Inhibition Of Mycelial Growth Research Articles

Resistance to Azole Drugs by Fungal Species Isolated from Date Palm Samples within Lafia Metropolis, Nigeria

Fungal species infecting fruits are developing resistance to some antifungals. The study determined prevalent fungi in date palm fruits and their resistance to azole antifungals. Dried date palm fruit samples were collected from Modern Market, Old Market, Alhamis Market, Koro Market and Tomato Market in Lafia Metropolis, Nigeria and fungi isolated from them. Antifungal susceptibility test as a zone of inhibition of fungal mycelial growth were recorded for terbinafine, clotrimazole, nystatin, metronidazole and fluconazole. Dates from the old market had the highest contamination with 6.0×103 ± 4.2 cfu/g, while samples from Koro market with 2.5×103 ± 1.7 cfu/g were the least contaminated. A total of 84 fungi were isolated, Aspergillus niger was the most predominant species while Aspergillus versicolor was the least predominant. Terbinafine was the most effective azole against the fungal species isolated with a zone of inhibition of 43 mm in diameter, while fluconazole was the least effective with the zone of inhibition of 0 mm. The organism most susceptible to the antifungal drugs was Aspergillus niger, while Penicillium chrysogenum was the most resistant. Results of this study indicated that, date palm fruits around the Lafia markets were more susceptible to Aspergillus niger contamination than other fungal species, and Terbinafine was the best azole antifungal drug. The study recommends that further research should be carried out with respect to the resistance developed against azoles by the fungal species.

In-vitro Efficacy of Different Chemical Fungicides and Plant Extracts Against Alternaria alternata Causing Alternaria Leaf Spot Disease in Brinjal

Five different chemical fungicides and three plant extracts were evaluated against Alternaria alternate causing Alternaria leaf spot disease in brinjal. The experiment was carried out in the laboratory of plant pathology at Chaudhary Charan Singh University Meerut, during kharif season 2021-22. During survey the maximum disease incidence was recorded (37.8%) Rajpura in Meerut and minimum (10.9%) incidence was recorded in Lakhaoti, survey and metrological data presented in the (Tables 2 & 3). The incidence of the disease varied from 10.9 to 37.8 percent due to difference in environmental condition. The concentration of all fungicides and Plant-extracts was kept at 500, 1000 and 2000 ppm.  Mycelial growth was measured to continue zero to ten days. Mainly four chemical fungicides (Thaiophinate Methyl 70%WP, Propineb 70% WP, Carbendazim 50%WP and Chlorothalonil 75% WP) and Neem extract significantly inhibited the mycelial growth of the pathogen (Alternaria alternata). Among all those, four fungicides and Neem extract giving the better results. Maximum 100% mycelial growth inhibition was recorded in Thaiophinate Methyl 70%WP, 94.45% mycelial growth inhibition was recorded in Propineb 70% WP, 86.09% mycelial growth inhibition was recorded in Carbendazim 50%WP and 84.80 growth inhibition was recorded in Chlorothalonil 75% WP and in plant extract 18.53% inhibition was observed in Neem and 14.33% inhibition was observed in garlic. However, Azoxystrobin 23% SC and Onion also had some effect, which is mentioned in the result of the paper.

Synthetic Microbial Community Members Interact to Metabolize Caproic Acid to Inhibit Potato Dry Rot Disease.

The potato dry rot disease caused by Fusarium spp. seriously reduces potato yield and threatens human health. However, potential biocontrol agents cannot guarantee the stability and activity of biocontrol. Here, 18 synthetic microbial communities of different scales were constructed, and the synthetic microbial communities with the best biocontrol effect on potato dry rot disease were screened through in vitro and in vivo experiments. The results show that the synthetic community composed of Paenibacillus amylolyticus, Pseudomonas putida, Acinetobacter calcoaceticus, Serratia proteamaculans, Actinomycetia bacterium and Bacillus subtilis has the best biocontrol activity. Metabolomics results show that Serratia protoamaculans interacts with other member strains to produce caproic acid and reduce the disease index to 38.01%. Furthermore, the mycelial growth inhibition after treatment with caproic acid was 77.54%, and flow cytometry analysis showed that the living conidia rate after treatment with caproic acid was 11.2%. This study provides potential value for the application of synthetic microbial communities in potatoes, as well as the interaction mechanisms between member strains of synthetic microbial communities.

