Fungicides Thiophanate-methyl Research Articles

Targeted discovery of unusual diterpenoids with anti-fungal activity from the root of Euphorbia lathyris

Lathyrisone A (1), a diterpene with an undescribed tricyclic 6/6/6 fused carbon skeleton, along with spirolathyrisins B-D (3–5), three diterpenes with a rare [4.5.0] spirocyclic carbon skeleton, and one known compound (2) were isolated from the roots of Euphorbia lathyris. Their chemical structures were characterized by extensive spectroscopic analysis, X-ray crystallography, ECD and quantum chemistry calculation. A plausible biosynthetic pathway for compounds 1–5 was proposed, which suggested it is a competitive pathway for ingenol biosynthesis in the plant. The anti-fungal activities of these compounds were tested, especially, compound 2 showed stronger anti-fungal activities against Fusarium oxysporum and Alternaria alternata than the positive control fungicide thiophanate-methyl. The preliminary structure–activity relationship of compounds 1–5 was also discussed. These results not only expanded the chemical diversities of E. lathyris, but also provided a lead compound for the control of plant pathogens.

CRISPR-enabled investigation of fitness costs associated with the E198A mutation in β-tubulin of Colletotrichum siamense.

Understanding fitness costs associated with fungicide resistance is critical to improve resistance management strategies. E198A in b-tubulin confers resistance to the fungicide thiophanate-methyl and has been widely reported in several plant pathogens including Colletotrichum siamense. To better understand potential fitness costs associated with the resistance, a ribonucleoprotein (RNP) complex mediated CRISPR/Cas9 system was used to create a point mutation (E198A) through homology directed repair (HDR) in each of the sensitive (E198) C. siamense isolates collected from strawberries, raspberries, and peaches. The RNP complex was delivered into fungal protoplasts using polyethylene glycol-mediated (PEG) transfection. The transformation efficiency, the proportion of transformants of sensitive parental isolates containing the E198A mutation, averaged 72%. No off-target mutations were observed when sequences similar to the b-tubulin target region with a maximum of four mismatch sites were analyzed, suggesting that the CRISPR/Cas9 system used in this study was highly specific for genome editing in C. siamense. Of the 41 comparisons of fitness between mutant and wild type isolates through in vitro and detached fruit assays, mutant isolates appeared to be as fit (24 of 41 comparisons), if not more fit than wild-type isolates (10 of 41 comparisons). The use of CRISPR/Cas9 to evaluate fitness costs associated with point mutations in this study represents a novel and useful method, since wild-type and mutant isolates were genetically identical except for the target mutation.

Advanced technology for photocatalytic degradation of thiophanate-methyl: Degradation pathways, DFT calculations and embryotoxic potential

This study focuses on establishing an efficient two-step technology, which includes: (1) consecutive adsorption-desorption, using cellulose-based membranes, bCells, and (2) photocatalytic degradation of the fungicide thiophanate-methyl (TPM), using synthesized Ag-P25 and Ce-P25 catalysts. The catalysts, obtained by controlled deposition of Ag2O/Ag and CeO2 onto P25 TiO2 carrier (Degussa), were characterized using ATR-FTIR, XRPD, BET, FESEM, HRTEM, HAADF-EDS and UV–DRS techniques. In order to establish a feasible purification technology, preconcentration of TPM was performed by adsorption, achieving 75.5 and 92.9 mg/g of TPM removal using bCell-EpL and bCell–EpL–TA membranes, respectively, followed by efficient desorption (> 95%) that provided acceptable TPM concentration for photodegradation experiments. Under optimal conditions (0.07 g/L of both catalysts), complete degradation of TPM (5 mg/L) occurred within 2 h, compared to 4 h for the base TiO2 P25. Measurements of quantum yield and the results of HPLC-MS analysis, alongside DFT calculation, assisted in understanding the TPM degradation pathways. New degradation products were detected and proposed from HPLC–MS analysis. Embryotoxic assays, performed on zebrafish (Danio rerio), applied to estimate the toxicity evolution of time-dependent generated TPM degradation products, showed low embryotoxic potential. Chemical oxygen demand (26 mg O2/L) confirmed low ecotoxicological pressure of effluent water.

