Crop Protection Research Articles

Design, synthesis, bioactivity and action mechanism of N-substituted N'-phenylpicolinohydrazides against phytopathogenic fungi.

N'-phenylpicolinohydrazide has been proven to be a promising lead compound for research and development of novel fungicides for agriculture in our previous study. As our continuing research, in this study, a series of N-substituted derivatives of N'-phenylpicolinohydrazide were synthesized and explored for the inhibition activity on nine phytopathogenic fungi and action mechanism. The results found that eleven of the compounds had excellent antifungal activity with more than 80% inhibition rates at 50 µg/mL on part or most of the fungi, especially A. solani and P. piricola. Compounds 5i, 5j and 5k showed EC50 values of < 8.0 µg/mL against A. solani superior to positive control carbendazim (EC50 = 36.0 µg/mL) while 5p and 5q exhibited the highest activity with EC50 values of 2.72 and 2.80 µg/mL against P. piricola superior to positive control boscalid (EC50>50.0 µg/mL). Furthermore, 5k also showed significant protective effect against A. solani infection on tomatoes in a concentration-dependent manner. Action mechanism research showed that 5k was able to increase the intracellular ROS level, change both MMP and permeability of cell membrane and damage mycelial morphology. Molecular docking studies showed that 5k could bind into ubiquinone-binding region of succinate dehydrogenase by hydrogen bonds, π-cation, π-π stacked, π-alkyl, and alkyl interactions. Additionally, the antibacterial activity was also investigated. Thus, N-substituted derivatives of N'-phenylpicolinohydrazide were emerged as novel and highly promising antifungal molecular skeletons to develop new fungicides for crop protection.

Improving UASS pesticide application: optimizing and validating drift and deposition simulations.

As unmanned aerial spraying systems (UASS) usage grows rapidly worldwide, a critical research study was conducted to optimize the simulation of UASS applications, aiming to enhance pesticide delivery efficiency and reduce environmental impact. The study examined several key aspects for accurate simulation of UASS application with lattice Boltzmann method (LBM). Based on these discussions, the most suitable grid size and simulation parameters were selected to create a robust model for optimizing UASS performance in various pest management scenarios, potentially leading to more targeted and sustainable pest control practices. The effect of stability parameter, grid size around the rotor and near ground, and parameters at wake flow were carefully analyzed to improve the precision of pesticide drift predictions and deposition patterns. Optimal grid sizes were identified as 0.2 m generally, 0.025 m near rotors, and a 0.1 + 0.2 m scheme for ground proximity, with finer grids improving accuracy but increasing computation time. Wake resolution and threshold significantly influenced simulation results, while wake distance had minimal impact beyond a certain point. The LBM's accuracy was validated by comparing simulated downwash flow and droplet deposition with field test data. This study optimized UASS simulation parameters, balancing computational efficiency with accuracy. The validated model enhances our ability to design more effective UASS for pest management, potentially leading to more precise and targeted pesticide applications. These advancements contribute to the development of sustainable pest control strategies, aiming to reduce pesticide usage and environmental impact while maintaining crop protection efficacy. © 2024 Society of Chemical Industry.

A History of Community Based Initiatives that Led to Crop Improvement and Protection in the Canadian Prairies

From the early days of agricultural production in the 1800s through to the present day, farmers, agronomists, and other motivated people have worked to improve crop production through pest management and surveillance, selection of crop genotypes and agronomic innovations such as reduced and zero-tillage. These essential contributions also helped raise awareness of the practical problems that farmers have faced, of the potential solutions to those problems, and the problems that remain to be solved. In many cases, farmers have organized their efforts to support research to address agricultural challenges through commodity organizations who actively fund research, raise awareness of science, and encourage participation in activities such as pest monitoring and on-farm research trials. The future of a biovigilance approach to crop production depends on the continued participation of agricultural community members.

Plant versus pollinator protection: balancing pest management against floral contamination for insecticide use in Midwestern US cucurbits.

