Search Results (181)

Ergot, caused by Claviceps purpurea (Fr.) Tul., is a re-emerging disease that is particularly severe under wet weather during cereal flowering. It reduces grain quality and contaminates food and feed with toxic ergot alkaloids. Because no single measure reliably controls it, this study evaluated components of a hybrid protection approach for winter rye, coupling host-based control (cultivar susceptibility) with a panel of chemical, biological and botanical agents assessed in vitro against the pathogen. In a poisoned-medium (agar-dilution) assay, 11 treatments differed highly significantly in the suppression of mycelial growth. Complete inhibition (100%) was obtained with prothioconazole, mandestrobin, a systemic copper formulation, a Bacillus subtilis (QST 713) biocontrol product, mandarin essential oil (EO) (1% and 5%), and lemon and ginger EOs at 5%; azoxystrobin (83.6%) was intermediate, whereas ginger EO at 1% (74.8%) and lemon EO at 1% (30.2%) were significantly less inhibitory, with the EOs showing a clear dose response. In a field trial in which plots were artificially inoculated with a conidial suspension of the pathogen at anthesis, cultivar, location and year all significantly affected ergot content (p < 0.001; model R² = 0.937), which ranged from 0.60% (cultivar DL 19) to 2.69% (cultivar SU Performer). Infestation was governed by a strong location × year interaction, yet a significant cultivar effect was detected within every location and year. Ergot content was very strongly correlated with ergot weight (r = 0.96) but not with yield, indicating that susceptibility was not linearly related to yield in this material and is a cultivar- and environment-driven trait relevant to integrated ergot management. Full article

Pyricularia oryzae Triticum lineage (PoTl), the fungal pathogen responsible for wheat blast disease, has demonstrated increased fitness, stable resistance to quinone outside inhibitor (QoI) fungicides, and no associated fitness cost in the absence of fungicide selection pressure. In this study, we assessed whether the fitness-related epidemiological traits and competitive abilities of QoI-resistant (R) PoTl isolates increased or remained unchanged under continuous QoI applications across multiple disease infection cycles in wheat plants, compared to untreated plants. Approximately 48 h before inoculating each group of QoI-R or sensitive (S) PoTl isolates, wheat plants were treated with 10 μg mL⁻¹ azoxystrobin. The EC₅₀, incubation and latent periods, as well as the germination capacity of the QoI-R isolates inoculated on wheat leaves treated with 10 μg mL⁻¹ azoxystrobin, remained unchanged throughout five successive infection cycles. However, continuous azoxystrobin applications throughout successive disease cycles increased head blast severity by 1.33-fold and conidial production on wheat leaves by 36.8-fold in QoI-resistant (QoI-R) PoTl isolates compared with untreated plants. Conidia germination and germ tube development by QoI-R isolates on the abaxial surface of wheat leaves and/or head rachis treated with 10 μg mL⁻¹ azoxystrobin, six hours after inoculation (h.a.i), were observed using a scanning electron microscope (SEM). These findings demonstrate that repeated azoxystrobin exposure enhances fitness-related epidemiological traits of QoI-R PoTl isolates. Consequently, alternative evolutionarily informed disease management strategies, including fungicide rotation, multisite fungicides, and integrated disease management, are urgently needed. Full article

Tomato leaf mold, caused by Passalora fulva, is one of the most destructive fungal diseases affecting greenhouse tomato production and can cause substantial yield losses under conditions of high relative humidity and moderate temperatures that favor pathogen infection and disease development. This study evaluated the in vitro antifungal activity of a commercial fungicide formulation, Priori Top^® (azoxystrobin + difenoconazole), and three essential oils derived from Eucalyptus globulus, Artemisia herba-alba, and Mentha pulegium against two monoconidial isolates of P. fulva. Unlike previous studies, which have mainly focused on mycelial growth, the present work simultaneously evaluated the effects of the tested products on mycelial growth, sporulation, and conidial germination, providing a comprehensive assessment of antifungal efficacy across three key developmental stages of the pathogen. Antifungal activity was quantified by estimating IC₅₀ and IC₉₀ values using Probit regression analysis. The azoxystrobin–difenoconazole formulation consistently exhibited the highest antifungal activity across all evaluated parameters and showed the lowest estimated IC₅₀ and IC₉₀ values for both fungal isolates. Among the tested essential oils, Artemisia herba-alba exhibited the greatest antifungal activity, reducing mycelial growth by 83% and 78% at 500 ppm for isolates 1 and 2, respectively, and consistently outperforming Mentha pulegium and Eucalyptus globulus. Differences in sensitivity were observed between the two fungal isolates, indicating intraspecific variability in their response to the tested treatments. These findings demonstrate the strong antifungal efficacy of the azoxystrobin–difenoconazole formulation against P. fulva and identify A. herba-alba essential oil as the most promising botanical treatment for integrated management of tomato leaf mold. Further greenhouse and field studies are required to validate these findings, optimize formulation strategies, and evaluate the practical application of A. herba-alba essential oil under commercial production conditions. Full article

