaine lettuce (Lactuca sativa L. var. longipolia). Exposing 15-day-old seedlings to "10 mg/L" of IMI, the effects on microbial communities in both cultivated (CS) and non-cultivated soil (NCS) were studied along with IMI translocation within plant tissues. The concentrations of IMI in soil varied temporally and between soil types after initial application, with a decrease from 2.0 and 7.7 mg/kg on the first day of sampling to 0.5 and 2.6 mg/kg on the final sampling day (day 35) for CS and NCS, respectively. The half-life of IMI soil was 10.7 and 72.5 days in CS and NCS, respectively, indicating that IMI degraded more quickly in CS, possibly due to smaller grain size, aeration, microbial degradation, and water flow. The accumulated concentrations of IMI in lettuce tissues ranged from 12.4 ± 0.2 and 18.7± 0.9 mg/kg in CS and NCS, respectively. The highest concentration of IMI was found in the shoots, followed by the roots, whereas the soil showed the lowest IMI residuals at the end of the trial. Soil bacteria and fungi were altered by the application of IMI, with a lower abundance index within the bacterial community, indicating a negative impact on the distribution of bacteria in the soil.

Antibiotic feeding changes the bacterial community of Chilo suppressalis and thereby affects its pesticide tolerance

BackgroundOwing to the widespread use of chemical pesticides to control agricultural pests, pesticide tolerance has become a serious problem. In recent years, it has been found that symbiotic bacteria are related to pesticides tolerance. To investigate the potential role of microorganisms in the pesticide tolerance of Chilo suppressalis, this study was conducted.ResultsThe insect was fed with tetracycline and cefixime as the treatment group (TET and CFM, respectively), and did not add antibiotics in the control groups (CK). The 16S rDNA sequencing results showed that antibiotics reduced the diversity of C. suppressalis symbiotic microorganisms but did not affect their growth and development. In bioassays of the three C. suppressalis groups (TET, CFM, and CK), a 72 h LC50 fitting curve was calculated to determine whether long-term antibiotic feeding leads to a decrease in pesticide resistance. The CK group of C. suppressalis was used to determine the direct effect of antibiotics on pesticide tolerance using a mixture of antibiotics and pesticides. Indirect evidence suggests that antibiotics themselves did not affect the pesticide tolerance of C. suppressalis. The results confirmed that feeding C. suppressalis cefixime led to a decrease in the expression of potential tolerance genes to chlorantraniliprole.ConclusionsThis study reveals the impact of antibiotic induced changes in symbiotic microorganisms on the pesticide tolerance of C. suppressalis, laying the foundation for studying the interaction between C. suppressalis and microorganisms, and also providing new ideas for the prevention and control of C. suppressalis and the creation of new pesticides.

CONSUMPTION OF FERTILIZER AND PESTICIDES IN TELANGANA: SMALL AND MARGINAL FARMERS’ CHALLENGES

The industrialization of agriculture has favoured the use of plenty of agrochemicals including fertilizers, pesticides, micronutrients. Consumption of pesticides has become an integral part of modern agriculture and is an effective and economical way to enhance the yield quality and quantity. Approximately, 2 million metric tons (MT) of pesticides are utilized annually worldwide. India stands 12th in pesticide use globally and 3rd in Asia after China. India shares only 1% of the global pesticide use. After the green revolution, there is increased use of chemical pesticides which resulted in contaminating the environment and the long-term implications on the society. Indiscriminate and excessive application of pesticides not only have damaged the environment but also have entered the food chain thereby affecting health and development. However, the role of pesticides in augmenting agricultural output has been well perceived and these have been considered as essential inputs in agricultural production. The present paper aimed to study the consumption pattern of pesticides and fertilizers among the small and marginal farmers. This study also aimed to know the farmers’ knowledge about the safe handling and application of pesticides and their practices on pesticide usage. While doing so, it highlights some issues like change in the cropping pattern among small and marginal farmers and also emphasizes on soil degradation and environmental issues.