Bacillus amyloliquefaciens: a versatile antimicrobial Firmicute for the suppression of wilt caused by Ralstonia pseudosolanacearum in tomato

ABSTRACT Rhizosphere bacteria based biological control strategy is an eco-friendly approach to protect crops from various plant diseases. Among these, spore-forming Bacillus, abundant in the rhizosphere, provide unique advantages for plant health. This study focused on characterising two tomato rhizosphere-associated Bacillus amyloliquefaciens strains (Trb7 and Trb11), highly effective against the bacterial wilt pathogen Ralstonia pseudosolanacearum in vitro. Species identification was based on partial 16S rRNA gene sequencing, supported by phylogenetic analysis. Five antimicrobial peptide (AMP) genes (surfactin, fengycin, bacilysin, subtilin, and spore protein) were detected in both the isolates of B. amyloliquefqciens using specific molecular markers. Greenhouse trials showed that prophylactic application of these isolates led to an 83.4% reduction in tomato bacterial wilt, with only 16.6% wilt incidence compared to the 100% in the R. pseudosolanacearum-inoculated control. Moreover, these B. amyloliquefaciens isolates exhibited plant-growth-promoting traits in vitro. Interestingly, they also showed significant inhibition of mycelial growth against Sclerotium rolfsii and Alternaria alternata, major fungal pathogens in tomatoes. Overall, our findings highlight the potent bactericidal role of B. amyloliquefaciens isolates in suppressing R. pseudosolanacearum in tomatoes. Key highlights Two among the 100 Bacillus displayed antibacterial activity against Ralstonia pseudosolanacearum. Antibacterial firmicutes was identified as Bacillus amyloliquefaciens through the 16S rRNA gene sequence analysis. Five AMP genes (srfAA, fenD, bacA, spas, and spoVG) were identified in the isolates. Delivery of B. amyloliquefaciens drenching on rhizosphere significantly reduced wilt. Additionally, B. amyloliquefaciens showed the antifungal activity on Sclerotium rolfsii and Alternaria alternata.

Sensitivity to fungicides of Botrytis cinérea (Pers.) isolated from raspberry (Rubus idaeus L.)

Objective: To evaluate the sensitivity of B. cinerea isolated from raspberry to nine fungicides alone and in combination with potassium silicate. Design/methodology/approach: The study evaluates the sensitivity of four isolates obtained from four raspberry plantations in October 2022, which were identified in a previous study as B.cinerea based on morphological, morphometric and molecular characteristics, to nine fungicides alone and combined with potassium silicate. B. cinerea was planted in PDA culture medium modified with fungicides plus potassium silicate, and mycelial growth and mycelial growth inhibition percentage (PICM) were evaluated. A completely randomized design with six repetitions and two controls was used, an ANOVA and Tukey’s mean comparison test were performed. Results: B. cinerea isolated from CITAP showed lower growth with fluazinam (PICM = 100 ), while with azoxystrobin it presented a PICM equal to 0. B. cinerea isolated from Paso del Cristo and Sierra Negra 2 had lower growth with fluazinam (PICM = 100), while with boscalid and azoxystrobin it showed a PICM equal to 0. In Sierra Negra 1, iprodione controlled B. cinerea better with a PICM equal to 100, while azoxystrobin showed a PICM equal to 0. All the isolates were sensitive when fungicides were combined with potassium silicate. Findings/conclusions: All the isolates were sensitive to the fungicides fluazinam, fenhexamid, thiophanate methyl, captan, pyrimethanil, fludioxonil and iprodione. The isolates from Sierra Negra 1 and CITAP were sensitive to boscalid, while those from Sierra Negra 2 and Paso del Cristo were insensitive; 100 % of the isolates were insensitive to azoxystrobin, which suggests that they could be resistant; finally, potassium silicate potentiates the effect of fungicides.