The bZIP type transcription factors (bZIPs) are global regulators governing vegetative growth, development, stress defense and secondary metabolism, including mycotoxin production in filamentous fungi. In this work, we constructed and phenotypically characterized gene deletion and complementation mutants of some bZIPs, including Afap1, AflatfA, LziP, AflatfB and bZIP6 in Aspergillus flavus. Environmental and fungicide stress responses, as well as aflatoxin production of the mutants in both surface cultures and infected maize kernels, were studied. Phenotypic characterization of the mutants revealed that Afap1 and AflatfA were involved in the oxidative (H₂O₂, menadione, tert-butyl hydroperoxide), cell wall integrity (Congo Red) and heavy metal (CdCl₂) stress responses of A. flavus. In addition, the Afap1 and AflatfA gene deletions decreased the diamide and prothioconazole tolerances of the fungus, respectively. The ΔLziP strain showed increased growth in the presence of diamide, while reduced colony diameters were observed after exposure to CdCl₂ and fludioxonil. The ΔAflatfB gene deletion mutant was also sensitive to tBOOH, while azoxystrobin and prothioconazole fungicides significantly inhibited the growth of ΔbZIP6. When aflatoxin (AFB1) production was measured in surface cultures, decreased AFB1 levels were detected only in the ΔAflatfA gene deletion mutant strain. However, in corn kernel infection assays, the ΔAfap1, ΔAflatfA, and ΔAflatfB mutants were characterized by significantly reduced aflatoxin production, while the deletion of bZIP6 almost completely abolished AFB1 biosynthesis. Our results suggest that Afap1 and AflatfA appear to be promising targets for the development of new antifungal agents, as their inhibition may increase the sensitivity of A. flavus to environmental stress, simultaneously reducing the aflatoxin production of the fungus and the use of azoles (AflatfA) in the antifungal protection of maize. In addition, bZIP6 may also be considered as an attractive target for further studies when aiming to eliminate aflatoxin production and minimize the use of azoxystrobin and prothioconazole in maize crop protection. Full article

Ginseng Alternaria leaf and stem blight (GALSB), caused by Alternaria alternata, poses a severe threat to ginseng cultivation. Although azoxystrobin is a cornerstone fungicide for GALSB management, the emergence of widespread adaptive resistance has severely curtailed its field efficacy. This study integrated molecular, transcriptomic, and genetic approaches to unravel the underlying resistance mechanisms. Targeted gene sequencing and molecular docking revealed that resistant strains harbor a conserved G143A point mutation in the AaCyt b protein. This mutation weakens the azoxystrobin–AaCyt b protein binding affinity by decreasing the binding energy from −8.31 to −7.08 kcal/mol. Additionally, comparative transcriptomics and RT-qPCR demonstrated pronounced upregulation of the alternative oxidase gene (AaAOX) and core energy metabolism pathways in resistant strain TYC8-2, with AaAOX expression increasing 4.45–6.91-fold. Fungicidal inhibition of AOX via salicylhydroxamic acid (SHAM) restored fungal sensitivity, increasing azoxystrobin sensitivity by 11.66-fold. Crucially, genetic knockout of AaAOX enhanced sensitivity by approximately 2.7 × 10⁴-fold. Phenotypic assays further established AaAOX as a multifunctional regulator; the AaAOX mutant exhibited attenuated virulence on ginseng leaves and increased sensitivity to oxidative and osmotic stresses (NaCl, H₂O₂, NaAc). We conclude that the G143A mutation in AaCyt b and the transcriptional overexpression of AaAOX act independently to drive azoxystrobin resistance in A. alternata. These findings provide comprehensive mechanistic insights to guide resistance monitoring, optimize fungicide applications, and develop precision strategies for GALSB management. Full article