Investigating the Effects of Bamboo Vinegar as An Organic Pesticide on Insect Pests and the Nutrient Content of Harumanis Mango (MA128), Mangifera indica L.

Chemical pesticides have been widely used in plantations, and their effects have more disadvantages to the environment as well as to humans. Therefore, this study tries to implement organic pesticides using bamboo vinegar. Bamboo vinegar is one of the organic pesticides to control insect pests in plantation crops. The role of this organic pesticide on the insect pests of Harumanis mango is still unknown. Hence, this study aims to determine the impact of applying bamboo vinegar on the insect pests, quality, and nutrient content of Harumanis mango (MA128). Bamboo vinegar was applied in February 2021 during the flowering phase at the Harumanis plot in the Plantation Unit, Universiti Teknologi MARA Perlis. This study used a randomized complete block design with three treatments (spraying intervals) and three replications: T1 (3-day interval), T2 (5-day interval), and T3 (no bamboo vinegar). Sticky traps were installed to determine the population of insect pests in Harumanis mango. Matured fruits have been harvested, and the standard procedure of Harumanis mango postharvest handling has been followed. Then, the fruits were determined for total phenolic content (TPC), total flavonoid content (TFC), vitamin C, and sugar content. Bamboo vinegar significantly reduced the abundance of insects in Harumanis mango. Additionally, the highest TPC was observed from a 3-day interval of bamboo vinegar application. A similar trend was indicated for improving TFC with bamboo vinegar application. Similarly, there was a significantly higher vitamin C and sugar content after bamboo vinegar application compared to the control group. In conclusion, applying bamboo vinegar to Harumanis mango reduced insect pests and increased the quality and nutrient content of the Harumanis mango.

Влияние применения различных гуминовых препаратов на формирование урожая и качество зернофуражного ячменя

The results of studies on the effectiveness of seed treatment and plant spraying with various humic preparations on spring grain feed barley are presented. The objectives of the research included assessing the effect of various humic preparations on productivity, disease resistance and grain quality of spring barley under various methods of their application (seed treatment, plant spraying, seed treatment + plant spraying). The objects of research were spring two-row barley of the Raushan variety. Humic preparations Bigus and Gumat +7 were used. The research was carried out in 2022-2023 on gray forest, medium loamy soil. In 2022, moisture conditions during the growing season were favorable; in 2023, periodic severe drought events were observed. The use of humic preparations led to a decrease in the development of both leaf diseases (dark brown spot) and root rot. The drug Bigus Extra had a more pronounced effect on reducing the damage to plants by root rot. The use of humic preparations had a positive effect on the length of the stem and ear of barley. The maximum values of the stem length were when using seed treatment and spraying crops with Bigus Extra, and the greatest length of the ear was when using Gumi+7. The use of humic preparations increases the yield of spring barley from 11 to 27.8%. When using only seed treatment or only spraying of crops, Bigus Extra had an advantage in yield, and when using a combination – seed treatment + plant treatment Humat +7. The highest yield of spring barley (27.8% more than in the control) was obtained using a scheme in which seeds and plants were treated with Humate +7. The use of seed treatment followed by spraying of plants led to an increase in the protein content of barley grain. The use of humic preparations in which they are used for pre-sowing seed treatment and subsequently for spraying crops (twice) was optimal for spring barley.

A Review of Plant Growth Promoting Rhizobacteria and Their Characteristics as Potential Biofertilizer