Synthesis of the First Representatives of new 3,3a‐Dihydro‐1H‐Imidazo[4′,5′:4,5]Imidazo[2,1‐b]thia(selena)zole Heterocyclic Systems with Fungicidal Activity

AbstractThe first representatives of new fused tricyclic heterosystems, namely 3,3a‐dihydro‐1H‐imidazo[4′,5′:4,5]imidazo[2,1‐b]thiazoles and 3,3a‐dihydro‐1H‐imidazo[4′,5′:4,5]imidazo[2,1‐b][1,3]selenazoles have been synthesized through the regioselective reaction of diethyl acetylenedicarboxylate with semithioglycolurils, thioglycolurils or selenoglycolurils. Study of antifungal properties of the obtained compounds against Venturia inaequalis (V. i.), Rhizoctonia solani (R. s.), Fusarium oxysporum, Fusarium moniliforme, Bipolaris sorokiniana (B. s.) and Sclerotinia sclerotiorum phytopathogenic fungi has been performed. Tested compounds possessed good inhibition activity against R. s., B. s. with 45–94 % by mycelium growth inhibition test method, which were more active than the well–known azole fungicide triadimefon as positive control. The best active thiazole derivative was established to be effective against R. s. (94 %), B.s. (65 %) and V. i. (60 %). Two selenazole derivatives showed good activity with 69 % inhibition against R. s.

Influence of seagrass traits on the diversity of endophytic fungi

Abstract. Kinamot VB. 2024. Influence of seagrass traits on the diversity of endophytic fungi. Biodiversitas 25: 1254-1263. The interest in endophytic fungi has grown recently because of their potential to enhance plant growth, tolerate stresses, and modulate phytohormone synthesis. Understanding how plants influence their endophytic fungal assemblage is vital to manipulating them for biotechnological applications. In this study, Bray-Curtis analysis determined the variation of endophytic fungal assemblage among different seagrass species. Leaf/root area, leaf/root dry matter content, leaf mass per area, leaf toughness, and specific leaf area of seagrasses were measured using a standard protocol. The Folin-Ciocalteau method was utilized to quantify the phenolic and tannin contents in seagrasses using tannic acid as standard. Canonical correspondence analysis correlated the influence of seagrass traits on endophytic fungal diversity. Results showed that endophytic fungal diversity varied with seagrass hosts in which higher similarity of the fungal assemblage was observed among the same seagrass species than in different seagrass species. The seagrass traits mediated the variation of endophytic fungi. Phenolic and tannin in seagrasses significantly influenced the diversity of endophytic fungi. An antifungal assay using the methanolic crude extract of seagrasses had 80-100% mycelial growth inhibition to the five species of endophytic fungi tested, which could be accounted for the chemicals like phenol and tannin that the seagrass hosts produce. 

Efficacy of different fungicides against Ascochyta rabiei and Botrytis cinerea associated with chickpea

Ascochyta rabiei and Botrytis cinerea have been reported to cause blight and gray mold diseases in chickpea in different parts of the world and cause a significant economic loss to crop. In the present investigation, an in vitro evaluation of fungicides was conducted to find out the sensitivity and fungicide concentration in inhibiting the growth of Ascochyta rabiei and Botrytis cinerea. In vitro evaluation of fungicides revealed that, among five fungicides, bavistin (carbendazim 50 WP) a systemic fungicide was highly effective in inhibiting the mycelial growth with 100% inhibition at all the concentrations tested followed by baycor (bitertenol WP (25% w/w), with 98.88% inhibition at 500 ppm concentration and captan with 80% mycelia growth inhibition in A.rabiei. The fungicides such as chlorothalonil, copper oxychloride, and bitertanol at all concentrations were ineffective against B. cinerea. The fungicides that were effective under laboratory conditions could be further evaluated under field conditions to validate their efficacy and they could be incorporated as a component in integrated disease management in chickpea.

