Radial Mycelial Growth Research Articles

Investigating the Antagonistic Effects of Novel Combination Fungicides against Fusarium oxysporum f. sp. ricini under In-vitro Conditions

Aim: The study aimed to assess the efficacy of nine novel fungicide combinations against Fusarium oxysporum f. sp. ricini, the causal agent of wilt disease in castor. Methodology: The efficacy of fungicides was evaluated using the poisoned food technique under in-vitro conditions. Radial mycelial growth of the pathogen was measured across various concentrations (100 to 1000 ppm) of the fungicide combinations to determine their impact on mycelial inhibition. Results: Results indicated a substantial reduction in radial mycelial growth with increased fungicide concentration. Among the tested fungicides, Tebuconazole + Trifloxystrobin and Prochloraz + Tebuconazole recorded complete mycelial inhibition (100 %) at all the tested concentrations, demonstrating significant fungicidal activity followed by Hexaconazole + Captan with a mean mycelial inhibition of 85.2 %, indicating strong potential for disease management. In contrast, the least mean mycelial inhibition (24.7 %) was observed with Thiophanate methyl + Pyraclostrobin. Conclusion: These findings underscored the importance of selecting effective fungicide combinations to manage F. oxysporum f. sp. ricini, thereby enhancing crop protection and agricultural sustainability.

In vitro Efficacy of Different Fungicides against Leaf Blight of Sunflower

Sunflower is one of the major oilseed crops cultivated in India. Alternaria leaf blight is one of the fungal diseases of Sunflower caused due the pathogen Alternaria helianthi, which is one of the significant limitations in the cost-effective cultivation of Sunflower in India. It is estimated that 20 to 80% losses in yield and heavy defoliation have been observed due to A. helianthi causal agent of leaf blight of Sunflower. Present investigation on evaluation on efficacy of different fungicides against leaf blight of Sunflower under in vitro condition by using Completely Randomized Design was conducted at Department of Plant Pathology, Dr. Sharadchandra Pawar College of Agriculture, Baramati during. Under this study seven fungicides viz., Chlorothalonil 75% WP, Hexaconazole 5% EC, Carbendazim+Mancozeb 75% WP, Carbendazim 50% WP, Tebuconazole 25.9% EC, Propiconazole 25% EC and Azoxystrobin 23% SC were evaluated against the pathogen Alternaria helianthi causing leaf blight in Sunflower at their recommended concentration and observation on mean radial mycelial growth and percent mycelial growth inhibition of pathogen was calculated. Results revealed that among various fungicides the three fungicides viz., Hexaconazole 5% EC, Tebuconazole 25.9% EC and Propiconazole 25% EC were found most effective with minimum mean mycelial growth and having maximum and similar (94.44%) percent growth inhibition of pathogen and rest of the fungicides tested were comparatively less effective against the pathogen A. helainthi associated with leaf blight of Sunflower.

Effect of adjuvants on growth and spore attributes of <i>Metarhizium anisopliae</i> (Metsch.) Sorokin

The pathogenicity of the fungus, Metarhizium anisopliae, commonly referred to as the green muscardine fungus, has been demonstrated against numerous insect species inhabiting various habitats. Laboratory experiments were carried out to investigate the impact of naturally derived adjuvants on the growth and spore characteristics of M. anisopliae. The natural polysaccharide (guar gum, gum acacia and carboxymethyl cellulose), vegetable oil (groundnut and cottonseed oil) and a synthetic adjuvant were used in the study at three distinct concentrations: 0.05%, 0.1%, and 0.2% v/v or w/v. Among the various adjuvants tested, both gum acacia and guar gum at concentrations of 0.1% and 0.2% were observed to have a positive impact on the growth of the fungus, resulting in enhanced radial mycelial growth, conidiospore production, surface area coverage, and conidiospore germination. Conversely, this fundamental study highlights the detrimental effects of synthetic adjuvants on the growth and spore characteristics of M. anisopliae.

