Efficient Fungicide Research Articles

Discovery of Novel Cyclobutyl Oxime Ester Derivatives Containing an α,β-Unsaturated Carbonyl Moiety as Potential Mitochondrial Toxins.

As part of continuous work to explore novel and efficient fungicides originating from natural products, a series of cyclobutyl oxime ester derivatives containing an α,β-unsaturated carbonyl moiety were designed and synthesized. In line with the primary evaluation of the inhibitory effect on common pathogenic fungi causing crop failure, a systematic study on the antifungal activity of target compounds against Rhizoctonia solani was carried out. Most target compounds exhibited satisfactory antifungal activity, and 10 of them were superior to the positive control trifloxystrobin. The most notable median effective concentration (EC50) of compound 6b was 1.70 μg/mL, which was considerable for an intensive study. The control efficacy of compound 6b on potted rice against R. solani was superior to trifloxystrobin at identical concentration. The mycelial morphology and cell membrane permeability of the treated fungi were disrupted, and the meaningful enzyme activities of SDH and POD were also restrained. The reactive oxygen species, nuclear morphology, and mitochondrial membrane potential of the treated hypha reflected an apparent difference compared with the normal morphology, which represented mitochondrial function damage. In addition, chemical features essential for the activity and docking mode within the compound and cytochrome bc1 complex were accessed by computer-aided technology. This study provided insights into the development of new green and efficient fungicides targeting the mitochondria.

Sága, a Deep Learning Spectral Analysis Tool for Fungal Detection in Grains-A Case Study to Detect Fusarium in Winter Wheat.

Fusarium head blight (FHB) is a plant disease caused by various species of the Fusarium fungus. One of the major concerns associated with Fusarium spp. is their ability to produce mycotoxins. Mycotoxin contamination in small grain cereals is a risk to human and animal health and leads to major economic losses. A reliable site-specific precise Fusarium spp. infection early warning model is, therefore, needed to ensure food and feed safety by the early detection of contamination hotspots, enabling effective and efficient fungicide applications, and providing FHB prevention management advice. Such precision farming techniques contribute to environmentally friendly production and sustainable agriculture. This study developed a predictive model, Sága, for on-site FHB detection in wheat using imaging spectroscopy and deep learning. Data were collected from an experimental field in 2021 including (1) an experimental field inoculated with Fusarium spp. (52.5 m × 3 m) and (2) a control field (52.5 m × 3 m) not inoculated with Fusarium spp. and sprayed with fungicides. Imaging spectroscopy data (hyperspectral images) were collected from both the experimental and control fields with the ground truth of Fusarium-infected ear and healthy ear, respectively. Deep learning approaches (pretrained YOLOv5 and DeepMAC on Global Wheat Head Detection (GWHD) dataset) were used to segment wheat ears and XGBoost was used to analyze the hyperspectral information related to the wheat ears and make predictions of Fusarium-infected wheat ear and healthy wheat ear. The results showed that deep learning methods can automatically detect and segment the ears of wheat by applying pretrained models. The predictive model can accurately detect infected areas in a wheat field, achieving mean accuracy and F1 scores exceeding 89%. The proposed model, Sága, could facilitate the early detection of Fusarium spp. to increase the fungicide use efficiency and limit mycotoxin contamination.

Diplodia bulgarica, the cause of canker disease in apple (Malus × domestica) in Türkiye

The cultivated apple (Malus × domestica) is one of Türkiye’s most important economic crops. Over the growing seasons of 2020–2022, typical symptoms of branch cankers and scaling-off of the bark on apple trees were observed in the Eğirdir district of Isparta province. Botryosphaeriaceae fungi were consistently isolated from symptomatic branches. The fungal pathogen was identified as Diplodia bulgarica based on cultural and morphological characteristics and ITS region of DNA sequence data comparisons. Pathogenicity tests were performed on detached shoots by inoculating them with mycelial plugs. Diplodia bulgarica isolates caused necrotic lesions on Scarlet Spur apple detached shoots. To aid in the development of control strategies for this fungus, nine fungicides were examined in vitro for their antifungal effects against the pathogen at different concentrations. Chlorothalonil, tebuconazole, thiophanate-methyl, and fluazinam were the most efficient fungicides, with EC50 values were <1.0 µg/mL.