Antifungal efficacy of chitosan extracted from shrimp shell on strawberry (Fragaria × ananassa) postharvest spoilage fungi

The strong demand for biological materials in the food industry places chitosan at the forefront of other biopolymers. The present study aims to evaluate the antifungal properties of chitosan extracted from shrimp shell waste (Parapenaeus longirostris) against post-harvest strawberry (Fragaria × ananassa) spoilage fungi. The physicochemical characteristics (DD, Mw, and solubility) of extracted chitosan were determined. In addition, functional characteristics were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The antifungal effect of chitosan on mycelial growth and spore germination of Aspergillus niger, Botrytis cinerea, Fusarium oxysporum, and Rhizopus stolonifer was evaluated. Yield, degree of deacetylation, molecular weight, and solubility were 21.86%, 83.50%, 180 kDa, and 80.10%, respectively. A degree of deacetylation of 81.27% was calculated from the FTIR spectrum and a crystallinity index of 79.83% was determined from the X-ray diffraction pattern. SEM images of extracted chitosan showed a combination of fibrous and porous structure. At 3% chitosan, mycelial growth inhibition rates of A. niger, B. cinerea, F. oxysporum, and R. stolonifer ranged from 81.37% to 92.70%. At the same chitosan concentration, the percentages of spore germination inhibition of the isolated fungi ranged from 65.47% to 71.48%. The antifungal activity was highly dose-dependent. As a natural polymer, chitosan offers a convincing alternative to synthetic antimicrobials for the post-harvest preservation of strawberries. Its potential lies in its ability to inhibit the growth of spoilage fungi.

Antagonistic potential of soil fungi as biocontrol agent against rice pathogens

Antagonistic potential of six soil fungi viz., Aspergillus flavus Link., A. fumigatus Fresen., A. niger Tiegh., Penicillium sp., Trichoderma harzianum Refat. and T. viride Pers. against eight pathogenic fungi viz., Alternaria alternata (Fr.) Keissler, Curvularia lunata (Wakker) Boedijn, Drechslera oryzae Breda de Haan (Subramanian and Jain), Fusarium moniliforme Sheldon, F. solani (Mart.) Sacc. Microdochium oryzae (Hashloka and Yokogi) Sam. and Hal., Pestalotiopsis guepinii (Desm.) Stay. and Sarocladium oryzae (Sawada) W. Gams and D. Hawks of rice were evaluated. In colony interaction, the highest growth inhibition (88%) was observed owing to T. harzianum against Alternaria alternata.Volatile substances from soil fungi inhibited the  radial growth of the test pathogens which varied from 8.33 to 57.36%.The highest inhibition (57.36%) was found owing to T. harzianum against P. guepinii. The inhibition of mycelial growth of the test pathogens ranged from 29.05 to 64.5% owing to non volatile substances of the soil fungi. The highest mycelial growth inhibition was observed owing to T. harzianum against C. lunata. Trichoderma harzianum may be exploited commercially to control rice pathogens. Bangladesh J. Bot. 53(1): 101-108, 2024 (March)

Efficient antidermatophytic agents to fight clinical Tinea spp. using Salvia multicaulis and Hypericum scabrum-based sustainable NCs

Increased problems associated with side effects and microbial resistance of chemical drugs have promoted the research focus of herbs and herbs-based medicines as renewed interest. The present study studied the antifungal potential of Hypericum scabrum (H. scabrum), Salvia multicaulis (S. multicaulis) plants and their derived sustainable NCs against dermayophyton species. These plants were used as free-toxic solvent media and phytogradiant reductants to fabricate nanoformulations as alternative antimycotic drugs. Analysis of antifungal activity showed a noticeable inhibition of the trychophyton mycelial growth when cultured on SDA mixed with different doses of the plant extract, particularly 50% H. scabrum that stopped mycelial growth of  T. mentagrophytes  and T. verrcuosum thoroughly after 10-day incubation by of 100 % MGI, followed by Ag@Fe3O4@SiO2 with particle size around 20 to 60 nm,  that record ( 67.64 and 63,.33 % of MGI) by 50 µg ml−1 application respectively. The lowest effect of  H. scabrum and Ag@Fe3O4@SiO2 at high concentrations was against T. simii (44.44 % and 16 % MGI). The maximum antifungal activity of 50 % Salvia multicaulis and 50 µg ml−1 CuO@SiO2 NC with an average diameter of 60 nm was found against T. mentagrophytes and T. verrcuosum with (66.66 and 51.47 % MGI), respectively, while the minimum activity was found against T. quinckeanum and T. simii (33.33 and 13.33 % MGI), respectively. Thus, these plant extracts and NCs could be used to develop a new medication for dermatophytosis. 