Controlling crop pests while conserving pollinators is challenging, particularly when prophylactically applying broad-spectrum, systemic insecticides such as neonicotinoids. Systemic insecticides are often used in conventional agriculture in commercial settings, but the conditions that optimally balance pest management and pollination are poorly understood. We investigated how insecticide application strategies control pests and expose pollinators to insecticides with an observational study of cucurbit crops in the Midwestern United States. To define the window of protection and potential pollinator exposure resulting from alternative insecticide application strategies, we surveyed 62 farms cultivating cucumber, watermelon, or pumpkin across 2 yr. We evaluated insecticide regimes, abundance of striped and spotted cucumber beetles (Acalymma vittatum [Fabricius] and Diabrotica undecimpunctata Mannerheim), and insecticide residues in leaves, pollen, and nectar. We found that growers used neonicotinoids (thiamethoxam and imidacloprid) at planting in all cucumber and pumpkin and approximately half of watermelon farms. In cucumber, foliar thiamethoxam levels were orders of magnitude higher than the other crops, excluding nearly all beetles from fields. In watermelon and pumpkin, neonicotinoids applied at planting resulted in 4-8wk of protection before beetle populations increased. Floral insecticide concentrations correlated strongly with foliar concentrations across all crops, resulting in high potential exposure to pollinators in cucumber and low-moderate exposure in pumpkin and watermelon. Thus, the highest-input insecticide regimes maintained cucumber beetles far below economic thresholds while also exposing pollinators to the highest pollen and nectar insecticide concentrations. In cucurbits, reducing pesticide inputs will likely better balance crop protection and pollination, reduce costs, and improve yields.

Harnessing the antagonistic potential and unraveling the bioactive compounds of Streptomyces sp. isolate WAB2 to protect watermelon crop from Colletotrichum orbiculare

ABSTRACT Watermelon (Citrullus lanatus Thumb) is a significant vegetable crop globally and is prone to anthracnose disease caused by Colletotrichum spp. The use of chemical fungicides for managing crop diseases has adverse impacts on the environment and human health. Therefore, it is important to use biocontrol agents for disease management. In this study, streptomycetes were assessed as a potential biocontrol agent against anthracnose pathogen, Colletotrichum orbiculare WEC2. The potent Streptomyces sp. isolate WAB2 was isolated from healthy watermelon plants and showed remarkable antifungal efficacy against C. orbiculare WEC2. Rigorous assays confirmed its performance against C. orbiculare WEC2. Bioactive compounds produced by Streptomyces sp. isolate WAB2 were identified using Gas Chromatography–Mass Spectrometry (GC–MS). An SEM study indicated the parasitic action of Streptomyces sp. isolate WAB2 against the pathogen. The formulated talc-based product of Streptomyces sp. isolate WAB2 was effective when applied as a seed treatment + foliar spray against C. orbiculare WEC2 under pot culture conditions. These treatments reduced the disease incidence (31.81%) and exhibited a higher disease reduction (52.56%), compared to the untreated control. Therefore, treatment with talc-based Streptomyces sp. isolate WAB2 is a sustainable solution for anthracnose disease management, and it facilitates eco-friendly crop protection practices against the disease in watermelon. RESEARCH HIGHLIGHTS Isolated streptomycete strains from healthy watermelon plants and screened for its efficacy against the pathogen, Colletotrichum orbiculare WEC2. Streptomyces sp. isolate WAB2 showed significant antifungal activity against the pathogen. Bio-active compounds produced by Streptomyces sp. isolate WAB2 was identified by Gas Chromatography–Mass Spectrometry (GC–MS). Using scanning electron microscopy (SEM), the parasitic activity of Streptomyces sp. isolate WAB2 against the pathogen was detected. Developed a talc-based formulation of Streptomyces sp. isolate WAB2 and tested it as a seed treatment plus foliar spray, effectively reducing the disease incidence.

In Vitro Predictions of Acute Fish Toxicity for Development of Sustainable Crop Protection Products.

New agrochemicals must demonstrate safety to numerous ecological systems, including aquatic systems, and aquatic vertebrate toxicity is typically evaluated by using the in vivo acute fish toxicity (AFT) test. Here, we investigated two alternative in vitro assays using a cell line isolated from rainbow trout (Onchorhynchus mykiss) gill tissue: (i) adenosine triphosphate (ATP) luminescence and (ii) cell painting. The former assay measures cytotoxicity, while the latter measures changes in cellular morphology in response to chemical exposure. We assessed how well end points in these two assays predicted acute lethality (i.e., LC50 values) in independent in vivo AFT tests. When compared to results from OECD TG 249 (in vitro), we found that the ATP assay was not as predictive (R2 = 0.53) as the cell painting assay. Similarly, when compared to results from OECD TG 203 (in vivo), the cell painting was much more predictive (R2 = 0.67). Our results show that such in vitro assays are useful for fast and efficient screening alternatives to in vivo fish testing that can aid in the agrochemical discovery phase, where thousands of potential new actives are tested each year.