Foxtail millet is one of the important minor cereal crops and is highly valued for its nutritional quality and drought tolerance. With the continuous expansion of the foxtail millet industry, the harm caused by foxtail millet blast has become increasingly severe. In this study, 53 samples of foxtail millet leaves symptomatic of foxtail millet blast were collected from a foxtail millet base in Dingxiang County, Shanxi Province, from June to October 2023. Isolation, culture and identification of the pathogen were carried out, yielding a total of 16 pure isolates, and preliminary studies on the growth inhibition and control effects of the fungus were conducted by determining the plate inhibition rate, scanning electron microscope observations and indoor potted plant experiments. The results showed that based on the morphological characteristics of the isolated strains and the combined analysis of ITS-RPB1-ACT sequences, all 16 pure isolates obtained were identified as Pyricularia oryzae. The results of the antifungal test showed that Bacillus velezensis YQH had the highest inhibition rate of 57.93% against the pathogen of foxtail millet blast; among chemical fungicides, 9% Pyraclostrobin Suspension Concentrate, 45% Prochloraz Emulsifiable Concentrate and 32.5% Difenoconazole–Azoxystrobin Suspension Concentrate had strong inhibitory effects on the fungus, with EC₅₀ values (95% confidence intervals) of 0.328 (0.262–0.400) μg·mL⁻¹, 0.848 (0.578–1.219) μg·mL⁻¹ and 0.310 (0.197–0.484) μg·mL⁻¹, respectively. The results of the potted plant experiment were in accordance with the in vitro antifungal results, and scanning electron microscopy showed that the mycelia in the treatment groups of these three chemical fungicides showed developmental deformities, breakage or surface shrinkage. In conclusion, B. velezensis YQH and the three chemical fungicides (especially 9% Pyraclostrobin Suspension Concentrate and 32.5% Difenoconazole–Azoxystrobin Suspension Concentrate) are effective candidates for controlling foxtail millet blast. Full article

Celosia cristata and Alternanthera philoxeroides both belong to the family Amaranthaceae. Of the two species, C. cristata serves as a medicinal herb as well as an ornamental plant, whereas A. philoxeroides is a notorious invasive weed. In 2024, leaf spot symptoms were observed on C. cristata and A. philoxeroides in Jingzhou City, Hubei Province, China. Based on morphological characteristics and multilocus phylogenetic analysis using sequences of ITS, GAPDH, TEF1, RPB2, and Alt a 1, the pathogen isolated from both hosts was identified as the same species, Alternaria alternantherae. However, differences in morphology were observed between the strains from different hosts. Pathogenicity assays confirmed that this species can cross-infect both host plants. In addition, sensitivities of the pathogen to four fungicides (prochloraz, tebuconazole, azoxystrobin, and carbendazim) were tested in vitro and in vivo. The results revealed that the pathogen was highly sensitive to fungicides prochloraz and tebuconazole. These findings provide valuable insights into the management of leaf spot disease on C. cristata and the development of integrated control strategies for A. philoxeroides. Full article

Tan spot of wheat, caused by the fungus Pyrenophora tritici-repentis (Ptr), is one of the most destructive foliar diseases of wheat worldwide and in Kazakhstan. Expansion of wheat plantings, the adoption of no-till methods, and the use of ineffective fungicides contribute to the accumulation of inoculum and the spread of the pathogen. Despite the important role of fungicides in plant protection, data on the susceptibility of Ptr populations in Kazakhstan are lacking. This study, for the first time, assessed the susceptibility of Ptr isolates from various regions of Kazakhstan to QoI and DMI fungicides. A predominance of genotypes associated with ToxA (82.9%) was found, with a limited distribution of ToxB (7.9%). Propiconazole demonstrated the highest efficacy, inhibiting mycelial growth by an average of 70.85%, followed by pyraclostrobin (69.04%), while azoxystrobin demonstrated lower efficacy (41.47%). Molecular analysis revealed the widespread prevalence of the G143A mutation in the cytochrome b gene, associated with resistance to the QoI fungicide. These results indicate the emergence of strobilurin resistance in Ptr populations in Kazakhstan and highlight the need for regular monitoring of fungicide susceptibility and the development of effective resistance management strategies. Full article