Application of fungicides in the vegetative stage of soybean [Glycine max (L.) Merrill]: Mini-review

The significant growth of soybean cultivation [Glycine max (L.) Merrill], and the expansion of agriculture throughout Brazil, which occurred during the period of evidence of the industrial policy of import substitution, placed the product as an ideal crop to supply the global demand was growing. Several diseases have already been reported in soybeans, but the incidence and severity depend on some factors, such as climate, cultivars, pathogen inoculum potential, soil structure and fertility, and plant vigor, among others. The disease scenario in soybean crops in Brazil has been changing every year, with an increase in the severity of some diseases, both in the aerial part and those caused by soil-dwelling fungi. The use of resistant cultivars can be adopted and is the most efficient way to control diseases. However, even with adequate management, it is necessary to apply fungicides. For more efficient disease management, it is important to know the effectiveness of the main fungicides used in the crop, in terms of their ability to reduce the progress of the disease in the field; selecting the most efficient fungicides for management. The results of the study demonstrated that fungicides positioned in different application programs reduce the incidence of fungal diseases and improve productivity.

Design, Synthesis and Antifungal Activity of Nootkatone Derivatives Containing Acylhydrazone and Oxime Ester.

In an attempt to search for new natural products-based antifungal agents, fifty-three nootkatone derivatives were designed, synthesized, and evaluated for their antifungal activity against Phytophthora parasitica var nicotianae, Fusarium oxysporum, Fusarium graminearum and Phomopsis sp. by the mycelium growth rate method. Nootkatone derivatives N17 exhibited good inhibitory activity against Phomopsis. sp. with EC50 values of 2.02 μM. The control effect of N17 against Phomopsis. sp. on kiwifruit showed that N17 exhibited a good curative effect in reducing kiwifruit rot at the concentration of 202 μM(100×EC50 ), with the curative effect of 41.11 %, which was better than commercial control of pyrimethanil at the concentration of 13437 μM(100×EC50 ) with the curative effect of 38.65 %. Phomopsis. sp. mycelium treated with N17 showed irregular surface collapse and shrinkage, and the cell membrane crinkled irregularly, vacuoles expanded significantly, mitochondria contracted, and organelles partially swollen by the SEM and TEM detected. Preliminary pharmacological experiments show that N17 exerted antifungal effects by altering release of cellular contents, and altering cell membrane permeability and integrity. The cytotoxicity test demonstrated that N17 showed almost no toxicity to K562 cells. The presented results implied that N17 may be as a potential antifungal agents for developing more efficient fungicides to control Phomopsis sp.

Design, Synthesis, and Antifungal Activity of Some Novel Phenylthiazole Derivatives Containing an Acylhydrazone Moiety.

Crop fungal diseases pose a serious threat to global crop production and quality. Developing new and efficient fungicides is an important measure to control crop diseases. Phenylthiazole was found to be an excellent antifungal skeleton based on our previous study on the structural optimization and biological activity of the natural product thiasporine A. To find new fungicides, 45 phenylthiazole derivatives containing an acylhydrazone moiety were designed and synthesized by the principle of active substructure splicing. Forty-two of the forty-five compounds are novel, except for compounds E1, E14, and E33. Their structures were structurally characterized by 1H NMR, 13C NMR, and HRMS. The antifungal activities of the target compounds against Magnaporthe oryzae Colletotrichum camelliaet, Bipolaris maydis, and Sclerotinia sclerotiorum were evaluated at 25 μg/mL. The bioassay results revealed that most of these compounds exhibited excellent antifungal activities against M. oryzae and C. camelliaet at 25 μg/mL. In particular, compounds E4, E10, E14, E17, E23, E26, and E27 showed the inhibition rate of more than 80% against M. oryzae, with EC50 values of 1.66, 2.01, 2.26, 1.45, 1.50, 1.29, and 2.65 μg/mL, respectively, which were superior to that of the commercial fungicides Isoprothiolane (EC50 = 3.22 μg/mL) and Phenazine-1-carboxylic acid (EC50 = 27.87 μg/mL). The preliminary structure-activity relationship (SAR) results suggested that introducing methyl, halogen, or methoxy at the ortho-position of R1 and the para-position of R2 can endow the final structure with excellent antifungal activity against M. oryzae. The current results provide useful data for developing phenylthiazole derivatives as new fungicides for controlling rice blast caused by M. oryzae.