Use of natural-based commercial products as an alternative for providing bioprotection against verticillium wilt of olive.

As a result of the ineffectiveness of existing control methods against Verticillium dahliae, the causal agent of verticillium wilt of olive (Olea europaea; VWO), it is necessary to search for sustainable and environmentally friendly alternatives, such as bioprotection by products based on plant extracts and other naturally synthesized compounds. Therefore, present study aimed to evaluate the effects of seven natural-based commercial products on the inhibition of mycelial growth, the germination of V. dahliae conidia and microsclerotia, and disease progression in olive plants (cv. Picual). Aluminium lignosulfonate and a copper phosphonate salt (copper phosphite) were included for comparative purposes. The seaweed and willow extracts and copper phosphite inhibited V. dahliae mycelial growth by more than 50% at the high doses tested. Most of the products inhibited conidial germination by up to 90% compared to the control at the high doses tested. However, none of the products showed efficacy above 50% in inhibiting microsclerotia germination. The willow extract was the most effective at reducing disease severity and progression in olive plants, with no significant differences compared to the non-inoculated negative control. The results of the present study suggest that the use of natural-based products (i.e. seaweed and willow extracts) is a potential sustainable alternative in an integrated VWO control strategy. © 2024 Society of Chemical Industry.

Sensitivity of 40 Pythium species to the new fungicide Picarbutrazox

AbstractPicarbutrazox is the active ingredient of Vayantis®, a novel seed treatment fungicide developed by Syngenta and discovered by Nippon Soda. Vayantis® received registration from the US EPA in 2021. Picarbutrazox is a systemic fungicide and belongs to the tetrazolyloximes chemical group of fungicides, and its mode of action is still unknown (FRAC group U17). Picarbutrazox targets oomycete plant pathogens and controls diseases caused by Pythium, Phytophthora, and downy mildews. Picarbutrazox is in a new mode-of-action group with no known cross-resistance to other oomycete compounds. The sensitivity to Picarbutrazox of 528 isolates belonging to 40 different Pythium species was determined in vitro. Pythium isolates were collected from infected plants including corn, soybean, cotton, and other crops from 17 different states. Pythium isolates were also obtained from collections kept at universities. Isolates were identified at the species level using morphological and molecular tools. Mycelial growth inhibition was quantified using the following Picarbutrazox concentrations: 0, 0.00001, 0.0001, 0.001, 0.01, and 0.1 mg/L. All the species of Pythium tested were sensitive to Picarbutrazox. The sensitivity distribution (EC50 values) across all the Pythium species tested had a mean sensitivity of 0.000376 mg ai/L. The Picarbutrazox sensitivity of 40 species of Pythium species has been documented, and results demonstrate the high in vitro intrinsic activity of this fungicide to control Pythium species. The high potency of Picarbutrazox to control Pythium diseases in corn, soybeans, cotton, and other crops has also been demonstrated under field conditions when used as a seed treatment. Picarbutrazox, with its novel mode of action, will contribute to the management of potential fungicide resistance issues developed by other fungicide products controlling Pythium, including mefenoxam and ethaboxam.