The growing demand for agricultural products for food requirements caused the use of excessive inorganic chemical fertilisers, insecticides, fungicides, and pesticides for a quick and simple way to maximise and boost crop yield. This practice harmed food safety and caused the degradation of environmental, physical, and biological conditions. It has become alarming, and now is the time for a greener approach to increase agricultural output while minimising the use of inorganic chemical fertilisers. It was proven through many previous studies that using environmentally friendly biofertilisers has managed to increase crop yield while reducing the usage of chemical fertilisers. Plant growth-promoting rhizobacteria (PGPR) are mostly used in biofertiliser production because these types of microbes will enhance plant growth and yield by mobilising the available nutrients through several biological mechanisms, including fixation of atmospheric nitrogen, solubilisation, and mobilisation of phosphate and potassium, phytohormones production, disease suppression, and stress protection. Understanding their characteristics, biological mechanisms of action, and the nutritional and physical requirements for growth is important for successfully formulating and applying PGPR as a biofertiliser. The selection of the right PGPR with the desired characteristics, the ability to adapt to the environment, and the ideal formulation of the biofertiliser are the main criteria that should be emphasised when determining the success of biofertiliser. Knowledge and awareness regarding the use, benefits, and production of PGPR as a potential biofertiliser are important and should be explored to fulfil the crop’s nutritional requirements more economically and sustainably.

Effect of bariatric surgery in the body burden of persistent and non-persistent pollutants: longitudinal study in a cohort of morbidly obese patients.

Obesity is a pathological state that involves the dysregulation of different metabolic pathways and adipose tissue cells, constituting a risk factor for the development of other diseases. Bariatric surgery is the most effective treatment. The study of the behavior of pollutants in situations of extreme weight loss can provide biomonitoring information and tools to manage diseases of environmental etiology. To determine the prevalence of serum persistent and non-persistent pollutants in obese patients subjected to bariatric surgery and analyze the impact of sociodemographic variables on these changes. GC-MS/MS and UHPLC-MS/MS were utilized to determine the detection rates and concentrations of 353 compounds, including persistent organic pollutants (POPs), pesticides, pharmaceuticals, and rodenticide, in serum samples of 59 obese patients before and after undergoing bariatric surgery. Detection rates of p,p'-DDE, HCB, β-HCH, naphthalene, phenanthrene and PCB congeners 138, 153 and 180 significantly increased due to surgery-induced weight loss. Serum levels of p,p'-DDE, PCB-138, PCB-153 and PCB-180 also increased after surgery. Correlations between naphthalene levels, weight loss, variation of total lipids and time after surgery were found. Additionally, correlations were observed between concentrations of PCB-138 and weight loss, and between phenanthrene levels and reduction of total lipids. No statistically significant differences were observed for other groups of contaminants, pharmaceuticals and other chemicals included in the quantification methods. Increment of POPs was observed after bariatric surgery. Serum concentrations of POPs after surgery were influenced by adiposity-related variables. Although biomonitoring studies show a decreasing tendency of exposure, rapid weight loss leads to an increase of circulating POPs. Further research on the interplay between adipose tissue, POPs and peripheral organs is required.

Phytochemical Analysis and Antioxidant and Antifungal Activities of Powders, Methanol Extracts, and Essential Oils from Rosmarinus officinalis L. and Thymus ciliatus Desf. Benth.

Chemical residues in food pose health risks such as cancer and liver issues. This has driven the search for safer natural alternatives to synthetic fungicides and preservatives. The aim of this study was to characterize the chemical composition of the essential oils (EO), determine the polyphenolic contents, and evaluate the in vitro antioxidant and antifungal activities of methanol extracts (ME), essential oils (EO), and powders from Rosmarinus officinalis L. (rosemary) and Thymus ciliatus (Desf) Benth. (thyme) from the M'sila region, Algeria. The chemical composition of the EOs was determined by GC-MS. R. officinalis EO was composed of 31 components, mainly camphor (41.22%), camphene (18.14%), and α-pinene (17.49%); T. ciliatus EO was composed of 58 components, mainly, in percentage, α-pinene (22.18), myrcene (13.13), β-pinene (7.73), β-caryophyllene (10.21), and germacrene D (9.90). The total phenols and flavonoids were determined spectrophotometrically, and the rosemary ME was found to possess the highest polyphenolic content (127.1 ± 2.40 µg GAE/mg), while the thyme ME had the highest flavonoid content (48.01 ± 0.99 µg QE/mg). The antioxidant activity was assessed using three methods: rosemary ME was the most potent, followed by DPPH (IC50 = 13.43 ± 0.14 µg/mL), β-carotene/linoleic acid (IC50 = 39.01 ± 2.16 μg/mL), and reducing power (EC50 = 15.03 ± 1.43 µg/mL). Antifungal activity was assessed for 32 pathogenic and foodborne fungi. Four methods were applied to the solid medium. Incorporating the powdered plant into the culture medium (at 10%) reduced the fungal growth to greater than 50% in 21.88% and 6.25% of all fungal isolates, for R. officinalis and T. ciliatus, respectively. The ME, applied by the well diffusion method (0.1 g/mL), was less effective. Different concentrations of EO were tested. Incorporating the EO into the culture medium (1500 μL/L) inhibited 50% of the molds to levels of 50 and 75% for R. officinalis and T. ciliatus, respectively, with the complete inhibition of four fungi. Fumigated EO (15 μL) inhibited 65% of the molds to levels of 65 and 81.25% for R. officinalis and T. ciliatus, respectively, with the complete inhibition of five fungi. There was little to no sporulation in conjunction with the inhibition. Our results revealed some of the potential of the studied plants to fight foodborne molds and presented their promising characteristics as a source of alternatives to chemical pesticides and synthetic preservatives. Further studies are needed to find adequate application techniques in the food safety area.