In vitro and in vivo Evaluations of the Antifungal Activity of Salicylic Acid and Silicon Against Ganoderma Boninense

Basal stem rot disease (BSR) in oil palms is one of the primary diseases that has led to the wide use of fungicides. This increased the development of fungal isolates resistant to fungicides and led to the search for alternative strategies to replace the use of fungicides. This study aimed to evaluate in vitro antifungal activity of salicylic acid (SA) and silicon (Si) in inhibiting mycelial growth of Ganoderma boninense using Poison Food Technique and to evaluate the in vivo efficacy of Si treatment on oil palm seedlings growth and resistance towards G. boninense. Percentage inhibition of radial mycelial growth (PIRG) was assessed, and Si treatment significantly reduced mycelial radial growth of G. boninenseup to 100% inhibition at concentrations of 200 and 250 mg/L. The half-maximal effective concentration (EC50) for Si was 68.57 mg/L, while for SiO2, it was 273.95 mg/L. The EC50 for salicylic acid was 381.33 mg/L. For in vivo evaluation, oil palm seedlings treated with Si at 150, 200, and 250 mg/L showed the lowest severity of leaf chlorosis and necrotic symptoms, which were 7.36%, 6.49%, and 4.05%, respectively. In contrast, the seedlings without Si showed the highest severity of leaf symptoms. Examination of internal bole tissues of oil palm seedlings treated with Si at a concentration of 250 mg/L also recorded a 3.0% mean percentage of disease severity compared to the untreated infected seedlings, which showed 35.0% disease severity. Our findings demonstrated the potential of Si application in controlling the BSR disease caused by Ganoderma boninense.

Isolation, antioxidant and antifungal activity of furanocoumarins from the leaves of Heracleum vicinum Boiss.

In this work, coumarin compounds were extracted by ultrasonic-microwave synergistic extraction from the leaves of Heracleum vicinum Boiss.. The five furanocoumarins—pimpinellin, isopimpinellin, bergapten, xanthotoxin, and imperatorin—that were isolated from the leaves of Heracleum vicinum Boiss. were quantified using HPLC and GC, and their quantities in the aboveground sections was determined. The antioxidant activities of five furanocoumarins were assessed with ABTS radicals and DPPH radicals, with the best scavenging effects of xanthotoxin and bergapten, with half maximal inhibitory concentration (IC50) of xanthotoxin for ABTS radicals and DPPH radicals of 1.85 mg/mL and 3.95 mg/mL, respectively, and bergapten for ABTS radicals and DPPH radicals IC50 of 1.68 mg/mL and 4.61 mg/mL, respectively. The antifungal activities of five furanocoumarins against trichophyton rubrum were evaluated. The minimum inhibitory concentration (MIC) of xanthotoxin (200 μg/mL) and imperatorin (12.5 μg/mL) showed the highest inhibitory effects against trichophyton rubrum. The inhibitory mechanism of xanthotoxin was discussed. When trichophyton rubrum was treated with 200 μg/mL of xanthotoxin, the spore germination rate was 34.92%, the nucleic acid leakage was 52.22%, the inhibition of radial growth of mycelium could reach 87.87%, and the content of ergosterol was reduced by 37.37%. It indicates that xanthotoxin was found to be able to damage mycelium shape, prevent spore germination and mycelium growth, kill mycelium cells and release intracellular materials, and obstruct the production of ergosterol. These results indicate that furanocoumarin is a potent active component that has an important role in Heracleum vicinum Boiss. leaves.

TiO2 nanoparticles: Green synthesis and their role in lessening the damage of Colletotrichum graminicola in sorghum.