Specific detection of fungicide thiophanate-methyl: A smartphone colorimetric sensor based on target-regulated oxidase-like activity of copper-doped carbon nanozyme

Nanozyme-based colorimetric assays have shown great potential in the rapid and sensitive determination of pesticide residue in environment. However, the non-specific enzyme inhibition makes the assays generally lack of selectivity. In this study, we proposed a colorimetric sensing platform for the specific detection of the agricultural fungicide thiophanate-methyl (TM) based on its distinctive inhibitory effect on the nanozyme activity. Since TM contains the symmetric ethylenediamine- and bisthiourea-like groups, it displays strong affinity to the metal site, leading to a loss of the catalytic activity. Accordingly, a Cu-doped carbon nanozyme with excellent oxidase-like properties was designed, and the oxidation process of chromogenic substrate is promoted by Cu-induced generation of reactive oxygen species. Interestingly, the nanozyme activity can be directly and strongly restrained by TM, rather than other probably coexistent pesticides. Consequently, the as-proposed analytical method exhibits specific response toward TM and good linear relationship in the range of 0.2–15 μg mL−1 with a low limit of detection of 0.04 μg mL−1 (S/N = 3). Besides, a smartphone-assisted rapid detection was achieved through identifying the RGB value of the chromogenic system. This work provides a new nanozyme inhibition strategy for the specific detection of TM in environmental sample.

Risk assessment of predatory lady beetle Propylea japonica's multi-generational exposure to three non-insecticidal agrochemicals

The effects of non-insecticidal agrochemicals on pest natural predators remain largely unexplored except bees and silkworm. The herbicide quizalofop-p-ethyl (QpE), fungicide thiophanate-methyl (TM), and plant growth regulator mepiquat chloride (MC) have been extensively applied as non-insecticidal agrochemicals. Here, we systematically evaluated multiple effects of these 3 non-insecticidal agrochemicals on three generations of Propylea japonica, an important agroforestry predatory beetle, including the effects on its development, reproduction, enterobacteria, and transcriptomic response. The results showed that QpE exhibited a hormetic effect on P. japonica, thus significantly increasing the survival rate of generation 2 (F2) females, generation 3 (F3) females, and F3 males and body weight of F3 males. However, three successive generations exposed to TM and MC had no significant effect on longevity, body weight, survival rate, pre-oviposition period, and fecundity of P. japonica. Additionally, we investigated the effects of MC, TM, and QpE exposure on gene expression and gut bacterial community of F3 P. japonica. Under MC, TM, and QpE exposure, the overwhelming genes of P. japonica (99.90 %, 99.45 %, and 99.7 %) remained unaffected, respectively. Under TM and MC exposure, differentially expressed genes (DEGs) were not significantly enriched in any KEGG pathway, indicating TM and MC did not significantly affect functions of P. japonica, but under QpE exposure, the expression levels of drug metabolism-related genes were down-regulated. Although QpE treatment did not affect gut dominant bacterial community composition, it significantly increased relative abundances of detoxification metabolism-related bacteria such as Wolbachia, Pseudomonas and Burkholderia in P. japonica. However, TM and MC had no significant effect on the gut bacterial community composition and relative abundance in P. japonica. This study revealed for the first time the mechanism by which P. japonica might compensate for gene downregulation-induced detoxification metabolism decline through altering symbiotic bacteria under QpE exposure. Our findings provide reference for the rational application of non-insecticidal agrochemicals.

Antifungal activities of aqueous extracts of moroccan medicinal plants against Monilinia spp. agent of brown rot disease

Apple fruit is one of the worldwide most industrially valuable horticulture crops. However, the fruit is vulnerable to post-harvest brown rot degradation caused by Monilinia laxa and Monilinia fructigena, which is a prominent pre-and post-harvest disease of tree fruit. Numerous non-chemical post-harvest treatments have been investigated so far to control these pathogens to provide an alternative option to the synthetic fungicides that are commonly used and may have negative effects on human health and the environment. Therefore, this study aimed to assess the in vitro and in vivo efficacy at different concentrations of nine plants' aqueous extracts from Mentha pulegium, Citrus aurantium, Thymus vulgaris, Origanum compactum, Lavandula angustifolia, Syzygium aromaticum, Rosmarinus officinalis, Citrus sinensis and Eucalyptus radiate against the development of brown rot. The results demonstrated significant antifungal activities of all tested aqueous extracts on both fungi compared to the thiophanate-methyl fungicide (1 ppm) (100% inhibition). At the concentration of 1.5 mg/ml, S. aromaticum and O. compactum extracts were the most effective, showing significant inhibition values against M. laxa (91.06%) and against M. fructigena (90.02%). Interestingly, at higher concentration, spore germination of both Monilinia strains was significantly reduced with inhibition rate of 98.64% for M. laxa and 93.04% for M. fructigena. Also, high flavonoids and polyphenols contents were shown. Aqueous extracts of O. compactum, S. aromaticum, and T. vulgaris reduced the brown rot severity and incidence in vivo. The application of these plants' aqueous extracts on fruits seems to have a significant effect on fruit quality persistence, as indicated by weight loss, fruit firmness, total soluble solids, titrable acidity, and maturity index during 15 days of storage at 4 °C. The spectra analyzed from all tested plants revealed typical peaks and a large variety of functional groups such as C–H bonds, O–H groups, and C–C stretching. The plant’s aqueous extracts studied can be used as bio-fungicides against brown rot diseases.