Actinobacteria mediated synthesis of silver nanoparticles using Streptomyces diastaticus and their biological efficacy against human vector mosquitoes and agricultural insect pests

Mosquitoes and agricultural insects were harmful to both public health and crops. Prolonged use of synthetic chemical pesticides for insect pest control was associated with resistance development and negative human and ecological effects. This study investigates the larvicidal activity of Ag-NPs produced using Streptomyces diastaticus against Culex quinquefasciatus, Anopheles stephensi, Aedes aegypti, Spodoptera litura, and Plutella xylostella. UV-Vis spectroscopy, XRD, SEM-EDX, FT-IR, TEM, DLS, and Zeta potential analysis were used to characterize the biosynthesized Ag-NPs. The results showed that biosynthesized Ag-NPs were more toxic to, A. stephensi, C. quinquefasciatus, and A. aegypti with LC50 values of 15.70, 11.10, and 17.53 µg/mL, respectively. Biosynthesized Ag-NPs exhibited the highest antifeedant effects against S. litura (88.73 %) and P. xylostella (92.36 %) at 50 µg/mL concentration. The mortality bioassay revealed considerable larvicidal activity against S. litura and P. xylostella larvae at greater doses of 50 µg/mL, 80.67 and 84.05 %, respectively. Morphogenetic variations were observed on treated larvae of C. quinquefasciatus, A. aegypti, and A. stephensi, S. litura, and P. xylostella with Ag-NPs. In the present investigation the impact of Ag-NPs on the antioxidant enzymes (SOD, CAT, and GPx), the activity of each enzyme were dramatically increased with higher concentrations resulting in significant differences. The study also found that Ag-NPs inhibited the detoxifying enzyme (GST and AChE) activity of target organisms. The histological structure of the treated and untreated larvae revealed structural changes between the midgut epithelial cells. As a consequence of these findings, the S. diastaticus-mediated Ag-NPs serve as a possible, eco-friendly biopesticide and alternative to synthetic chemicals for the control of human vector mosquitoes and destructive arthropod insect pests.

Separation of plant protection products from complex aqueous bodies using carbon-mineral composites incorporated with double metals (Ni/Mn or Ni/Fe)