Fungal pathogens pose a persistent threat to crop plants, risking global food security. Anthracnose of sorghum caused by Colletotrichum graminicola causes a considerable loss in sorghum production. This study aimed to manage the anthracnose disease in sorghum using green-synthesized TiO2 nanoparticles using pomegranate peel and to assess their impacts on the agroeconomic attributes of sorghum. Synthesized TiO2 nanoparticles showed strong dose-dependent antifungal activity against C. graminicola and significantly reduced mycelial radial growth, comparable to commercial fungicides. Foliar application of TiO2 at concentrations of 150 and 200 ppm reduced the disease index >60% in pot trials. Additionally, the effect of TiO2 NPs on the growth and yield of sorghum plants and the possible mechanism(s) behind the suppression of anthracnose disease were deciphered. TiO2 NPs also improved shoot and root length, biomass accumulation, penile size, number of grains, and grain weight in sorghum plants infected with C. graminicola. Application of TiO2 NPs significantly increased the content of defense-related biochemicals, including total phenolic contents, activities of defense-related enzymes (PO, PPO, and PAL), photosynthetic pigments (total chlorophyll contents and carotenoids), and total protein contents. Collectively, our study verified the potential of green-synthesized titanium dioxide nanoparticles to suppress anthracnose disease by activating a defense system and stimulating growth and yield promotion under pathogen stress.

Biocontrol Mechanisms of Three Plant Essential Oils Against Phytophthora infestans Causing Potato Late Blight.

Late blight, caused by the notorious pathogen Phytophthora infestans, poses a significant threat to potato (Solanum tuberosum) crops worldwide, impacting their quality as well as yield. Here, we aimed to investigate the potential use of cinnamaldehyde, carvacrol, and eugenol as control agents against P. infestans and to elucidate their underlying mechanisms of action. To determine the pathogen-inhibiting concentrations of these three plant essential oils (PEOs), a comprehensive evaluation of their effects using gradient dilution, mycelial growth rate, and spore germination methods was carried out. Cinnamaldehyde, carvacrol, and eugenol were capable of significantly inhibiting P. infestans by hindering its mycelial radial growth, zoospore release, and sporangium germination; the median effective inhibitory concentration of the three PEOs was 23.87, 8.66, and 89.65 μl/liter, respectively. Scanning electron microscopy revealed that PEOs caused the irreversible deformation of P. infestans, resulting in hyphal shrinkage, distortion, and breakage. Moreover, propidium iodide staining and extracellular conductivity measurements demonstrated that all three PEOs significantly impaired the integrity and permeability of the pathogen's cell membrane in a time- and dose-dependent manner. In vivo experiments confirmed the dose-dependent efficacy of PEOs in reducing the lesion diameter of potato late blight. Altogether, these findings provide valuable insight into the antifungal mechanisms of PEOs vis-à-vis late blight-causing P. infestans. By utilizing the inherent capabilities of these natural compounds, we could effectively limit the harmful impacts of late blight on potato crops, thereby enhancing agricultural practices and ensuring the resilience of global potato food production.

Bio-perfume guns: Antifungal volatile activity of Bacillus sp. LNXM12 against postharvest pathogen Botrytis cinerea in tomato and strawberry

Gray mold disease, caused by Botrytis cinerea is a major postharvest disease impacting fruits such as strawberries and tomatoes. This study explores the use of volatile organic compounds (VOCs) produced by Bacillus spp. as eco-friendly biocontrol agents against B. cinerea. In vitro experiments demonstrated that VOCs from Bacillus sp. LNXM12, B. thuringiensis GBAC46, and B. zhanghouensis LLTC93-VOCs inhibited fungal growth by 61.2%, 40.5%, and 21.6%, respectively, compared to the control. LNXM12 was selected for further experiments due to its highest control efficacy of 58.3% and 76.6% on tomato and strawberry fruits, respectively. The LNXM12 VOCs were identified through gas chromatography–mass spectrometry (GC–MS) analysis, and 22 VOCs were identified. Synthetic VOCs with the highest probability percentage, namely ethyloctynol, 3-methyl-2-pentanone (3M2P), 1,3-butadiene-N, N-dimethylformamide (DMF), and squalene were used in experiments. The results showed that the synthetic VOCs ethyloctynol and 3M2P were highly effective, with an inhibition rate of 56.8 and 57.1% against fungal mycelium radial growth at 120 μg/mL on agar plates. Trypan blue staining revealed strongly disrupted, deeper blue, and lysed mycelium in VOC-treated B. cinerea. The scanning and transmission electron microscope (SEM and TEM) results showed that fungal mycelium was smaller, irregular, and shrunken after synthetic VOC treatments. Furthermore, the synthetic VOCs Ethyloctynol and 3M2P revealed high control efficacy on tomatoes and strawberries infected by B. cinerea. The control efficacy on leaves was 67.2%, 66.1% and 64.5%, 78.4% respectively. Similarly, the control efficiency on fruits was 45.5%, 67.3% and 46.3% 65.1%. The expression of virulence genes in B. cinerea was analyzed, and the results revealed that selected genes BcSpl1, BcXyn11A, BcPG2, BcNoxB, BcNoxR, and BcPG1 were downregulated after VOCs treatment. The overall result revealed novel mechanisms by which Bacillus sp. volatiles control postharvest gray mold disease.