Fungicidal Activity of Novel Quinazolin-6-ylcarboxylates and Mode of Action on Botrytis cinerea.

Fungal diseases remain important causes of crop failure and economic losses. As the resistance toward current selective fungicides becomes increasingly problematic, it is necessary to develop efficient fungicides with novel chemotypes. A series of novel quinazolin-6-ylcarboxylates which combined the structures of pyridine or heterocyclic motif and the N-(3-chloro-4-fluorophenyl)quinazolin-4-amine moiety, a binding group of ATP-binding site of gefitinib, were evaluated for their fungicidal activity on different phytopathogenic fungi. Most of these compounds showed excellent fungicidal activities against Botrytis cinerea and Exserohilum rostratum, especially compound F17 displayed the highest activity with EC50 values as 3.79 μg/mL against B. cinerea and 2.90 μg/mL against E. rostratum, which was similar to or even better than those of the commercial fungicides, such as pyraclostrobin (EC50 , 3.68, 17.38 μg/mL) and hymexazol (EC50 , 4.56, 2.13 μg/mL). Moreover, compound F17 significantly arrested the lesion expansion of B. cinerea infection on tomato detached leaves and strongly suppressed grey mold disease on tomato seedlings in greenhouse. The abilities of compound F17 to induce cell apoptosis of the non-germinated spores, to limit oxalic acid production, to reduce malate dehydrogenase (MDH) expression, and to block the active pocket of MDH protein were demonstrated in B. cinerea. The novel quinazolin-6-ylcarboxylates containing ATP-binding site-directed moiety, especially compound F17, could be developed as a potential fungicidal candidate for further study. This article is protected by copyright. All rights reserved.

Methods for Fungicide Efficacy Screenings: Multiwell Testing Procedures for the Oomycetes Phytophthora infestans and Pythium ultimum.

Oomycetes-borne diseases represent a serious problem for agriculture sustainability due to the high use of chemical products employed for their control. In recent years, increasing concerns on side effects associated with fungicide utilization have led to the reduction of the permissible modes of action, with the remaining ones continuously threatened by the increase of resistant strains in the pathogen populations. In this context, it is mandatory to develop new generation fungicides characterized by high specificity towards the target species and low environmental impact to guarantee the sustainability, productivity, and quality of food production. Fungicide discovery is a lengthy and costly process, and despite these urgent needs, poor description and formalization of high-throughput methodologies for screening the efficacy of active compounds are commonly reported for these kinds of organisms. In this study, a comprehensive picture of two high-throughput practices for efficient fungicide screening against plant-pathogenic oomycetes has been provided. Different protocols using multiwell plates were validated on approved crop protection products using Phytophthora infestans and Pythium ultimum as the model species. In addition, detailed statistical inputs useful for the analysis of data related to the efficacy of screenings are included.

Baseline sensitivity of Coniella vitis to fluazinam and resistance risk assessment

AbstractGrape white rot is a destructive fungal disease caused by the pathogenic fungus Coniella vitis. The sensitivity of C. vitis to fluazinam was tested to select an efficient fungicide to control this disease. Furthermore, the baseline sensitivity of C. vitis populations to fluazinam was established based on the EC50 of 62 C. vitis strains collected from different regions in which grapevines are grown in China. The C. vitis populations were extremely sensitive to fluazinam. The efficiency of fluazinam to grape white rot was determined with detached grapevine leaves. Fluazinam was highly effective in controlling this disease. Moreover, the risk of the C. vitis strains developing resistance to fluazinam was assessed with five mutant strains resistant to fluazinam obtained by a fungicide selection method in the laboratory. The fluazinam‐resistant mutant strains were deficient in their hyphal growth, stress and virulence compared with the parental strain. This led to the conclusion that the C. vitis populations are highly sensitive to fluazinam, and C. vitis is unlikely to develop resistance to fluazinam under natural conditions. Thus, fluazinam is a potential fungicide to efficiently control grape white rot.