Designing Starch–Alginate Hydrogels for Controlled Delivery of Fungicide for the Alleviation of Environmental Pollution

In this work, a controlled delivery system for the fungicide thiophanate-methyl (TM) was developed for the alleviation of environmental pollution using starch–alginate–polyacrylamide hydrogels as a sustainable agricultural development approach. The polymer hydrogel was synthesized by grafting poly(acrylamide) onto starch–alginate using N,N-methylenebisacrylamide (NNMBA) as the cross-linker. The copolymers were confirmed by characterization techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared analysis, X-ray diffraction, 13C NMR, TGA-DTG, and differential scanning calorimetry. SEM confirmed the heterogeneity, and AFM showed the rough surface morphology of the copolymeric hydrogels. The thermogravimetric analysis results indicated the increase in the thermal stability of the cross-linked polymers after modification. Evaluation was carried out on the water absorption capacity of the polymer and the release of the encapsulated fungicide. The swelling of the hydrogel decreased with the increment in cross-linking density with a rise in [NNMBA]. It also influenced the diffusion of the fungicide from the encapsulated copolymer, wherein the increase in the cross-linker content decreased the fungicide release from the copolymer. Hydrogels absorbed 18.30 ± 1.40 (g/g of gel) water, indicating the water retention capacity of the hydrogel material which could be useful for plant growth in the arid regions. The release profile followed the non-Fickian diffusion mechanism with a sustained delivery of TM. Water retention and the controlled release properties of the hydrogel indicated its usefulness in sustainable agricultural development and alleviation of environmental pollution caused by the fungicide use. Overall, the formation of a controlled pesticide delivery system based on natural polysaccharides with polyacrylamide-based hydrogels which act as nutrients for plants on degradation is a unique approach, implying that the slow release of the pesticide will reduce environmental pollution and pesticide cost.

EFFECTS OF POMEGRANATE JUICE CONSUMPTION ON THE FERTILITY AND PROTECTIVE ACTIVITY AGAINST A FUNGICIDE EXPOSURE IN MALE WISTAR RATS

Introduction: The aim of this study is to throw light on the possible protective effect of pomegranate juice (GJ) (Punica granatum L) after experimental oral administration of fungicide Thiophanate Methyl (TM) and its effects on sperm quality, of male healthy Wistar rats.
 Materials and Methods: Fifteen healthy adult male Wistar rats were divided into 03 groups. Group 1: control, Group 2: treated with Thiophanate Methyl (TM) (150 mg / kg) and Group 3: Treated with Thiophanate Methyl + pomegranate juice (GJ) (150 mg/kg + 1.5 ml). The method used for the treatment is oral gavage daily, for 60 days.
 The reproductive organs that were collected were weighed, and the epididymis and testis were used for further evaluations (count, viability, motility of spermatozoa), we also conducted histological tests for testis and epididymis.
 Results: The results showed that the treatment with Thiophante Methyl induced a decrease in concentration, motility, and viability of spermatozoa while the treatment of rats with fungicide associated with the grenade juice restored the concentration and the mobility of spermatozoa.
 Conclusion: Thiophanate Methyl (TM) caused structural changes in the epididymis and testes inducing a decrease in sperm quality, which would interfere with its function and contribute to infertility. On the other hand, GJ can prevent these changes by increasing the number of caudal sperm; thus, it could have an effect in improving male fertility.