Evaluation of new generation fungicides against Ganoderma induced basal stem rot of oil palm

Basal stem rot (BSR), incited by Ganoderma spp. poses a significant challenge to the oil palm industry in India. A total of ten roots and basidocarps samples were taken from BSR-infected fields of Pedavegi, Andhra Pradesh, and identified as Ganoderma based on distinctive colony characters. To enhance identification accuracy, PCR with GB4 genus-specific primers, resulting in a 500 bp amplicon that confirmed the isolate affiliation with the Ganoderma genera. The efficacy of 13 fungicides against Ganoderma was evaluated through solid plate assay. Noteworthy inhibition of mycelial radial growth was observed with the eight fungicides at all tested doses, including Hexaconazole 5 per cent SC, Propiconazole 25 per cent EC, Tebuconazole 25.9 per cent EC, Tebuconazole 50% + Trifloxystrobin 25% w/w WG, Propiconazole 13.9% + Difenconazole 13.9%, Fluopyram 17.7% w/w + Tebuconazole 11.4% SC, Azoxystrobin 8.3% + Mancozeb 66.7% WDG and Pyraclostrobin 5% + Metiram 55% WG. Complete inhibition was achieved at 2000 and 4000 ppm with Triflumizole 42.14% SC and Azoxystrobin 18.2% + Difenoconazole 11.4% SC. Additionally, the liquid broth assay validated the efficacy of five fungicides in hindering mycelial dry weight. Furthermore, effective strategies against BSR, such as root feeding, stem injection and soil drenching, emerged as valuable insights for the integrated Ganoderma management in plantation crops.. KEYWORDS :Basal stem rot, fungicides, Ganoderma, management, oil palm

First Report of Fusarium pernambucanum Causing Fruit Rot of Melon in China.