Sugar beet cercospora leaf spot (CLS), caused by the fungus Cercospora beticola, is among the most economically important diseases of sugar beet, and the effectiveness of chemical disease management depends on the susceptibility of pathogen populations to fungicides. In this study, isolates of C. beticola from the Russian Federation were characterized based on QoI resistance, molecular detection of the G143A mutation, and phenotypic variability in radial growth, colony morphology, and aggressiveness. A total of 46 leaf samples were surveyed, and 196 isolates were obtained, from which a representative subset of 48 isolates was selected for detailed analysis. The selected isolates were characterized for in vitro radial growth and colony morphology, assessed for aggressiveness on sugar beet leaves, and tested for sensitivity to azoxystrobin based on EC50 values. The G143A mutation was detected by allele-discriminating real-time PCR and confirmed by sequencing of the cytB region. The G143A mutation was identified in 41 of 48 isolates (85.4%). In the mycelial bioassay, all isolates had EC50 values above 0.2 µg/mL, and 38 of 48 isolates (79.2%) had EC50 values exceeding 100 µg/mL. Additional validation with SHAM in a subset of 35 isolates did not alter the qualitative interpretation of resistance. Considerable variability was also observed in radial growth rate, aggressiveness, and colony appearance among isolates. These findings indicate widespread QoI resistance in the analyzed Russian isolate collection and provide a structured baseline for regional resistance monitoring and for more cautious use of FRAC 11 fungicides in integrated sugar beet disease-management programs. Full article

Impatiens hawkeri W. Bull (I. hawkeri) is popular among consumers due to its diverse flower colors and year-round blooming. However, changes in ecological conditions, cultivation methods, and planting scale have led to increased disease incidence and diversity, particularly the widespread and destructive leaf spot disease. Currently, studies addressing the pathogen species and its biological characteristics remain limited. In this study, a highly pathogenic strain (IH-4) was selected from previously isolated fungi associated with leaf spot in I. hawkeri. Its taxonomic status was confirmed using upright fluorescence microscope analysis, internal transcribed spacer (ITS)/large subunit (LSU)/RNA polymerase II second largest subunit (rpb2)/β-tubulin (tub2) rRNA gene sequencing, and phylogenetic tree construction. Additionally, the biological characteristics of the pathogen and its sensitivity to 8 chemical fungicides were assessed. Strain IH-4 was identified as Ectophoma multirostrata (E. multirostrata) through combined morphological and molecular approaches. Optimal growth conditions included a temperature of 25 °C, a pH of 7, Potato Dextrose Agar (PDA) medium, fructose as the optimal carbon source, and urea as the optimal nitrogen source, with the fastest growth observed under a semi-light photoperiod (12 h light/12 h dark). Fungicide sensitivity assays indicated that 25% azoxystrobin exhibited the lowest half-maximal effective concentration (EC₅₀, 0.0724 μg/mL) and the steepest virulence regression slope (1.7), demonstrating the strongest inhibitory activity and highest sensitivity. Microscopic observations revealed that IH-4 hyphae penetrate I. hawkeri leaf tissues via stomata, colonize internally, and consequently cause host damage. This study provides a theoretical foundation for the timely and effective management of leaf spot disease in I. hawkeri. Full article

Villosiclava virens (anamorph: Ustilaginoidea virens) is a fungal pathogen that causes rice false smut, one of the most devastating diseases of rice. The Uvpks1 gene encoding polyketide synthase is responsible for the biosynthesis of ustilaginoidins, a major group of mycotoxins in V. virens. In this study, three strains, including the Uvpks1 deletion mutant ΔUvpks1, the complementation strain ΔUvpks1-C1, and the wild-type isogenic strain P1 of V. virens, were employed to investigate the role of Uvpks1 in shaping the metabolic profile and in the development, stress responses, and pathogenicity of V. virens. The deletion of Uvpks1 led to both the elimination of ustilaginoidin biosynthesis and the induction of many other secondary metabolite biosynthetic pathways. It decreased mycelial growth and sporulation, fungal tolerance to Congo red-induced cell wall damage stress, and susceptibility to the fungicides epoxiconazole and prochloraz. Meanwhile, it increased hyphal hydrophobicity, resistance to H₂O₂-induced oxidative stress and metal cation stress, and susceptibility to the fungicide azoxystrobin. Furthermore, the deletion of Uvpks1 resulted in reduced fungal pathogenicity toward rice plants. The findings reveal the functions of Uvpks1 in shaping the metabolic profile, development, stress responses, and pathogenicity of V. virens, which will be beneficial for developing new strategies to control rice false smut and ustilaginoidins. Full article