Molecular identification and management of mycotoxigenic fungi in stored corn Grains

AbstractMycotoxin-producing molds which considered as common maize grains contaminants are the genera Fusarium, Aspergillus and Penicillium. There are natural and safe ways to protect grains from mold contamination as the use of essential oils and chemical treatments. A total number of 25 samples were used to study the natural frequency in five governorates in Egypt, Molecular identification indicated that the most frequent fungi were Fusarium verticillioides, Aspergillus niger, Talaromyces verruculosus, Aspergillus flavus and Aspergillus terreus. The in vitro studies have been done to determine mycelial growth and spore germination inhibition of the two A. flavus; isolated and reference isolates. Thyme and acetic acid were tested in direct contact assay to study their effects on mycelial growth. Treatments showed significant impact on mycelial growth and spore germination inhibition of both A. flavus isolates. In the postharvest application treatments: as vapour and carrier contact assay, Thyme and Acetic acid were tested to determine their influence on growth and aflatoxin production in A. flavus isolates by liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS). Results indicated that both treatments were effective in inhibition of aflatoxin production in both vapour and carrier assays as they succeeded in reducing AFB1 while they inhibited completely the production of AFB2. The extent of the inhibition of aflatoxin production was dependent on the concentration and storage duration of treatments applied.

Biofilm containing the Thymus serpyllum essential oil for rice and cherry tomato conservation.

Fungal pathogens cause major yield losses in agriculture and reduce food quality and production worldwide. To evaluate new safer alternatives to chemicals for disease management and preserve the shelf life of food, this research was conducted to: determine the chemical composition of the essential oils (EOs) of Thymus serpyllum and Thymus piperella chemotypes 1 and 2; investigate the antifungal potential of EOs in vitro against: Alternaria alternata, Bipolaris spicifera, Curvularia hawaiiensis, Fusarium oxysporum f. sp. lycopersici, Penicillium italicum, Botryotinia fuckeliana; evaluate a natural T. serpyllum extract biofilm to conserve rice grain and cherry tomatoes. EOs were analyzed by GC-MS+GC-FID. EOs' antifungal activity was evaluated by dissolving Thymus extracts in PDA. Petri dishes were inoculated with disks of each fungus and incubated at 25°C for 7 days. The T. serpyllum EO displayed the best Mycelial Growth Inhibition. The antifungal effect of the T. serpyllum EO biofilm was evaluated on rice caryopsis. Disinfected grains were dipped in a conidial suspension of each fungus and sprayed with EO (300 and 600 μg/mL) prepared in Tween 20. Grains were stored. The percentage of infected grains was recorded for 30 days. The T. serpyllum EO effect on cherry tomato conservation was evaluated in vivo. Wounded fruit were immersed in the T. serpyllum EO (300 and 400 μg/mL) and inoculated with Fusarium oxysporum f. sp. lycopersici. Fruit were evaluated for 7 and 14 days. Chemical profiles thymol/carvacrol for T. serpyllum, carvacrol for T. piperella Tp1 and thymol for T. piperella Tp2 were defined. The three evaluated EOs reduced all the studied phytopathogens' fungal growth. The T. serpyllum biofilm was effective with rice storage and against Fusarium oxysporum f. sp. lycopersici for extending the shelf life of tomatoes in warehouses and storing postharvest cherry tomatoes. We suggest applying these EOs as biofilms for safe food conservation to replace synthetic products.

Effect of Bacillus subtilis, Soil Amendments and Microalgae Treatment on Fusarium equiseti of Turmeric (Curcuma longa L.) Prayagraj, India