In May of 2020, November of 2021 and May of 2022, a preharvest fruit rot with white mycelia was observed inside and outside of the fruits of thick skin muskmelon (Cucumis melo L.) growing in about ten greenhouses (each greenhouse had about 320 muskmelons) with disease incidence of 70% in Ningbo, Zhejiang Province of China. In order to identify the causal agent, plant tissues from the margin of the symptomatic tissue were sterilized for 1 min with 1% sodium hypochlorite (NaClO), 2 min with 75% ethyl alcohol, rinsed in sterile distilled water three times (Zhou et al 2019), and then placed on potato dextrose agar (PDA) plates containing streptomycin sulfate (100 μg/mL) at 25℃ for 4 days. Only Fusarium colonies were isolated from all the plant tissues. The growing hyphae were transferred to new PDA plates using the hyphal tip method, putative Fusarium colonies were purified by single-sporing. Six fungal isolates (Fi-1~6) were obtained. The average radial mycelial growth rate of Fusarium isolate Fi-3 was 4.6 mm/day at 25℃ in the dark on PDA, and like other five isolates. The colonies are abnormal, producing lots of aerial hyphae, each isolate was white to light orange. Isolate Fi-3 produced macroconidia with 4 to 6 septa, tapered with pronounced dorsiventral curvature and measured 21 to 30 μm long 4 to 5 μm wide on Spezieller Nährstoffarmer Agar (SNA) medium at 25℃ for 10 days (Leslie and Summerell 2006), but polyphialides and chlamydospores were still not available for 30 days. The pathogen species was further identified by translation elongation factor-1 alpha (EF-1α) sequencing. The EF-1α of six isolates were sequenced, and their EF-1α sequences were 100% identical to each other, and the sequence of strain Fi-3 was deposited in GenBank with accession no. OL782040 and was also compared with sequences in the FUSARIUM-ID database (Geiser et al. 2004), which indicated that it was 100% identical to those of F. pernambucanum strain NRRL 32864 (GenBank accession GQ505613), F. pernambucanum strain LC7040 (GenBank accession MK289626), and F. pernambucanum strain LC12149 (GenBank accession MK289588) within the Fusarium incarnatum - F. equiseti species complex 17 (FIESC17). Two phylogenetic trees were established based on the TEF1-α sequences of Fi-1~6 and other Fusarium spp., Fi-1~6 was clustered with the sequences of F. pernambucanum within the FIESC17. Thus, both morphological and molecular criteria supported identification of the strain as F. pernambucanum. A pathogenicity test was conducted to verify Koch's postulates, mycelium agar plugs (6 mm in diameter) were removed from the colony margin of a 3-day-old culture of strain Fi-3, healthy melon fruits were surface-sterilized with 70% ethanol and rinsed twice with sterile-distilled water. Then, the melons were wounded using a sterile inoculating needle to stab and inoculated by a mycelium agar plug of strain Fi-3 on the wound sites. 5 fruits were inoculated in each treatment, and a mycelium-free PDA plug was used as a negative control, repeated 3 times, at 25℃ with high relative humidity for 10 days. The results show disease symptoms similar to those naturally infected fruits on all inoculated melon fruits. The fungus re-isolated from the diseased fruits, showed the same colony morphology as the original isolate. Koch's postulates were repeated three times with the same results. Strain Fi-3 inoculated fruits without wounding remained healthy. To our knowledge, this is the first report of fruit rot of melon caused by F. pernambucanum in China.

The efficacy of chemical inducers and fungicides in controlling tomato root rot disease caused by Rhizoctoniasolani

Chitosan is an environmentally friendly natural substance that is used in crop disease management as an alternative to chemical pesticides. A significant issue restricting output in Egypt is root rot, which is a disease, caused by Rhizoctonia solani. Therefore, a greenhouse experiment was conducted to assess the effects of R. solani on 60-day-old tomato plants under fungal infection and to determine the antifungal activity of chitosan and Rizolax T fungicide against the pathogenic fungus. The findings demonstrated that 4 g/L of chitosan seed application completely obstructed the radial mycelial growth of R. solani and decreased the disease severity. Pathogenic infection significantly decreased morphological characteristics and total chlorophyll but significantly increased carotenoid, total thiol, non-protein thiol, protein thiol, antioxidant enzymes, oxidative stress, total phenolic, total flavonoid, and isoflavone compared to healthy plants. Tomato plants treated with chitosan exhibited lower rates of oxidative stress, but higher levels of all previously mentioned parameters compared to untreated infected plants. The number and molecular mass of protein banding patterns varied in all treated tomato plants as compared to the healthy control. There are 42 bands in the treatments, and their polymorphism rate is 69.55%. Moreover, the number and density of α- and β-esterase, and peroxidase isozymes in treated tomato plants exhibited varied responses. Moreover, in treated and control plants, chitosan treatment raised the expression levels of phenylalanine ammonia-lyase, pathogenesis-related protein-1, β-1,3-glucanases and chitinase. In conclusions, chitosan reduces R. solani infection by controlling the biochemical and molecular mechanisms in tomato plants during infection.