Cucumber target spot control and Corynespora cassiicola inhibition by uni-and multi-site fungicides

Target spot, caused by Corynespora cassiicola, is among the main disease that may reduce cucumber yield in worldwide. However, few target spot control strategies have been evaluated. The study aimed to evaluate the effect of fungicides in controlling C. cassiicola in vitro and cucumber target spot in a greenhouse. The effect of seven and thirteen fungicides in conidial germination and mycelial growth, respectively, of three pathogen isolates was evaluated in culture medium. The most efficient fungicides in vitro were applied on cucumber plants, at the recommended commercial dose. After three or seven days of the preventive treatment, plants were sprayed with suspensions of the pathogen (104 conidia/mL). For the curative treatment, plants were inoculated 24 h before receiving the fungicide. Evaluation included target spot severity, number and diameter of lesions and sporulation on the leaf. Fungicides of the groups Methyl Benzimidazole Carbamates (MBC) and Quinone outside Inhibitors (QoI) were inefficient (EC50 > 100 μg/mL) in inhibiting the pathogen in vitro. Chlorothalonil, metiram, boscalid, difenoconazole, epoxiconazole, tebuconazole, and flutriafol showed EC50 < 1 or 1–10 μg/mL. Chlorothalonil, metiram + pyraclostrobin, boscalid + kresoxim-methyl, and azoxystrobin + benzovindiflupyr controlled the disease, providing greater severity reduction as preventive treatment, without any difference between the two application times. The number and diameter of lesions decreased when fungicides were applied as preventive treatment. Chlorothalonil reduced the number of lesions in curative treatment, while fluxapyroxad + pyraclostrobin, azoxystrobin + benzovindiflupyr, boscalid + kresoxim-methyl, and difenoconazole decreased the diameter of lesions. Sporulation on the leaves also reduced, especially when fungicides were preventively employed. A preventive management is recommended in areas with frequent reports of target spot outbreaks, adopting the alternation of the four most efficient fungicides in controlling the disease in order to reduce possible emergence of resistant isolates of the pathogen to the site-specific fungicides boscalid and benzovindiflupyr.

Discovery of Novel Quinazoline-2-Aminothiazole Hybrids Containing a 4-Piperidinylamide Linker as Potential Fungicides against the Phytopathogenic Fungus Rhizoctonia solani.

A total of 29 novel quinazoline-2-aminothiazole hybrids containing a 4-piperidinylamide linker were designed, synthesized, and evaluated for their anti-microbial properties against phytopathogenic fungi and bacteria of agricultural importance. The anti-fungal assays indicated that some of the target compounds exhibited excellent inhibitory effects in vitro against Rhizoctonia solani. For example, 11 compounds within this series (including 4a, 4g, 4h, 4j, 4o, 4s, 4t, 4u, 4v, 4y, and 4b') were found to possess EC50 values (effective concentration for 50% activity) ranging from 0.42 to 2.05 μg/mL against this pathogen. In particular, compound 4y with a 2-chloro-6-fluorophenyl substituent displayed a potent anti-R. solani efficacy with EC50 = 0.42 μg/mL, nearly threefold more effective than the commercialized fungicide Chlorothalonil (EC50 = 1.20 μg/mL) and also slightly superior to the other fungicide Carbendazim (EC50 = 0.53 μg/mL). Moreover, compound 4y could efficiently inhibit the growth of R. solani in vivo on the potted rice plants, displaying an impressive protection efficacy of 82.3% at 200 μg/mL, better than those of the fungicides Carbendazim (69.8%) and Chlorothalonil (48.9%). Finally, the mechanistic studies showed that compound 4y exerted its anti-fungal effects by altering the mycelial morphology, increasing the cell membrane permeability, and destroying the cell membrane integrity. On the other hand, some compounds demonstrated good anti-bacterial effects in vitro against Xanthomonas oryzae pv. oryzae (Xoo). Overall, the presented results implied that 4-piperidinylamide-bridged quinazoline-2-aminothiazole hybrids held the promise of acting as lead compounds for developing more efficient fungicides to control R. solani.

Effects of soil treated fungicide fluopimomide on tomato (Solanum lycopersicum L.) disease control and plant growth.