Effect of genotypic richness, drought and mycorrhizal associations on productivity and functional traits of a dominant C4 grass

Abstract While the relationship between genetic diversity and plant productivity has been established for many species, it is unclear whether environmental conditions and biotic associations alter the nature of the relationship. To address this, we investigated the interactive effects of genotypic diversity, drought and mycorrhizal association on plant productivity and plant traits. Our mesocosm study was set up at the Konza Prairie Biological Research Station, located in the south of Manhattan, Kansas. Andropogon gerardii, the focal species for our study, was planted in two levels of genotypic richness treatment: monoculture or three-genotype polyculture. A rainout shelter was constructed over half of the experimental area to impose a drought and Thiophanate-methyl fungicide was used to suppress arbuscular mycorrhizal fungi in selected pots within each genotypic richness and drought treatment. Genotypic richness and mycorrhizal association did not affect above-ground biomass of A. gerardii. Drought differentially affected the above-ground biomass, the number of flowers and bolts of A. gerardii genotypes, and the biomass and the functional traits also differed for monoculture versus polyculture. Our results suggest that drought and genotypic richness can have variable outcomes for different genotypes of a plant species.

Bayesian Multi-Targets Strategy to Track Apis mellifera Movements at Colony Level.

Simple SummaryThe number of honey bee, Apis mellifera L., colonies has reduced around the globe, and one potential cause is their unintended exposure to sublethal stressors such as agricultural pesticides. The quantification of such effects at colony level is a very complex task due to the innumerable collective activities done by the individual within colonies. Here, we present a Bayesian and computational approach capable of tracking the movements of bees within colonies, which allows the comparison of the collective activities of colonies that received bees previously exposed to uncontaminated diets or to diets containing sublethal concentrations of an agricultural pesticide (a commercial formulation containing the synthetic fungicides thiophanate-methyl and chlorothalonil). Our Bayesian tracking technique proved successful and superior to comparable algorithms, allowing the estimation of dynamical parameters such as entropy and kinetic energy. Our efforts demonstrated that fungicide-contaminated colonies behaved differently from uncontaminated colonies, as the former exhibited anticipated collective activities in peripheral hive areas and had reduced swarm entropy and kinetic energies. Such findings may facilitate the electronic monitoring of potential unintended effects in social pollinators, at colony level, mediated by environmental stressors (e.g., pesticides, electromagnetic fields, noise, and light intensities) alone or in combination.Interactive movements of bees facilitate the division and organization of collective tasks, notably when they need to face internal or external environmental challenges. Here, we present a Bayesian and computational approach to track the movement of several honey bee, Apis mellifera, workers at colony level. We applied algorithms that combined tracking and Kernel Density Estimation (KDE), allowing measurements of entropy and Probability Distribution Function (PDF) of the motion of tracked organisms. We placed approximately 200 recently emerged and labeled bees inside an experimental colony, which consists of a mated queen, approximately 1000 bees, and a naturally occurring beehive background. Before release, labeled bees were fed for one hour with uncontaminated diets or diets containing a commercial mixture of synthetic fungicides (thiophanate-methyl and chlorothalonil). The colonies were filmed (12 min) at the 1st hour, 5th and 10th days after the bees’ release. Our results revealed that the algorithm tracked the labeled bees with great accuracy. Pesticide-contaminated colonies showed anticipated collective activities in peripheral hive areas, far from the brood area, and exhibited reduced swarm entropy and energy values when compared to uncontaminated colonies. Collectively, our approach opens novel possibilities to quantify and predict potential alterations mediated by pollutants (e.g., pesticides) at the bee colony-level.

2-Aminoselenazoles and 2-aminothiazoles: One-pot synthesis and control of the fungus Colletotrichum lindemuthianum in common beans.

Anthracnose, caused by the fungus Colletotrichum lindemuthianum, increases losses in the production of common beans. As 1,3-diazoles can act against fungi by inhibiting the enzyme squalene epoxidase (SE), 2-aminoselenazoles and 2-aminothiazoles were synthesized and subjected to tests with the fungus. In addition, the interactions of the most promising substances with the enzyme SE were investigated in silico. Seventeen compounds (eight new) were prepared by a one-pot methodology. In vitro antifungal activities of these compounds against C. lindemuthianum were determined by the minimum inhibitory concentration (MIC) method. Most treatments differed from the control (water), and six azoles with the lowest MIC values underwent an assay employing common bean plants inoculated with the fungus. Among the best results were those from 2-(3-fluorophenyl)amino-4-phenyl-1,3-thiazole (16; 2857 μg mL-1 ), which reduced the severity of anthracnose in common beans to values statistically comparable to the commercial fungicide thiophanate-methyl (700 μg mL-1 ). The in silico affinity of compound 16 for SE was statistically equal to those calculated for several inhibitors of this enzyme. The results suggested that 2-(3-fluorophenyl)amino-4-phenyl-1,3-thiazole (16) could be considered a potential fungicidal lead compound for further structural optimization, which according to the in silico study acts via SE inhibition. © 2022 Society of Chemical Industry.