Leveraging In Silico Structure-Activity Models to Predict Acute Honey Bee (Apis mellifera) Toxicity for Agrochemicals.

In the realm of crop protection products, ensuring the safety of pollinators stands as a pivotal aspect of advancing sustainable solutions. Extensive research has been dedicated to this crucial topic as well as new approach methodologies in toxicity testing. Hence, within the agricultural and chemical industries, prioritizing pollinator safety remains a constant objective during the development of predictive tools. One of these tools includes computational models like quantitative structure-activity relationships (QSARs) that are valuable in predicting the toxicity of chemicals. This research uses bee toxicity data to develop artificial neural network classification models for predicting honey bee acute toxicity. Bee toxicity data from 1542 compounds were used to develop models; the sensitivity and specificity of the best model were 0.90 and 0.91, respectively. These in silico models can aid in the discovery of next-generation crop protection products. These tools can guide the screening and selection of next-generation crop protection molecules with high margins of safety to pollinators, and candidates with favorable sustainability profiles can be identified at the early discovery stage as precursors to in vivo data generation.

Selected farm-level crop protection practices in Europe and Argentina: Opportunities for moving toward sustainable use of pesticides

Extensive use of plant protection products (PPP) in the last decades contributes to negative impacts on ecosystems, animals and humans. For the strategies of PPP reduction and replacement of hazardous pesticides, farm-level data on agronomic management practices and crop protection applications are crucial. In this study, we strategically collected data for the 2021 season at the SPRINT project case study sites (CSS) in 10 European countries and Argentina, on perennial, arable and vegetable crops. Data collection included strategically selected farm and field data, pesticide records and farming practices. Results involved more than 1700 recorded PPP applications across various crops with more than 170 different active substances from PPP in organic, integrated pest management and conventional farming practices. We explored differences in application patterns (fungicides, insecticides, herbicides and non-PPP, e.g. adjuvants, growth regulators, and fertilizers) between and within crops, countries and farming systems and calculated the costs of PPP use. The pesticide dosages applied during the crop season varied up to a factor of 20 around recommended doses. Regarding the costs of PPPs use perennial crops had the highest costs per ha crop production area. Finally, we analysed the active substances applied in different farming systems in terms of their hazard statements. Our results shed light on how PPPs are used across different crop and farming types and will help elucidate how pesticide application patterns can be changed in the future. Finally, we highlighted non-PPP use practices which help to reduce dependency on PPP use. This might be used to support decision-making and policies within agricultural advisory/support systems.

Genetic analysis of tomato brown rugose fruit virus reveals evolutionary adaptation and codon usage bias patterns

Tomato brown rugose fruit virus (ToBRFV) poses a significant threat to tomato production worldwide, prompting extensive research into its genetic diversity, evolutionary dynamics, and adaptive strategies. In this study, we conducted a comprehensive analysis of ToBRFV at the codon level, focusing on codon usage bias, selection pressures, and evolutionary patterns across multiple genes. Our analysis revealed distinct patterns of codon usage bias and selection pressures within the ToBRFV genome, with varying levels of genetic diversity and evolutionary constraints among different genes. We observed a transition/transversion bias of 2.07 across the entire ToBRFV genome, with the movement protein (MP) gene exhibiting the highest transition/transversion bias and SNP density, suggesting potential evolutionary pressures or a higher mutation rate in this gene. Furthermore, our study identified episodic positive selection primarily in the MP gene, highlighting specific codons subject to adaptive changes in response to host immune pressures or environmental factors. Comparative analysis of codon usage bias in the coat protein (CP) and RNA-dependent RNA polymerase (RdRp) genes revealed gene-specific patterns reflecting functional constraints and adaptation to the host's translational machinery. Our findings provide valuable insights into the molecular mechanisms driving ToBRFV evolution and adaptation, with implications for understanding viral pathogenesis, host-virus interactions, and the development of control strategies. Future research directions include further elucidating the functional significance of codon usage biases, exploring the role of episodic positive selection in viral adaptation, and leveraging these insights to inform the development of effective antiviral strategies and crop protection measures.