Fluopimomide is a novel acid amide fungicide registered for the control of many plant pathogens. In the present study, the effects of soil-treated fluopimomide on soil micro biomass, disease incidence, plant growth, soil enzyme activity, and marketable yield of tomato (Solanum lycopersicum L.) were investigated via field trial. In addition, the application prospect in China was also evaluated. In the experiment, five treatments with three replications and a randomized complete block design were followed. The treatments were: furrow application of fluopimomide (25% suspension concentrate, SC) at the dosage of 375, 750, and 1,500 g ha−1, which was recommended, double recommended, and quadruple recommended dosages, respectively. Besides, common control fungicide fluopicolide (5% SC) furrow was applied at recommended application dosages of 750 mL ha−1, and a non-treated control was also undertaken. Results indicated that fluopimomide exhibited no effects on the amount of soil bacteria and actinomycetes, and its inhibition effect on fungi amount could be recovered at 60 days after treatment (DAT). With the recommended application dosage, fluopimomide could efficiently reduce the number of plant pathogens in soil by 79.56–85.80%, significantly reduce the disease incidences in tomato plants by 80.00–88.24%, and improve plant height by 13.25–24.05% and marketable yield by 16.88%. Furthermore, soil enzymes exhibited a complex response to fluopimomide, and AOB and nifH gene copy numbers were increased by the double and quadruple recommended dosage of fluopimomide. Based on the above results, fluopimomide could be recommended as an efficient fungicide for the tomato field.

Particularities of Fungicides and Factors Affecting Their Fate and Removal Efficacy: A Review

Systemic fungicide use has increased over the last decades, despite the susceptibility of resistance development and the side effects to human health and the environment. Although herbicides and insecticides are detected more frequently in environmental samples, there are many fungicides that have the ability to enter water bodies due to their physicochemical properties and their increasing use. Key factors affecting fungicide fate in the environment have been discussed, including the non-target effects of fungicides. For instance, fungicides are associated with the steep decline in bumblebee populations. Secondary actions of certain fungicides on plants have also been reported recently. In addition, the use of alternative eco-friendly disease management approaches has been described. Constructed Wetlands (CWs) comprise an environmentally friendly, low cost, and efficient fungicide remediation technique. Fungicide removal within CWs is dependent on plant uptake and metabolism, absorption in porous media and soil, hydrolysis, photodegradation, and biodegradation. Factors related to the efficacy of CWs on the removal of fungicides, such as the type of CW, plant species, and the physicochemical parameters of fungicides, are also discussed in this paper. There are low-environmental-risk fungicides, phytohormones and other compounds, which could improve the removal performance of CW vegetation. In addition, specific parameters such as the multiple modes of action of fungicides, side effects on substrate microbial communities and endophytes, and plant physiological response were also studied. Prospects and challenges for future research are suggested under the prism of reducing the risk related to fungicides and enhancing CW performance.

ANTIFUNGAL ACTIVITY OF SELECTED CHEMICAL AGENTS AGAINST PHYTOPATHOGENIC ISOLATED FUNGI SPORES.

Postharvest deterioration has been a major problem associated with yam storage for both famers and traders and it is caused mostly by micro-organisms especially fungi. During the storage of yam, many organisms such as Aspergillus flavus, Aspergillus niger, Penicillium citrinum and Rhizopus stolonifer are often reported to cause rotting of the stored yams. The aim of this research is to find out the antifungal effect of some commonly used anti-dermatophytic agents,(Fluconazole, Terbinafine Hcl, Ketoconazole, Sodium propionate and Griseofulvin) on the above named isolated fungi spores. This was carried out using zone of inhibition, MICs, MFCs, FICs and FFCs to measure the antifungal activities of the test antifungal agents against the isolated phytopathogenic fungi spores. These agents were found to have fungitoxic effects on the test organisms in the order of: Terbinafine Hcl &gt; Fluconazole &gt; Ketoconazole &gt; Sodium propionate &gt; Griseofulvin. This work indicated that the test antifungal agents were able to inhibit the fungi spores that are widely reported to be associated with yams rot when stored. The observation in this study showed that a good and efficient fungicide against the test organisms that are known to cause yam rot during storage can be effectively arrested with combination of these fungicides.

