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ABSTRACTIn the present study, five Penicilliumspecies, namely, P. italicum, P. expansum, P. simplicissimum, P. oxalicum, and P. citrinum, were identified using ITS (internal transcribed spacer) and β-tubulin markers and screened for their in vitro antagonistic potential against a soil-borne fungal pathogen, Macrophomina phaseolina, in a dual-culture plate assay. Among all the tested strains, P. italicumshowed the highest antagonistic potential against M. phaseolinaby reducing its growth up to 57% over control, followed by P. citrinum(42%), P. simplicissimum(21%), P. expansum(11%), and P. oxalicum(9%). In order to find out the mechanism of action of P. italicum, genomic DNA of M. phaseolinawas exposed to P. italicumsecondary metabolites. The findings showed that these metabolites completely degraded the fungal DNA after the 48-h incubation period. To further explore the antifungal mechanism of action of P. italicum, chloroform and ethyl acetate fractions of its metabolites were subjected to gas chromatography–mass spectrometry (GC-MS) analysis. The major compounds identified in these fractions were 9,12-octadecadienoic acid (Z,Z)- (25.19%), decane (19.72%), dodecane (18.05%), benzene, nitro- (14.62%), benzene, 1,3,5-trimethyl (14.37%), benzene, 1,4-diethyl (11.62%), 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester (9.02%), and 1-nonadecene (8.99%), which could be responsible for control of M. phaseolinagrowth.

The present study was carried out to evaluate the antagonistic efficacy of Aspergillus versicoloragainst the soil and seed inhibiting destructive plant pathogen Macrophomina phaseolina. The tested antagonist was confirmed by rDNA sequencing of ITS and β-tubulin genes with respective accession numbers MN719083 and MN736397. In dual culture bioassays, A. versicolorshowed potent antagonist activity and reduced the pathogen’s growth by 60% over control. To understand the mechanism of antagonistic fungus, DNA of the pathogenic fungus was incubated in secondary metabolites produced by the A. versicolorfor 24 and 48 h. After 48 h, metabolites of A. versicolorfully degraded the DNA of M. phaseolina. Moreover, for the identification of bioactive compounds, the chloroform and ethyl acetate fractions of A. versicolorculture filtrates were subjected to GC–MS analysis. A total of 10 compounds were identified in each of the two fractions. Among these, chondrillasterol (37.43%) followed by 1,2-benzedicarboxylic acid, diisooctyl ester (25.93%), decane (16.63%), 9,12-octadecadienoic acid (Z,Z)- (13.32%), stigmasterol (11.16%), undecane (10.93%), cis-1-chloro-9-octadecene (8.66%), benzene, 1,3,5-trimethyl (8.46%), and hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester (8.13%) were the major compounds. Some of the identified compounds are known to possess strong antifungal, antibacterial, nematicidal, and antioxidant properties. The present study concludes that A. versicoloris an effective antagonist against M. phaseolina.

The present study aimed to evaluate the antagonistic potential of Aspergillusspp. against Macrophomina phaseolina. All the tested species namely Aspergillus niger, Aspergillus terreus, Aspergillus flavipes, Aspergillus flavusand Aspergillus sydowiiwere identified by rDNA sequencing of ITS and β-tubulin regions prior to determine their antagonistic behaviour against the pathogen by using dual culture technique. A. flavipesproved to be the most effective in reducing the colony diameter of M. phaseolina(53%) followed by A. niger(41%) and A. flavus(37%) over control, whereas A. sydowiiand A. terreuswere the least effective with 6.2% and 5% in vitro biocontrol potentials, respectively. The secondary metabolites produced by A. flavipeswere tested against the genomic DNA of M. phaseolinato understand the mechanism of antagonism. The bioactive metabolites completely degraded the pathogenic fungal DNA at higher concentrations of 400% and 500% after 24 h. Moreover, the chloroform and ethyl acetate fractions of culture filtrates of A. flavipeswere subjected to GC–MS analysis for the identification of potential antimicrobial compounds and a total of 14 and 8 compounds were identified in these fractions, respectively. Among these 9,12-octadecadienoic acid (Z,Z)- followed by 1,2-benzedicarboxylic acid, diisooctyl ester; decane; hexadecanoic acid,2-hydroxy-1-(hydroxymethyl) ethyl ester; benzene, 1,2,3-trimethyl; n-hexadecanoic acid and naphthalene were the predominant compounds with peak areas of 31.72%, 26.27%, 18.47%, 10.62%, 6.82%, 6.04% and 5.67%, respectively. Literature shows that some of identified compounds possess antimicrobial properties, which might be responsible for control of M. phaseolina.