Fostering rehydration and facilitating bioactive release through cellulose-assisted leaf surface treatment

Glyphosate is a widely used herbicide in weed control and crop protection. However, its low bioavailability on leaf surfaces of weeds led to excessive use of glyphosate, inducing herbicide-resistant development and major sustainable agricultural and environmental concerns. This study addresses these challenges by developing cellulose-assisted glyphosate formulations using superior rehydration and sustainable release capability of nanocelluloses. We prepared glyphosate-loaded nanocellulose particles (CNP) and cellulose nanofibers (CNF) to enhance the rehydration and sustained release of glyphosate on leaf surfaces. Our results have demonstrated that nanocelluloses significantly improved water capture on the leaf surface and gradual release of glyphosate, with CNP and CNF formulations showing an 8.75-fold increase in water adsorption on cotton leaves compared to the control group over 12 h. Furthermore, incorporating an inorganic salt improved moisture adsorption efficiency. The formulations exhibited high compatibility with existing spray technologies, offering substantial economic and environmental benefits for agriculture practices. This approach highlights the potential application of polysaccharides in revolutionizing agrochemical applications and environmental sustainability, providing great potential in agricultural spraying practices.

Nitrogen and magnesium codoped biochar activates periodate to remediate bensulfuron methyl-contaminated water at low temperature: Performance, mechanisms, and phytotoxicity

Bensulfuron methyl (BSM), a typical sulfonylurea herbicide, has been widely used worldwide for weed suppression and crop protection. Nevertheless, the long-term and prolonged usage led to residues in environment, resulting in the reduction of crop yields and even threatening food security. In this study, the nitrogen/magnesium codoped biochar (NMg-BC) was prepared via two-step pyrolysis method to activate periodate (PI) for BSM degradation. The results demonstrated BSM degradation rate was 87.9 % within 10 min by NMg-BC/PI system at 15 ℃. The system exhibited the favorable tolerance to environmental changes (pH, temperature, anions, and humic acids), presenting high removal efficiency of BSM. Radicals (IO3•) and non-radicals (1O2 and electron transfer) pathways contributed to the degradation of BSM, while the latter performed a crucial role in BSM degradation. Theoretical calculations further confirmed doped of N and Mg changed the electron configuration and electrostatic potential (ESP) distribution of biochar, which was beneficial to provide more active sites for PI activation. Hydroponic experiments showed that NMg-BC/PI system could effectively degrade BSM, and its residue had no significant effect on the length and weight of soybean. The study provides a promising approach for the pollutant remediation in cold regions.

Plant Immunity Modulation in Arbuscular Mycorrhizal Symbiosis and Its Impact on Pathogens and Pests

Arbuscular mycorrhizal (AM) symbiosis is the oldest and most widespread mutualistic association on Earth and involves plants and soil fungi belonging to Glomeromycotina. A complex molecular, cellular, and genetic developmental program enables partner recognition, fungal accommodation in plant tissues, and activation of symbiotic functions such as transfer of phosphorus in exchange for carbohydrates and lipids. AM fungi, as ancient obligate biotrophs, have evolved strategies to circumvent plant defense responses to guarantee an intimate and long-lasting mutualism. They are among those root-associated microorganisms able to boost plants’ ability to cope with biotic stresses leading to mycorrhiza-induced resistance (MIR), which can be effective across diverse hosts and against different attackers. Here, we examine the molecular mechanisms underlying the modulation of plant immunity during colonization by AM fungi and at the onset and display of MIR against belowground and aboveground pests and pathogens. Understanding the MIR efficiency spectrum and its regulation is of great importance to optimizing the biotechnological application of these beneficial microbes for sustainable crop protection.

Identification and knockout of a herbivore susceptibility gene enhances planthopper resistance and increases rice yield.

Brown planthoppers (Nilaparvata lugens) and white-backed planthoppers (Sogatella furcifera) are among the most destructive pests on rice. However, plant susceptibility genes have not yet been exploited for crop protection. Here we identified a leucine-rich repeat protein, OsLRR2, from susceptible rice varieties that facilitates infestation by brown planthopper N. lugens. Field trials showed that knockout of OsLRR2 significantly reduced BPH infestation and enhanced natural biological control by attracting natural enemies. Yield of a susceptible variety was increased by 18% in insecticide-treated plots that eliminated planthoppers and by 25% in untreated plots. These findings underscore the pivotal role of OsLRR2, offering a promising pathway for pest population suppression and rice yield increase.