Due to the extensive application of pesticides and their hazardous effects on organisms, there is an urgent need to remove them effectively from wastewater. Metal-incorporated carbon-mineral composites (Ni/Mn-CMC and Ni/Fe-CMC) described in this paper can certainly be applied for this purpose. They were synthesized by combining mechanochemical and pyrolytic processes and their physicochemical properties were investigated using numerous methods (SEM-EDS, N2 adsorption/desorption, XRD, surface charge, FTIR). Adsorption capacity towards diuron and carboxin with and without impurities commonly detected in natural ecosystems, cadmium ions or arsenite, was measured. The obtained results indicated that Ni/Fe-CMC is more efficient adsorbent of pesticides due to its well-developed surface. It was able to bind 158.34 mg g−1 of diuron and 133.58 mg g−1 of carboxin in the solutions, where only one pesticide was present. In turn, these values for the Ni/Mn-CMC sample were 126.49 mg g−1 and 102.08 mg g−1, respectively. It should be noted that the composites maintained their high adsorption capacity in the multicomponent solutions, i.e., containing both pesticide and metal ions. Then, the maximum reduction in pesticide adsorption was only 8.36. Ni/Mn-CMC and Ni/Fe-CMC were successfully regenerated with ethanol without changing their structure and adsorption capacity. Also, the extracts from investigated materials did not have negative impact on plant growth. This confirmed suitability of carbon-mineral composites for repeated multiple use without toxic effects to organisms.

Applications of chitosan in the agri-food sector: A review

Chitosan is a natural and renewable polysaccharide that can form biopolymers. It is derived from the deacetylation of chitin mainly from crustaceans' shells, but also from fungi and insects. Thanks to unique characteristics such as antimicrobial effects, antioxidant properties or film forming capacities, it has triggered an important amount of research in the last decade about possible applications in industrial fields. The main application field of chitosan is the food industry where it can be used for preservation purposes and shelf-life improvement for fresh food products such as fruits or meat. For beverages, it is used for clarification and fining as well as elimination of spoilage flora in beverages like fruit juices or wine. And in agriculture, it can be used as a plant protection product through different mechanisms like the elicitation of plant defences. The mechanisms of action of chitosan on microorganisms are multiple and complex but revolve mostly around the disturbance of microorganisms’ membranes and cell walls resulting in the leakage of cell material. The use of chitosan is still minor but is promising in finding environmentally friendly alternatives to synthetic chemicals and plastics. Therefore, its characterization is primordial for the future of sustainable production and preservation processes.

MODELING THE EFFECTS OF PESTS AND PESTICIDE ON CROP YIELDS IN A MULTIPLE CROPPING SYSTEM

Pest infestation poses a significant threat to agricultural crop yields, and to control it, farmers spray chemical pesticides. The persistent use of these chemical agents not only leads to pesticide residues within crops but also exerts collateral damage on the beneficial pest population. In this research work, we formulate a nonlinear mathematical model to assess the impacts of pesticide on crop yields within a multiple cropping system. Model analysis illustrates that crop consumption rates destabilize, and the spraying rate of pesticide stabilizes the system. Furthermore, we determine conditions for the global stability of the coexisting equilibrium and conduct a global sensitivity analysis to identify model parameters that significantly influence pest population density. Our findings emphasize that, for effective pest population control and enhanced crop yields, farmers should choose either pesticides with a high pest abatement rate or those with a higher pesticide uptake rate. Considering the spraying rate of pesticide as time-dependent, we also suggest an optimal control strategy to minimize the pest population and associated costs. We provide analytical results backed by numerical simulations implemented through the non-standard finite difference scheme to support our findings.

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

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. 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. 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.

Comparison between Liquid Immersion, Laser Diffraction, PDPA, and Shadowgraphy in Assessing Droplet Size from Agricultural Nozzles

Spray droplet diameters play a key role in the field of liquid plant protection product (PPP) application technology. However, the availability of various measurement techniques, each with its unique operating principles for evaluating droplet size spectra, can lead to different interpretations of spray characteristics. Therefore, in this study, four measurement techniques—Liquid Immersion (LI), Laser Diffraction (LD), Phase Doppler Particle Analysis (PDPA), and Shadowgraphy (SG)—were utilized to evaluate the droplet size distribution of agricultural spray nozzles. Additionally, PDPA and SG were used to assess the average velocity of spray droplets. Experiments were conducted in three different laboratories with the main aim of comparing results obtained with various types of equipment utilized under ordinary practical conditions. Spraying tests were carried out using three flat fan nozzles and an air-induction flat fan nozzle. As a general trend, the lowest values for droplet diameters were measured using the Laser Diffraction technique, followed by Shadowgraphy. The PDPA technique provided the highest values for mean diameters (D10, D20, and D30) and the numeric median diameter (Dn0.5), whereas the Liquid Immersion method yielded the highest values for the Sauter mean diameter (D32) and volumetric diameters (Dv0.1, Dv0.5, and Dv0.9). Importantly, all measurement techniques were able to discriminate the four nozzles based on their Dv0.5 diameter. Average droplet velocities showed a similar pattern across the four nozzles with the PDPA and the SG measurement techniques. The differences in diameter values observed with the four measurement techniques underline the necessity of always including reference nozzles in spray quality assessments to base classifications on relative rather than absolute values.