Design, synthesis, and fungicidal activity of novel N‐substituted piperazine‐containing phenylpyridines against cucumber downy mildew

Cucumber downy mildew (CDM) is a severe plant disease and affects the yield of cucumber production worldwide. As the resistance toward conventional fungicides is emerging as a ubiquitous issue, it is urgent to discover efficient fungicides with unique structures. In this study, a series of novel phenylpyridine derivatives were designed and synthesized. Bioassays revealed that most of these compounds possessed excellent fungicidal activities against CDM. Among the phenylpyridine compounds, 2-(4-(4-(tert-butyl)benzyl)piperazin-1-yl)-6-phenylnicotinonitrile (C8) [half-maximal effective concentration (EC50 ) = 4.40 mg L-1 ] displayed the highest activity, which was better than those of the commercial fungicides, such as azoxystrobin (EC50 =42.77 mg L-1 ) and flumorph (EC50 =41.94 mg L-1 ). Furthermore, the molecular electrostatic potential of high-activity compound C8 indicated that nitrogen atom of the cyano group on the pyridine ring was in the negative region and may easily form hydrogen bonds and allow for electrostatic interactions with potential receptors. This study demonstrated that the novel N-substituted piperazine-containing phenylpyridine derivatives could be further developed as a candidate compound to control CDM.

Potential Antagonistic Bacteria against Verticillium dahliae Isolated from Artificially Infested Nursery

As an ecofriendly biocontrol agent, antagonistic bacteria are a crucial class of highly efficient fungicides in the field against Verticillium dahliae, the most virulent pathogen for cotton and other crops. Toward identifying urgently needed bacterial candidates, we screened bacteria isolated from the cotton rhizosphere soil for antagonisitic activity against V. dahliae in an artificially infested nursery. In preliminary tests of antagonistic candidates to characterize the mechanism of action of on culture medium, 88 strains that mainly belonged to Bacillus strongly inhibited the colony diameter of V. dahliae, with inhibiting efficacy up to 50% in 9 strains. Among the most-effective bacterial strains, Bacillus sp. ABLF-18, and ABLF-50 and Paenibacillus sp. ABLF-90 significantly reduced the disease index and fungal biomass of cotton to 40–70% that of the control. In further tests to elucidate the biocontrol mechanism (s), the strains secreted extracellular enzymes cellulase, glucanase, and protease, which can degrade the mycelium, and antimicrobial lipopeptides such as surfactin and iturin homologues. The expression of PAL, MAPK and PR10, genes related to disease resistance, was also elicited in cotton plants. Our results clearly show that three candidate bacterial strains can enhance cotton defense responses against V. dahliae; the secretion of fungal cell-wall-degrading enzymes, synthesis of nonribosomal antimicrobial peptides and induction of systemic resistance shows that the strains have great potential as biocontrol fungicides.

Fenhexamid - an efficient and inexpensive fungicide for selection of Magnaporthe oryzae transformants

Magnaporthe oryzae is one of the most economically important phytopathogenic fungi, and is used as a model organism to study plant-pathogen interactions. To unravel the infection process, forward and reverse genetic approaches are essential, but are often hindered by the lack of a straightforward selection procedure for transformants. Here we report on the use of fenhexamid, an inhibitor of ergosterol biosynthesis, for selection of M. oryzae transformants. An allele of the sterol 3-ketoreductase gene of Fusarium fujikuroi (FfERG27), known to confer resistance to fenhexamid, has already been used successfully with transformants of Botrytis cinerea. Our results demonstrate that expression of the FfERG27 allele in M. oryzae also enables highly efficient selection of transformants on fenhexamid-containing media. The use of fenhexamid is an inexpensive alternative for selection as compared to commonly used antibiotics like hygromycin. No impact on growth and infection phenotypes of fenhexamid resistant M. oryzae mutants was detected, which underpins its usefulness for selecting M. oryzae transformants.

Peanut disease epidemiology under dynamic microclimate conditions and management practices in North Florida.