Rhizome rot of turmeric caused by Fusarium equiseti emerge as a significant soil-borne threat to crop health. An experiment was conducted to evaluate the effect of Bacillus subtilis, soil amendments and microalgae treatment on Fusarium equiseti of Turmeric (Curcuma longa L). Experiment was conducted under field condition at the courtyard of department of Plant Pathology, SHUATS, Prayagraj, during kharif season of 2022. Various soil treatments including farm yard manure (FYM), spent mushroom compost (SMC), and microalgae were used, along with rhizome treatment utilizing Bacillus subtilis. The experiment was carried out in Randomized Block design (RBD) with three (3) replications. Results revealed that in the soil application, (T5) i.e., the combination of all the treatments recorded minimum disease intensity (59.26%) which was significant over other treatments and control (T0) (33.86%). To evaluate the radial growth (mm) of Fusarium equiseti in turmeric, seven botanicals from Manipur viz., Zanthoxylum acanthopodium, Phlogacanthus thyrsiformis, Solanum xanthocarpum, Centella asiatica, Drymaria cordata, Persicaria chinensis and Gynura cusimbua were investigated in vitro at 10% and 30% concentration. The antagonistic effects of various botanicals were evaluated in vitro, demonstrating inhibition of mycelial growth. Among the tested botanicals, Zanthoxylum acanthopodium inhibited the highest inhibition rate (86.27%), followed by Phlogacanthus thyrsiformis (77.45%), Solanum xanthocarpum (75.48%), Persicaria chinensis (68.62%), Drymaria cordata (65.68%), Gynura cusimbua (62.74%) with Centella asiatica displaying the lowest inhibition rate (57.84%), all at a concentration of 30%. Overall, our findings highlight the potential of integrated management strategies involving biological control agents and soil amendments for sustainable management of Fusarium equiseti in turmeric cultivation. Implementation of these strategies holds promise for improving crop health, productivity, and sustainability in turmeric production systems.

Evaluation of phyllosphere bacterial biocontrol agents for the suppression of rice foliar diseases

AbstractPhyllosphere colonizing antagonistic bacterial isolates were evaluated for managing major rice foliar diseases, namely brown spot caused by Bipolaris oryzae and sheath rot caused by Sarocladium oryzae. Among these various isolates, Pseudomonas aeruginosa isolate 1 effectively inhibited the mycelial growth of B. oryzae and S. oryzae. The volatile compounds of Bacillus subtilis isolates effectively inhibited the mycelial growth of S. oryzae and B. oryzae. Non‐volatile compounds of P. aeruginosa isolate 2 and B. subtilis isolate 1 recorded the maximum inhibition of mycelial growth of B. oryzae and S. oryzae, respectively. P. aeruginosa isolates produced fluorescent pigments and hydrogen cyanide (HCN), whereas isolates of Bacillus spp. did not. All the isolates of P. aeruginosa and Bacillus spp. produced protease enzymes. P. aeruginosa isolates solubilized phosphate, whereas isolates of Bacillus spp. did not. Rice seeds treated with these bacterial suspensions showed improvement in plant growth parameters. The foliar application of two bacterial strains, namely P. aeruginosa isolate 1 + B. subtilis isolate 1 recorded the minimum brown spot and sheath rot disease incidence. Thus, the present showed that phyllosphere colonizing P. aeruginosa and B. subtilis have the potential application for managing foliar fungal diseases of rice plants.

Optimization of green silver nanoparticles as nanofungicides for management of rice bakanae disease

Rice bakanae, a devastating seed-borne disease caused by Fusarium species requires a more attractive and eco-friendly management strategy. The optimization of plant-mediated silver nanoparticles (AgNPs) as nanofungicides by targeting Fusarium species may be a rational approach. In this study, Azadirachta indica leaf aqueous extract-based AgNPs (AiLAE-AgNPs) were synthesized through the optimization of three reaction parameters: A. indica leaf amount, plant extract-to-AgNO3 ratio (reactant ratio), and incubation time. The optimized green AgNPs were characterized using ultraviolet–visible light (UV–Vis) spectroscopy, field emission scanning electron microscopy (FESEM) with energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), and powder X-ray diffraction (XRD) techniques. The optimal conditions for producing spherical, unique, and diminutive-sized AgNPs ranging from 4 to 27 nm, with an average size of 15 nm, were 2 g AiLAE at a 1:19 ratio (extract-to-AgNO3) and incubated for 4 h. Fusarium isolates collected from infected soils and identified as F. fujikuroi (40) and F. proliferatum (58 and 65) by PCR were used for seed infestation. The AgNPs exhibited concentration-dependent mycelial growth inhibition with EC50 values ranging from 2.95 to 5.50 μg/mL. The AgNPs displayed exposure time-dependent seed disinfectant potential (complete CFU reduction in F. fujikuroi (40) and F. proliferatum (58) was observed at a concentration of 17.24 μg/mL). The optimized green AgNPs were non-toxic to germinating seeds, and completely cured bakanae under net-house conditions, suggesting their great nano-fungicidal potency for food security and sustainable agriculture.