Nanoparticle LDH enhances RNAi efficiency of dsRNA in piercing-sucking pests by promoting dsRNA stability and transport in plants

Piercing-sucking pests are the most notorious group of pests for global agriculture. RNAi-mediated crop protection by foliar application is a promising approach in field trials. However, the effect of this approach on piercing-sucking pests is far from satisfactory due to the limited uptake and transport of double strand RNA (dsRNA) in plants. Therefore, there is an urgent need for more feasible and biocompatible dsRNA delivery approaches to better control piercing-sucking pests. Here, we report that foliar application of layered double hydroxide (LDH)-loaded dsRNA can effectively disrupt Panonychus citri at multiple developmental stages. MgAl-LDH-dsRNA targeting Chitinase (Chit) gene significantly promoted the RNAi efficiency and then increased the mortality of P. citri nymphs by enhancing dsRNA stability in gut, promoting the adhesion of dsRNA onto leaf surface, facilitating dsRNA internalization into leaf cells, and delivering dsRNA from the stem to the leaf via the vascular system of pomelo plants. Finally, this delivery pathway based on other metal elements such as iron (MgFe-LDH) was also found to significantly improve the protection against P. citri and the nymphs or larvae of Diaphorina citri and Aphis gossypii, two other important piercing-sucking hemipeteran pests, indicating the universality of nanoparticles LDH in promoting the RNAi efficiency and mortality of piercing-sucking pests. Collectively, this study provides insights into the synergistic mechanism for nano-dsRNA systemic translocation in plants, and proposes a potential eco-friendly control strategy for piercing-sucking pests.Graphical

Synthesis and Evaluation of Novel 1-Methyl-1H-pyrazol-5-amine Derivatives with Disulfide Moieties as Potential Antimicrobial Agents.

Sulfur-containing compounds have diverse biological functions and are crucial in crop protection chemistry. In this study, a series of novel 1-methyl-1H-pyrazol-5-amine derivatives incorporating disulfide moieties were synthesized and evaluated for their antimicrobial properties. In vitro bioassays demonstrated that compound 7f displayed potent antifungal activity against Valsa mali, with an EC50 value of 0.64 mg/L, outperforming allicin (EC50 = 26.0 mg/L) but lower than tebuconazole (EC50 = 0.33 mg/L). In vivo experiments confirmed that compound 7f could effectively inhibit V. mali infection on apples at a concentration of 100 mg/L, similar to the positive control tebuconazole. Mechanistic studies revealed that compound 7f could induce hyphal shrinkage and collapse, trigger intracellular reactive oxygen species accumulation, modulate antioxidant enzyme activities, initiate lipid peroxidation, and ultimately cause irreversible oxidative damage to the cells of V. mali. Additionally, compound 7b exhibited notable antibacterial activity, particularly against Pseudomonas syringae pv. actinidiae, with a MIC90 value of 1.56 mg/L, surpassing the positive controls allicin, bismerthiazol, and streptomycin sulfate. These findings suggest that 1-methyl-1H-pyrazol-5-amine derivatives containing disulfide moieties hold promise as potent candidates for the development of novel antimicrobial agents.

Odor Fences Have No Effect on Wild Boar Movement and Home Range Size.

Wild boars are an opportunistic wildlife species that has successfully colonized the human-modified landscape in Europe. However, the current population boom has negative consequences, which result in a rapid increase in human-wildlife conflicts and disease transmission, including African swine fever (ASF). The increasing frequency of conflicts requires adequate solutions for these issues through various measures. Application of deterrents is a common non-lethal measure whose effects have been insufficiently verified until recently. Thus, this study aims to evaluate the effectiveness of odor fences, often applied as a barrier against wild boar movement. For this purpose, 18 wild boars were marked with GPS collars. After 22 days of initial monitoring, 12 sections of odor fences were installed on their home ranges. The monitored wild boars crossed the area 20.5 ± 9.2 times during the pre-installation period and 19.9 ± 8.4 times after the odor fence installation. Moreover, the average home range varied between 377.9 ± 185.0 ha before and 378.1 ± 142.2 ha after the odor fence installation. Based on GPS telemetry results, we do not support using odor repellent lines for crop protection or for limiting wild boar movement to lessen ASF outbreaks.

Roadmap to Success: How Oomycete Plant Pathogens Invade Tissues and Deliver Effectors.