Diverse field characteristics, weather patterns, and management practices can result in variable microclimates. The objective was to relate in-field microclimate conditions with peanut diseases and yield and determine the effect of irrigation and fungicides within these environments. Irrigation did not have a major impact on disease and yield. Stem rot (Athelia rolfsii) and early (Passalora arachidicola) and late (Nothopassalora personata) leaf spot were most affected by changes in environmental patterns across seasons. Average non-treated stem rot was 12.9% in 2017 which dropped considerably in 2018 to 0.2% but emerged again in 2019 to 3.2%. Stem rot incidence varied across the field, and the response to fungicides depended on management zone. Leaf spot defoliation in non-treated plots was severe in 2019 reaching an average of 73% at 126 days after planting but only reached 15% in 2017 and 35% in 2019 at the same stage. A low-input fungicide schedule was able to reduce foliar disease in all zones and seasons, but the microclimatic conditions in the low-lying area favored leaf spot in 2017 and 2018 although not in the dryer 2019 season. Seasonal differences in disease and plant growth affected the level of protection against average yield loss using a standard low-input program which in 2017 (527 kg/ha) was not as great as 2018 (2,235 kg/ha) or 2019 (1,763 kg/ha). Disease prediction models built on dynamic environmental factors in the context of multiple pathogens and natural field conditions could be developed to improve within-season management decisions for more efficient fungicide inputs.

Synthesis and fungicidal activity of novel benzimidazole derivatives bearing pyrimidine-thioether moiety against Botrytis cinerea.

Botrytis cinerea is a serious plant fungus and strongly affects the yield and quality of crops. The main control strategy is the employment of fungicides. To research for efficient fungicide with novel structure, a series of novel benzimidazole derivatives bearing pyrimidine and thioether moieties were designed and synthesized. Some target compounds such as 4h, 4i, 4k, 4l, 4m, 4s, 4t and 4u exhibited notable fungicidal activities, with half maximal effective concentration (EC50 ) values in the range 0.13-0.24 μg mL-1 , which means that their activities were comparable or higher than that of carbendazim (EC50 = 0.21 μg mL-1 ). Among them, N-(4-fluorophenyl)-2-((4-(1H-benzimidazol-2-yl)-6-(4-methoxyphenyl) pyrimidin-2-yl)thio)acetamide (4m) displayed the best activity (EC50 = 0.13 μg mL-1 ). Molecular electrostatic potential analysis of 4m elucidated that the NH moiety of benzimidazole ring was located in the positive potential region and may generate hydrogen bond with target amino acid residue. Molecular docking analysis revealed that there was one hydrogen bond and one 𝜋-𝜋 interaction between 4m and target protein. This study demonstrated that the benzimidazole derivatives bearing pyrimidine and thioether moieties can be further optimized as a lead compound for the control of B. cinerea. The combination of molecular electrostatic potential and molecular docking analyses may provide a valuable reference for studying the interaction between the ligand and target protein. © 2021 Society of Chemical Industry.

Development of a PacBio Long-Read Sequencing Assay for High Throughput Detection of Fungicide Resistance in Zymoseptoria tritici.

Fungicide resistance has become a challenging problem in management of Septoria tritici blotch (STB), caused by Zymoseptoria tritici, the most destructive disease of winter wheat throughout western and northern Europe. To ensure the continued effectiveness of those fungicides currently used, it is essential to monitor the development and spread of such resistance in field populations of the pathogen. Since resistance to the key families of fungicides used for STB control (demethyalation inhibitors or azoles, succinate dehydrogenase inhibitors or SDHIs and Quinone outside Inhibitors or QoIs) is conferred through target-site mutations, the potential exists to monitor resistance through the molecular detection of alterations in the target site genes. As more efficient fungicides were developed and applied, the pathogen has continuously adapted through accumulating multiple target-site alterations. In order to accurately monitor these changes in field populations, it is therefore becoming increasingly important to completely sequence the targeted genes. Here we report the development of a PacBio assay that facilitates the multiplex amplification and long-read sequencing of the target gene(s) for the azole (CYP51), SDHI (Sdh B, C, and D), and QoI (cytochrome b) fungicides. The assay was developed and optimised using three Irish Z. tritici collections established in spring 2017, which capture the range of fungicide resistance present in modern European populations of Z. tritici. The sequences obtained through the PacBio assay were validated using traditional Sanger sequencing and in vitro sensitivity screenings. To further exploit the long-read and high throughput potential of PacBio sequencing, an additional nine housekeeping genes (act, BTUB, cal, cyp, EF1, GAPDH, hsp80-1, PKC, TFC1) were sequenced and used to provide comprehensive Z. tritici strain genotyping.