Evaluation of Pruning Wound Protection Products for the Management of Almond Canker Diseases in California.

Almond trunk and branch canker diseases constitute a major cause of tree mortality in California. Numerous fungal pathogens have been associated with these canker diseases and pruning wounds act as major infection courts. Before this study, there were no products registered in California for the management of these diseases. In this study, fungicidal products including synthetic chemistries, biocontrols, paint, and a sealant were evaluated for preventing fungal pathogen infection via pruning wounds. In four field trials conducted over two dormant seasons, 16 pruning wound treatments were tested using handheld spray applications against five almond canker pathogens, namely Botryosphaeria dothidea, Neofusicoccum parvum, Cytospora sorbicola, Ceratocystis destructans, and Eutypa lata. The fungicide thiophanate-methyl (Topsin M; United Phosphorus, Bandra West, Mumbai, India) provided 82% overall disease prevention against four fungal pathogens. The biological control agent, Trichoderma atroviride SC1 (Vintec; Bi-PA, Londerzeel, Belgium), tested at three application rates, resulted in 90 to 93% protection of pruning wounds in field trials, and for individual pathogens ranged from 81 to 100% protection for the three rates. At the time of this publication, Vintec is being considered for registration as a biological control product for the prevention of almond canker diseases, while Topsin M is recommended to growers for the prevention of almond canker diseases. This research indicates that effective protection of pruning wounds from infection by almond canker pathogens can be achieved with a one-time spray application of thiophanate-methyl or the biocontrol T. atroviride SC1 (recommended 2 g/liter) after pruning.

Sensitivity of Cercospora sojina to demethylation inhibitor and methyl benzimidazole carbamate fungicides

Cercospora sojina, the causal agent of frogeye leaf spot (FLS) of soybean (Glycine max), can cause significant yield losses. Foliar fungicide application is a common strategy used to control FLS; however, C. sojina strains with resistance to quinone outside inhibitor (QoI) fungicides have become widespread throughout U.S. soybean production regions. Because of QoI-resistance, demethylation inhibitor (DMI) and methyl benzimidazole carbamate (MBC) fungicides have become more important in managing FLS. Baseline sensitivity assays are important to monitor any shifts in fungicide sensitivity. Sensitivity of the DMI fungicides flutriafol and tetraconazole and the MBC fungicide thiophanate methyl were established for 145 C. sojina isolates collected prior to 2001(baseline isolates) and C. sojina isolates collected from 2007 to 2012 representing 12 states. Bioassays were conducted to assess effective fungicide concentration at which 50% of mycelium growth was inhibited relative to a non-fungicide control (EC50) for each isolate-fungicide combination. Baseline EC50 value means for flutriafol, tetraconazole, and thiophanate methyl were 0.268, 0.153, and 0.521 μg/ml. When means of EC50 values for isolates collected from 2007 to 2012 were compared to baseline sensitivity EC50 means, no significant difference (P < 0.05) was observed for sensitivities to flutriafol and tetraconazole. When this same comparison was done for sensitivity to thiophanate methyl, isolates collected in 2008 and 2012 were significantly more sensitive than the baseline isolates. Overall, these findings indicate no shift towards reduced sensitivity to flutriafol, tetraconazole, and thiophanate methyl. Based on these results, continued monitoring of C. sojina population sensitivity to DMI and MBC fungicides should occur.

Surface sterilization method for reducing contamination of Clinacanthus nutans nodal explants intended for in-vitro culture