Biopesticide effect on crops for the bioactive components extracted from Tagetes erecta and Tagetes patula

Botanicals from Marigold, Chrysanthemum, Basil, Rosemary and other medicinal plants have been analysed as potential replacements of chemical pesticides as they are effective and non-hazardous to the environment. The bioactive components thiophene is present in large amount in Tagetes sp. which have a wide range of biocidal properties. In this study the crude extracts of different parts of Tagetes erecta and Tagetes patula were obtained by Soxhlet extraction method. The leaf extracts were subjected to GC–MS to identify their components and to confirm the presence of thiophenes. Two major disastrous crop pests namely, Spodoptera litura and Corcyra cephalonica belongs to Order Lepidoptera, Family Noctuidae and Pyralidae were used for the experimental study. The effect of bioactive extract was tested by direct and indirect methods for their larvicidal effect. The S. litura larvae was allowed to feed on castor leaves coated with spraying different concentrations of methanolic sample extracts as indirect method. In the direct spraying method, the S. litura and C. cephalonica larvae were sprayed with low and high concentrations of crude sample extracts of both T. patula and T. erecta. Significant decrease in larval activity and survival rate within 24 h to 48 h were recorded for both the methods. The trials were performed using variousvolumes from 10 to 1000 µl to check larvicidal activity. The roots and stem extracts of T. erecta for 25 µl kill 100% larvae within 24 h whereas 50 µl of T. patula flowers, roots and stem extract effectively kill only 50% of the larvae in 48 h. A mini nursery evaluation were conducted by direct spraying method on larvae growing on jowar saplings, which displayed 100% mortality of larvae within 24 h for 25 µl of T. erecta leaf and flower extracts and T. patula flower extract. From these trials, it can be inferred that the extracts of T. patula and T. erecta provided effective outcomes as larvicides of S. litura and C. cephalonica.

Optimizing the production of dsRNA biocontrols in microbial systems using multiple transcriptional terminators.

Crop pests and pathogens annually cause over $220 billion in global crop damage, with insects consuming 5%-20%of major grain crops. Current crop pest and disease control strategies rely on insecticidal and fungicidal sprays, plant genetic resistance, transgenes, and agricultural practices. Double-stranded RNA(dsRNA) is emerging as a novel sustainable method of plant protection as an alternative to traditional chemical pesticides. Successful commercialization of dsRNA-based biocontrols requires the economical production of large quantities of dsRNA combined with suitable delivery methods to ensure RNAi efficacy against the target pest. In this study, we have optimized the design of plasmid DNA constructs to produce dsRNA biocontrols in Escherichia coli, by employing a wide range of alternative synthetic transcriptional terminators before measurement of dsRNA yield. We demonstrate that a 7.8-fold increase of dsRNA was achieved using triple synthetic transcriptional terminators within a dual T7 dsRNA production system compared to the absence of transcriptional terminators. Moreover, our data demonstratethat batch fermentation production dsRNA using multiple transcriptional terminators is scalable and generates significantly higher yields of dsRNA generated in the absence of transcriptional terminators at both small-scale batch culture and large-scale fermentation. In addition, we show that application of these dsRNA biocontrols expressed in E. coli cells results in increased insect mortality. Finally, novel mass spectrometry analysis was performed to determine the precise sites of transcriptional termination at the different transcriptional terminators providing important further mechanistic insight.