Pesticide use in agriculture can have negative collateral effects on the environment. In this study, two groups of treatments (G1 and G2) based on active substances (ASs) with different mobility were evaluated in order to determine pesticide residues in the soil and their impact on soil microbial populations in two vineyards located in two Denominations of Origin (D.O.). Soil samples were collected in July, October, and the following March over two consecutive years. Pesticide residues were analyzed by liquid chromatography–tandem mass spectrometry (LC-MS/MS) after QuEChERS extraction. Microbial genera were identified by the amplification of the fungal ITS regions with the universal primers ITS86F and ITS4R, and the bacterial 16S rRNA gene (V4 region) with primers 515F and 806R. Although G1 consistently showed higher residues, primarily attributable to azoxystrobin, no significant differences were observed between the two pesticide groups in the total pesticide residues or diversity of microbial communities. The factors D.O., campaign, and sampling month influenced the concentration of residues. Several ASs exhibited different dissipation dynamics depending on the D.O. Azoxystrobin and metrafenone were the most persistent in soil. The LEfSe analysis associated four beneficial fungal genera with the G2 group. The judicious selection of ASs can help to minimize the pesticide residues in soil and their harmful effects on beneficial genera. Full article

Potato black scurf, caused by Rhizoctonia solani, is a widespread soil-borne disease in major potato-producing regions that reduces potato yield and tuber marketability. This study evaluated the field growth-promoting effects and disease-control efficacy of Bacillus velezensis HZ33 on the potato cultivars Xindaping and Longshu 7 and assessed its impact on rhizosphere microbial communities. Field trials showed that the application of HZ33 significantly enhanced potato growth and increased the chlorophyll content, yield, and commercial tuber rates. HZ33 also raised key soil nutrient levels. Its control efficacy against potato black scurf exceeded that of the chemical fungicide azoxystrobin. Application of HZ33 reduced the relative abundance of Rhizoctonia associated with black scurf and increased the relative abundance of beneficial fungi and bacteria. The microbial community structure correlated with both soil chemical properties and the disease index for potato black scurf. Overall, B. velezensis HZ33 appears to be a promising biocontrol agent for suppressing potato black scurf while improving potato yield. Full article

Controlled-release technologies based on natural clays offer a sustainable approach to enhance the efficacy and environmental compatibility of agrochemicals. This study reports the development and evaluation of clay-based azoxystrobin (Az) formulations for controlling Magnaporthiopsis maydis, the causal agent of maize late wilt disease. Among six carriers tested, raw bentonite and sepiolite were selected for their comparable adsorption capacity (9.5% Az loading efficiency) and ease of preparation. A novel mycelial plug-immersion bioassay was established and calibrated (R² = 0.92–0.95) to assess release kinetics and antifungal efficacy, showing approximately tenfold higher sensitivity than conventional disk-diffusion or mycelial-growth inhibition assays. Sequential wash and extended incubation experiments demonstrated sustained Az release equivalent to ≥1 mg L⁻¹ over 144 h, resulting in approximately 50% (p < 0.05) fungal growth suppression. A comparative analysis of particle suspensions and supernatants revealed formulation-specific release behaviors, which differed among clay carriers. Overall, bentonite and sepiolite acted as efficient carriers that prolonged fungicide bioavailability, minimized leaching losses, and preserved biological activity. These findings provide proof of concept for clay–Az formulations as eco-friendly and cost-effective tools for late wilt management and advance understanding of clay–fungicide interactions that support sustainable, integrated disease-control strategies. Full article

The increasing reliance of the European Union on strawberry imports from North African countries, particularly Egypt, underscores the necessity of systematic monitoring of these commodities for pesticide residues prior to their placement on the EU market. This study evaluated pesticide residues in Egyptian strawberries inspected at the Polish border between 2021 and 2024. Detection rates rose sharply from 63% in 2022 to over 90% in 2023–2024, although a subset of samples each year contained no detectable residues (1 sample in 2021 and 2024; 2 in 2022), confirming that pesticide-free production is achievable. Fosetyl-aluminium was the most frequently identified compound, followed by bromide ion, azoxystrobin, and boscalid. Eleven exceedances of maximum residue levels (MRLs) were recorded, involving substances not approved in the EU due to carcinogenic, neurotoxic, or endocrine-disrupting properties. Multiple-residue presence was common, with up to eleven pesticides detected in a single sample. The findings highlight the need for broader surveillance, stricter enforcement, and support for sustainable pest management in exporting countries. Full article