Surface sterilization is a vital step in preparation of healthy and viable explants in tissue culture. Most surface contaminants can be eliminated by surface sterilization with a suitable sterilizing agent. The study aimed to present an effective disinfection method for Clinacanthus nutans shoot regeneration using nodal segments. A total of four different sterilization approaches were conducted by treating nodal explants with various concentrations of sterilizing agent. Sterilizing agents used were Rhizophora apiculata Pyroligneous acid (PA), sodium hypochlorite (Clorox) thiophanate-methyl (fungicide), and Mercuric chloride (HgCl2). Nodal explant then was cultured on plant growth regulator-free Murashige and Skoog (MS) basal medium. This study sterilizing agents revealed that PA showed strong bactericidal activity. However, it led to a high number of fungal contaminations. The pyroligneous acid did not exhibit a strong potential as a disinfectant for C. nutans nodal explant. Overall, HgCl2 exhibits the best reduction in fungal contamination and gives a significant result with thiophanate-methyl fungicide. Surface sterilization with mercuric chloride (0.2%) for 1 hour was the optimum concentration and duration, which resulted in the highest percentage of nodal explant survival and viability. All viable nodal segments developed into shoots. It had been concluded that the best surface sterilization agent was HgCl2.

Long-Term Benefits of Protecting Table Grape Vineyards against Trunk Diseases in the California Desert

Grapevine trunk diseases (GTD) are caused by several fungal species and are major limiting factors to vineyard productivity and profitability in all viticulture areas. This study is aimed at addressing the gap in the knowledge with regards to measuring the long-term benefits of post-pruning fungicide application on trunk diseases incidence and crop yield in grape production systems. It also calculated the net economic benefit of implementing such practice over the vineyard lifespan. We selected a newly planted commercial table grape vineyard in the California desert and divided it in two blocks. In one block, the registered fungicide thiophanate-methyl was mechanically applied on pruning wounds for six consecutive years, while the other half remained untreated. Our results showed a significant lower GTD incidence and vine replants in treated blocks combined with a significant increase of total and marketable fruit. Potential annual economic benefits of applying fungicide on pruning wounds appear to be in the range of $8500–$12,500 per hectare annually in a 50–75% disease control scenario.

Baseline sensitivity and action mechanism of the sterol demethylation inhibitor flusilazole to Valsa mali

The apple Valsa canker caused by Valsa mali is a devastating branch disease that has seriously threatened the development of the apple industry worldwide. In current study, a total of 115 V. mali strains collected from different apple orchards in Shaanxi Province of China during 2016 and 2017 were tested for their sensitivity to flusilazole. The average EC50 (effective concentrations causing 50% mycelial growth inhibition) value of all tested strains for flusilazole was 0.0892 (±0.0036) μg/mL and the frequency distribution of the EC50 values was unimodal. Flusilazole exhibited both excellent protective and curative activity on detached apple branches, which was significantly better than the commonly used fungicide thiophanate-methyl. After flusilazole treatment, mycelia twisted with offshoot of top increased, the V. mali strains lost the ability of fruiting body production, and cell membrane permeability of the mycelia increased while ergosterol content and pectinase activity decreased. The expression of pectinase genes involved in virulence down-regulated after flusilazole treatment. This study is the first report on the baseline sensitivity of V. mali to flusilazole. These results indicated that flusilazole has a great potential to play an important role in the management of Valsa canker.

Treatments for Sclerotinia sclerotiorum on Inoculated Bean Seeds and Effects on Health and Physiological Quality

Considering the importance of bean cultivation, the objective was to prove the effectiveness of the seed microbiolization method in the control of Sclerotinia sclerotiorum (Ss) on black bean seeds (cv. IPR Tuiuiú), inoculated by the water restriction method. The treatments were fungicide methyl thiophanate + fluazinam (350.0 g L-1 + 52.5 g L-1); Trichoderma asperellum BV-10 (1.0 x 1010 viable conidia mL-1); T. harzianum strain CCT 7589 (1 x 109 CFUs L-1); Bacillus subtilis BV-02 (minimum 3.0 x 109 CFU mL-1); B. amyloliquefaciens isolated BV03 (minimum 3.0 x 109 CFU L-1); Positive control (seeds exposed to Ss); Negative control (NC) + fungicide; NC + T. asperellum; NC + T. harzianum; NC + B. subtilis; NC + B. subtilis; and NC (PDA medium plus restricting). To verify the effects on germination, vigor, and the health of bean seeds, and seedling emergence in the field. Microbiolization with T. asperellum and T. harzianum, provides improvement in germination, vigor, and health, but is not superior to fungicide treatment. Bacillus subtilis and B. amyloliquefaciens, in seeds not inoculated with the pathogen, produce the best results for green and dry mass (g). These may be used in the integrated management of white bean mold.

Enantioselective Synthesis and Antifungal Activity of C18 Polyacetylenes.