Lasiodiplodia iraniensis and Diaporthe spp. Are Associated with Twig Dieback and Fruit Stem-End Rot of Sweet Orange, Citrus sinensis, in Florida

Florida ranks among the most important citrus growing regions in the USA. The present study investigates the occurrence, diversity, and pathogenicity of fungal species associated with symptomatic sweet orange (Citrus sinensis) cv. Valencia plants and fruit. The survey was conducted on twigs and fruit collected in Southwest Florida during 2022. Based on morphological and molecular characteristics, the identified isolates belonged to the species Lasiodiplodia iraniensis, Diaporthe pseudomangiferae, and Diaporthe ueckerae. The pathogenicity of representative isolates was evaluated on citrus fruit and plants. Lasiodiplodia iraniensis was the most virulent on fruit and plants, followed by Diaporthe pseudomangiferae. Diaporthe ueckerae had the lowest virulence on fruit, and it was not pathogenic to plants. In vitro tests were performed to assess the effect of temperature on mycelial radial growth. The optimum temperature of growth ranged from 26.0 to 28.4 °C for all the evaluated species, and L. iraniensis showed the fastest mycelial growth. This study represents the first report of L. iraniensis as a causal agent of tree dieback and fruit stem-end rot on C. sinensis worldwide. Moreover, D. pseudomangiferae and D. ueckerae are reported here for the first time in association with citrus diseases worldwide.

Effect of Selected Leaf Extracts on the Mycelial Radial Growth of Phytophthora sp. Causing Corm Rot of Colocasia (Colocasia esculenta L.)

In the present study the pathogenicity of Phytophthora sp. causing corm rot of colocasia was proved by Koch’s postulates. Sixteen infected corm samples were collected from different markets in two districts (West Godavari and East Godavari) of Andhra Pradesh and pot experiment was carried out in the Department of Plant Pathology, SHUATS, Prayagraj during Rabi season (2022-23). Out of those, the sample which collected from Kovvur Rythu Bazar, West Godavari district in Andhra Pradesh shows high pathogenicity. Five leaf extracts viz., neem, mint, lantana, tulsi and periwinkle @ 5, 10 and 15% concentrations were evaluated by using poisoned food technique against Phytophthora sp. Among all the leaf extracts, neem leaf extract @ 5, 10 and 15% concentrations recorded minimum radial growth (26.43, 24.73 and 22.77 mm, respectively) and maximum per cent inhibition (33.27, 37.59 and 42.55%, respectively) of Phytophthora sp. at 120 hrs of incubation as compared to other leaf extracts, treated (Metalaxyl) and untreated checks. The present study is limited to one trial in Prayagraj conditions, therefore to substantiate the present results more such trials are required in future for further recommendation.

Antifungal Activity of Phyllospheric Bacteria Isolated from Coffea arabica against Hemileia vastatrix.

Peru is one of the leading countries that produce and export specialty coffees, favorably positioned in the international markets for its physical and organoleptic cup qualities. In recent years, yellow coffee rust caused by the phytopathogenic fungus Hemileia vastatrix stands out as one of the main phytosanitary diseases that affect coffee culture yields. Many studies have demonstrated bacteria antagonistic activity against a number of phytopathogen fungi. In this context, the aim of this work was to select and characterize phyllospheric bacteria isolated from Coffea arabica with antagonistic features against coffee rust to obtain biocontrollers. For that purpose, a total of 82 phyllospheric bacteria were isolated from two coffee leaf rust-susceptible varieties, typica and caturra roja, and one tolerant variety, catimor. Of all the isolates, 15% were endophytic and 85% were epiphytes. Among all the isolates, 14 were capable of inhibiting the mycelial radial growth of Mycena citricolor, and Colletotrichum sp. 16S rRNA gene sequence-based analysis showed that 9 isolates were related to Achromobacter insuavis, 2 were related to Luteibacter anthropi and 1 was related to Rodococcus ceridiohylli, Achromobacter marplatensis and Pseudomonas parafulva. A total of 7 representative bacteria of each group were selected based on their antagonistic activity and tested in germination inhibition assays of coffee rust uredinospores. The CRRFLT7 and TRFLT8 isolates showed a high inhibition percentage of urediniospores germination (81% and 82%, respectively), similar to that obtained with the chemical control (91%). An experimental field assay showed a good performance of both strains against rust damage too, making them a promising alternative for coffee leaf rust biocontrol.