Filamentous plant pathogens threaten global food security and ecosystem resilience. In recent decades, significant strides have been made in deciphering the molecular basis of plant-pathogen interactions, especially the interplay between pathogens' molecular weaponry and hosts' defense machinery. Stemming from interdisciplinary investigations into the infection cell biology of filamentous plant pathogens, recent breakthrough discoveries have provided a new impetus to the field. These advances include the biophysical characterization of a novel invasion mechanism (i.e., naifu invasion) and the unraveling of novel effector secretion routes. On the plant side, progress includes the identification of components of cellular networks involved in the uptake of intracellular effectors. This exciting body of research underscores the pivotal role of logistics management by the pathogen throughout the infection cycle, encompassing the precolonization stages up to tissue invasion. More insight into these logistics opens new avenues for developing environmentally friendly crop protection strategies in an era marked by an imperative to reduce the use of agrochemicals.

Sink strength, nutrient allocation, cannabinoid yield and associated transcript profiles vary in two drug-type Cannabis chemovars.

Cannabis sativa L. is one of the oldest domesticated crops. Hemp-type cultivars, which predominantly produce non-intoxicating cannabidiol (CBD), have been selected for their fast growth, seed, and fibre production, while drug-type chemovars were bred for high accumulation of tetrahydrocannabinol (THC). We investigated how the generation of CBD-dominant chemovars by introgression of hemp- into drug-type Cannabis impacted plant performance. The THC-dominant chemovar showed superior sink strength, higher flower biomass and demand-driven control of nutrient uptake. By contrast, the CBD-dominant chemovar hyperaccumulated phosphate in sink organs leading to reduced carbon and nitrogen assimilation in leaves, which limited flower biomass and cannabinoid yield. RNA-seq analyses determined organ- and chemovar-specific differences in expression of genes associated with nitrate and phosphate homeostasis as well as growth-regulating transcription factors that were correlated with measured traits. Among these were genes positively selected for during Cannabis domestication encoding an inhibitor of the phosphate starvation response SPX DOMAIN GENE3, nitrate reductase and two nitrate transporters. Altered nutrient sensing, acquisition or distribution are likely a consequence of adaption to growth on marginal, low-nutrient input lands in hemp. Our data provide evidence that such ancestral traits may become detrimental for female flower development and consequently overall CBD yield in protected cropping environments.

Exploring Metabolomics to Innovate Management Approaches for Fall Armyworm (Spodoptera frugiperda [J.E. Smith]) Infestation in Maize (Zea mays L.).

The Fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), is a highly destructive lepidopteran pest known for its extensive feeding on maize (Zea mays L.) and other crops, resulting in a substantial reduction in crop yields. Understanding the metabolic response of maize to FAW infestation is essential for effective pest management and crop protection. Metabolomics, a powerful analytical tool, provides insights into the dynamic changes in maize's metabolic profile in response to FAW infestation. This review synthesizes recent advancements in metabolomics research focused on elucidating maize's metabolic responses to FAW and other lepidopteran pests. It discusses the methodologies used in metabolomics studies and highlights significant findings related to the identification of specific metabolites involved in FAW defense mechanisms. Additionally, it explores the roles of various metabolites, including phytohormones, secondary metabolites, and signaling molecules, in mediating plant-FAW interactions. The review also examines potential applications of metabolomics data in developing innovative strategies for integrated pest management and breeding maize cultivars resistant to FAW by identifying key metabolites and associated metabolic pathways involved in plant-FAW interactions. To ensure global food security and maximize the potential of using metabolomics in enhancing maize resistance to FAW infestation, further research integrating metabolomics with other omics techniques and field studies is necessary.

Effect of the insecticide clothianidin on the photosynthetic electron transport chain in pea.

Clothianidin (CL) is a neonicotinoid insecticide widely used in crop protection against insect pests. However, its effects on photosynthesis remain largely unknown. Here, by investigating the influence of CL at the concentrations of 22 and 110 μg/L on the primary processes of photosynthesis, membrane fluidity and structural changes of pea chloroplasts, we located several primary binding sites of this pesticide. Similar dynamics were observed for both concentrations. However, statistically significant differences were only found at 110 μg/L for all methods used. The light saturated rate of linear electron flow decreased mainly due to the disturbance of electron flow on the acceptor side of photosystem II (PSII) associated with the appearance of QB-nonreducing centers and empty QB binding sites of PSII. The functioning of the donor side of PSII, the activity of photosystem I (PSI) and the maximum quantum yield of PSII photochemistry (Fv/Fm) were not found to be significantly altered. Increased membrane fluidity and structural alterations of the thylakoid membrane led to a decrease in the development of the proton gradient ΔрН and membrane energization processes.