KARAKTERISASI MORFOLOGI DAN UJI ANTIFUNGI ISOLAT JAMUR Trichoderma spp. DARI TANAH GAMBUT TERHADAP PATOGEN PADA JARAK KEPYAR (Ricinus communis L.)

Castor oil (Ricinus communis L.) is an oil producing commodities that plays a role in meeting industrial and economic needs. Infection with the pathogen fungi caused a decrease in the production of castor oil. Biological control using Trichoderma spp. has been widely used. Trichoderma spp. known as one of the benefical biofungicide because it has high antagonistic properties inhibiting the growth pathogenic fungi. The purpose of this study was to obtain isolates and characters as well antifungal test for Trichoderma spp. isolated from peat soil to control pathogen Aspergillus sp. on castor been (Ricinus communis L.). Trichoderma spp. isolated from peat soil in Meranti Islands, Riau. The antagonistic activity the isolates against pathogen Aspergillus sp. was studied in vitro using dual culture and in vivo assay. In this study, six isolates of Trichoderma spp have isolated. Trichoderma sp. GBA5 has the highest growth rate on PDA and TSM medium. Trichoderma sp. GBA3 and Trichoderma sp. GBA4 were most effective in percentage inhibition of mycelial growth of test pathogen i.e 84,55%  and 83,71% respectively. In in vivo assay, only Trichoderma sp. GBA5 inhibited pathogen with the percent infected castor capsule was 51.66%.

Use of ginger extract and bacterial inoculants for the suppression of Alternaria solani causing early blight disease in Tomato

Early blight (EB), caused by Alternaria solani, is a serious problem in tomato production. Plant growth-promoting rhizobacteria promote plant growth and inhibit plant disease. The present study explored the bio-efficacy of synergistic effect of rhizobacterial isolates and ginger powder extract (GPE) against tomato EB disease, singly and in combination. Six fungal isolates from symptomatic tomato plants were identified as A. solani on the basis of morphological features i.e., horizontal septation (6.96 to 7.93 µm), vertical septation (1.50 to 2.22 µm), conidia length (174.2 to 187.6 µm), conidial width (14.09 to 16.52 µm), beak length (93.06 to 102.26 µm), and sporulation. Five of the twenty-three bacterial isolates recovered from tomato rhizosphere soil were nonpathogenic to tomato seedlings and were compatible with each other and with GPE. Out of five isolates tested individually, three isolates (St-149D, Hyd-13Z, and Gb-T23) showed maximum inhibition (56.3%, 48.3%, and 42.0% respectively) against mycelial growth of A. solani. Among combinations, St-149D + GPE had the highest mycelial growth inhibition (76.9%) over the untreated control. Bacterial strains molecularly characterized as Pseudomonas putida, Bacillus subtilis, and Bacillus cereus and were further tested in pot trials through seed bacterization for disease control. Seeds treated with bacterial consortia + GPE had the highest disease suppression percentage (78.1%), followed by St-149D + GPE (72.2%) and Hyd-13Z + GPE (67.5%). Maximum seed germination was obtained in the bacterial consortia + GPE (95.0 ± 2.04) followed by St-149D + GPE (92.5 ± 1.44) and Hyd-13Z + GPE (90.0 ± 2.04) over control (73.8 ± 2.39) and chemical control as standard treatment (90.0 ± 2). Ginger powder extracts also induce the activation of defence-related enzymes (TPC, PO, PPO, PAL, and CAT) activity in tomato plants. These were highly significant in the testing bacterial inoculants against A. solani infection in tomato crops.