Antifungal evaluation of turmeric rhizome extract against Colletotrichum capsici, the causal agent of anthracnose on red-chili peppers (Capsicum annum L.)

This study was conducted to evaluate the antifungal activity of the ethanolic extract of turmeric rhizome against Colletotrichum capsici Syd. and its efficacy in reducing anthracnose disease development on red chili peppers. The in vitro experiment aimed to determine the effect of the extract on inhibiting C. capsici growth in potato sucrose agar (PSA) medium incorporating the turmeric rhizome extract. The variables examined were mycelial growth, fungal sporulation, and spore germination. The in vivo experiment aimed to evaluate the effectiveness of the extract in reducing disease development on red chili peppers. The treatments were conducted using a completely randomized design with five concentration treatments and three replicates. The variables examined were radial mycelial growth zone diameter, fungal sporulation, spore germination, and disease intensity. Data were analyzed by analysis of variance, and the least significant difference was used for comparing means between treatments. The results of these experiments showed that ethanolic turmeric rhizome extract exhibited antifungal activity against C. capsici both in vitro and in vivo conditions. Turmeric rhizome extracts with concentrations of 1%, 2%, 3%, and 4% significantly inhibited mycelial growth, and even at a 4% concentration, C. capsici fungal colonies did not grow. Evaluation of the effect of the extract on fungal sporulation showed that inhibition occurred at a concentration of 3%, while inhibition of spore germination occurred at concentrations of 1%, 2%, and 3%. Application of turmeric extract at concentrations of 1%, 2%, 3%, and 4% effectively reduced the intensity of anthracnose on red chili.

Evaluation of Antifungal Activity of Plant Extracts against Papaya Anthracnose (Colletotrichum gloeosporioides) under In-vitro Condition

The study aimed to assess the effectiveness of various plant extracts against Colletotrichum gloeosporioides in papaya. This investigation employed a completely randomized design and took place at the College of Agriculture in Pune-05 during the academic year 2021-22.Among the six plant extracts tested, garlic (Allium sativum) was found to be superior to the rest, exhibiting the minimum mycelium growth (5.30 mm) and the highest percentage inhibition (94.11%) at a 20% concentration. However, the drumstick leaf (Moringa oleifera) extract was the least effective, with the maximum radial mycelial growth of 44.00 mm (51.11% inhibition) observed. The study indicates that the radial mycelial growth of Colletotrichum gloeosporioides decreases with rise in the concentration of plant extracts.

Compatibility of Metarhizium sp. (M201-NL strain) in Insecticide and Herbicide Mixtures

Field application of Metarhizium to control Oryctes rhinoceros in oil palm plantations may be overlapped with pesticides (insecticide and herbicide) spray. These chemicals may harm the fungus leading to poor virulence. This paper, however, shows that Metarhizium sp. M201-NL strain may react differently against some pesticides tested using poisoning media method. In the first experiment, the growth of mycelium of the Metarhizium sp. was observed in plated media mixed with insecticide. The highest mycelium radial growth was Fipronil 0.15 % (51.9 mm) which was not significantly different compared to the control, without insecticide (52.2 mm). However, suppression of growth of mycelium was observed in other insecticides. The radial growth of mycelium was significantly lower compared to the control if either Ethiprol, Lambdha cyhalothrin or Acephate was applied at 14 DAI. The second separate experiment involved herbicides. It was found that some herbicides did not inhibit the radial growth of mycelium. These include Metsulfuron-methyl 0.098 % (84.0 mm), Metsulfuron-methyl 0.19 % (82.75 mm), Glyphosate 19.6 % (82.5 mm), Glyphosate 9.8 % (81.6 mm) and Metsulfuron-methyl 0.39 % (80.37 mm) which were not significantly different compared to control, without herbicide (86.12 mm) at 21 DAI. In contrast, the growth of mycelium was significantly retarded when Paraquat, Triclopyr, Glyphosate, and 2.4-D was applied separately. Further study was undertaken to observe sporulation and virulence (bioassay) of the treated mycelium. The sporulations of mycelium treated with Fipronil 0.15 % or Metsulfuron-methyl of different concentrations were not statistically different to control. Similar results were also shown from bioassay. The infection rates of O. rhinoceros larva treated with mixtures of Metarhizium sp. spores with either Fipronil or Metsulfuron-methyl were insignificantly different compared to the control.