Fungal pathogens cause serious crop diseases and decrease crop yields and quality. Polyacetylene alcohols are plant secondary metabolites and bioactive against various pathogenic fungi. They are, however, difficult to synthesize. In the present study, an efficient and highly enantioselective method (>98% ee) was established and employed to achieve the synthesis of the natural C18 polyacetylenes (S,E)-octadeca-1,9-dien-4,6-diyn-3-ol 1, (3R,10R,E)-octadeca-1,8-dien-4,6-diyne-3,10-diol 2, and their analogs. The title compounds were structurally characterized and biologically evaluated for fungicidal activities. The compounds exhibited high potencies against eight pathogenic fungal species tested, such as Colletotrichum gloeosporioiles, Bipolaris sorokiniana, Fusarium graminearum, and Fusarium pseudograminearum, with half-maximum effective concentrations ranging from 8 to 425 μg/mL, being similar to those of the fungicide thiophanate-methyl (3-408 μg/mL). These compounds are potential natural fungicides and fungicide lead candidates for further structural and property improvements.

Biocontrol activity and putative mechanism of Bacillus amyloliquefaciens (SF14 and SP10), Alcaligenes faecalis ACBC1, and Pantoea agglomerans ACBP1 against brown rot disease of fruit

This study aimed at evaluating the antagonistic activity of 16 bacterial strains for the control of brown rot disease caused by Monilinia fructigena, and M. laxa under in vitro and a semi-commercial large-scale trial. These bacterial antagonists’ belonging to the genera Alcaligenes, Bacillus, Brevibacterium, Pantoea, Pseudomonas, and Serratia were previously proven effective for control of fire blight of apple. The in vitro dual culture bioassay showed the highest inhibition rates of mycelial growth ranging from 55 to 95% and from 43 to 94% for M. fructigena and M. laxa, respectively. The in vivo bioassay showed moderate and strong inhibition for M. fructigena and M. laxa, respectively. The inhibition rates were dependent on incubation time as well as pathogen virulence. The free-cell bacterial filtrate revealed substantial mycelial growth inhibition ranging from 66 to 86%. The inhibition of conidial germination was from 32 to 78%, suggesting the involvement of metabolites in their biocontrol activity. The antifungal effect of the volatile compounds (VCOs) was observed for all bacteria with mycelial inhibition varying from 12 to 70%. Overall, their efficacy was substantially affected by the nature of the bacterial strains and the modes of action. Taken together, these results underscore that ACBC1 and SF14 for M. fructigena and SP10 and ACBP1 for M. laxa were the most effective bacterial strains. These strains were confirmed effective in a semi-commercial large-scale trial. Interestingly, their efficacies were found to be comparable to those of both commercial BCAs (B. subtilis Y1336 and P. agglomerans P10c), but slightly lower than thiophanate-methyl fungicide. The ability of most bacterial strains to produce lytic enzymes (Amylase, Protease or Cellulase) and lipopeptides (bacillomycin, fengycin, iturin and surfactin) was demonstrated by biochemical and molecular analyzes. Therefore, our findings suggest that the bacterial antagonists ACBC1, SF14, SP10 and ACBP1, have the potential to prevent brown rot disease.

Antagonism of Trichoderma-based biofungicides against Brazilian and North American isolates of Sclerotinia sclerotiorum and growth promotion of soybean

The antagonistic activity of Trichoderma asperellum (aerial conidia) and T. harzianum (microsclerotia) Pers. (1801) (Hypocreales: Hypocreaceae) was evaluated against six isolates of Sclerotinia sclerotiorum (Lib.) de Bary (Helotiales: Sclerotiniaceae) from Brazil and the USA and further assessed for their enhancement of soybean growth. The fungicide thiophanate-methyl was included as a standard in all experiments. In vitro assay revealed that thiophanate-methyl and Trichoderma spp. effectively suppressed carpogenic and myceliogenic germination of sclerotia. The S. sclerotiorum isolates from Brazil appeared to be less susceptible than those from the USA to both chemical and biological treatments. The in vivo seed coating test using thiophanate-methyl or Trichoderma spp. substantially improved seed germination and suppressed growth of all S. sclerotiorum isolates to varying degrees. Moreover, soybean biomass of shoots and roots, and root nodulation were increased by either thiophanate-methyl or Trichoderma species. Collectively, these results underline the antagonistic activity of Trichoderma spp. against S. sclerotiorum isolates, the importance of Trichoderma spp. to improve soybean growth, and the bioactivity of Trichoderma microsclerotia through seed coating.