Evaluation of the antifungal effect of plant extracts on fungi associated with leaf spots on banana

Banana, a crop which constitutes one of the sources of income for the economy in Ecuador and other exporting countries. The objective of the research was to evaluate the antifungal activity of different plant extracts on the mycelial inhibition of Fusarium incarnatum in vitro. A completely randomized experimental design was used, with 21 treatments, 3 replicates and an absolute control. These treatments were plant extracts such as hydrolysates and ethanolic extracts: cinnamon (Cinnamomum verum), clove (Syzygium aromaticum) and oregano (Origanum vulgare) extracts. The variables evaluated were: radial growth of Fusarium incarnatum mycelium during the 7 days, area under the ABCPE disease curve and the value of the slope of the linear regression, the treatment that registered the greatest inhibition was T13, T14, T15 in all its doses (10,000; 30,000; 50,000 ppm) of the ethanolic extract of clove and T12 (50,000 ppm) of ethanolic extract of cinnamon. In conclusion, the ethanolic extracts at their above mentioned doses were the best treatments for inhibitory control at the in vitro level.

Antifungal potential of commercial silver nanoparticles against rice blast pathogen Magnaporthe oryzae

The rice blast caused by Magnaporthe oryzae is one of the major and recurrent threats to sustainable rice production in Bangladesh. To mitigate this problem, the present study was undertaken with the aim to investigate the inhibitory effects of commercially available silver nanoparticles (Ag-NPs) on the growth and development of Magnaporthe oryzae, and control of rice blast disease. In vitro experiments demonstrated that Ag-NPs significantly suppressed the radial growth of fungal mycelium, with the highest inhibition (83.54%) at a concentration of 250 ppm, while Trooper 75 WP at 400 ppm completely inhibited the fungal mycelial growth. The production of conidia and colony formation were also reduced significantly by Ag-NPs treatment. Furthermore, Ag-NPs exhibited a substantial inhibitory effect on the germination of M. oryzae conidia, with complete inhibition observed at concentrations between 200 and 250 ppm. Comparative analyses revealed that the fungicidal effect of Ag-NPs was superior to silver nitrate (AgNO3), suggesting the augmented activity of the nano properties. The sensitivity of M. oryzae to Ag-NPs was determined by calculating EC50 and EC95 values, which indicated a mean EC50 value of 131.5 ppm and a mean EC95 value of 276 ppm. Additionally, in vivo experiments showed that preventive and curative treatments with Ag-NPs significantly reduced disease incidence and severity in rice plants infected with M. oryzae, with efficacy comparable to that of the fungicide Trooper 75 WP. At higher concentrations of Ag-NPs, preventive treatment was found to be more effective than curative treatment in disease control. These findings highlighted the potential of Ag-NPs as an effective alternative for the management of rice blast. Ann. Bangladesh Agric. (2023) 27 (1): 17-30

Effect of Selected Leaf Extracts on the Mycelial Radial Growth of Phytophthora sp. Causing Corm Rot of Colocasia (Colocasia esculenta L.)

Effect of Selected Leaf Extracts on the Mycelial Radial Growth of Phytophthora sp. Causing Corm Rot of Colocasia (Colocasia esculenta L.)