•Four potato cultivars (Ronoldo, Rubi, Challenge, and Sadaf) demonstrated robust resistance against the highly destructive Black Scurf disease, caused by Rhizoctonia solani.•The incidence of the disease displays a strong negative correlation with key physiological parameters, including chlorophyll levels, protein content, and enzyme activities, underscoring the detrimental impact of the disease on the overall health of potato plants.•Notably, enzymes such as catalase, peroxidase, and polyphenol oxidase exhibit significant alterations in their activity levels in response to the disease, signifying their potential utility as reliable indicators for identifying and characterizing resistant potato cultivars.

Southern blight or collar rot of bell pepper (Capsicum annuumL.) caused by Sclerotium rolfsiiSacc., is a serious disease that results in significant yield losses annually. A pot experiment was carried out for the management of this disease using dry biomass of Datura metel,a medicinal plant of the family Solanaceae. The soil was amended with 0.5, 1.0, …, 3.0% dry biomass of D. metelwith and without the inoculation of S. rolfsii. The highest disease incidence (100%) was recorded in the positive control where the soil was inoculated with S. rolfsiiwithout any soil amendment. The disease was completely controlled by 2% soil amendment. This soil amendment treatment enhanced bell pepper yield by 30% over the negative control (without any inoculation or amendment) and 136% over the positive control. Activities of defense-related enzymes namely polyphenol oxidase (PPO), peroxidase (POX), and phenylalanine ammonia lyase (PAL) were significantly increased in the positive control. However, the activities of these enzymes were significantly dropped due to the soil amendment with D. metel. This study concluded that the application of 2% dry biomass of D. metelcan control collar rot disease resulting in a significant increase in the yield of bell pepper.

Macrophomina phaseolina(Tassi) Goid is a destructive pathogen of cowpea that causes serious charcoal rot disease with significant yield losses. Antifungal activity of three indigenous Ascomycetes viz., Trichoderma harzianum, T. viride, and T. hamatum, and two Meliaceae members, i.e., Melia azedarachL. and Azadirachta indicaL. were assessed against the pathogen. Laboratory screening trials with cell-free culture filtrate showed the maximum reduction in growth of M. phaseolinawith T. harzianum,followed by T. viride. Various concentrations (1–5%) of methanolic leaf extract of A. indicashowed more reduction in fungal biomass than M. azedarach. Pot experiment was performed by T. harzianum, T. viride, and dry leaf biomass of A. indicaagainst M. phaseolina. Results revealed that potted soil amended with T. harzianumin combination with 1–3% dry leaf biomass of A. indicaheld a significant potential to decrease disease incidence to 20–25% and improve plant growth attributes up to fourfolds over positive control inoculated with M. phaseolinaonly. Physiology of the host plant was altered due to the incorporation of various soil amendments resulting in reduced activities of antioxidant enzymes (catalase, peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase). It was concluded that fungal antagonists and allelopathic chemicals would be an effective and eco-friendly means of managing the charcoal rot disease.

Bioassays were performed to assess the potential of Coronopus didymusfor managing collar rot disease of bell pepper, caused by Sclerotium rolfsii. In laboratory bioassays, methanolic shoot extract of C. didymuswas partitioned with n-hexane, chloroform, ethyl acetate and n-butanol. Concentrations from 3.125 to 200 mg ml− 1of each fraction were evaluated against the target fungal species. All concentrations of the ethyl acetate fraction gave complete inhibition of fungal growth. Thin layer chromatography of the ethyl acetate fraction yielded two unidentified compounds 1and 2with Rfvalues of 0.531 and 0.787, respectively. Antifungal activity of these compounds was assessed using the minimum inhibitory concentrations (MICs) technique. Mancozeb was used as a reference compound. Compound 2was found to be highly effective against S. rolfsiiwith MIC value 7.81 μg ml− 1which was at par with the MIC of mancozeb. In a pot trail, dried powdered shoots of C. didymuswere mixed at 1%, 2% and 3% (w/w) in soil already inoculated with the target fungal pathogen. A negative control with no fungal inoculation or soil amendment and a positive control with S. rolfsiiinoculation but no soil amendment were also included. The treatment with 3% soil amendment significantly suppressed the collar rot disease. There was 50% and 13% disease incidence and mortality, respectively, with 3% treatment compared with 91% and 40%, respectively, in the positive control. This study suggests that collar rot of bell pepper can effectively be managed by exploiting the antifungal potential of C. didymus.

Background: Sclerotium rolfsiiis a soil-borne fungal pathogen causing diseases in more than 500 plant species. It causes southern blight disease in chili. Chemical fungicides are used to control this disease, which also pollute the environment. The present study was designed to assess the potential of two species of plant-growth-promoting rhizobacteria (PGPR) viz. Bacillus megateriumand Pseudomonas fluorescence, and an allelopathic weed, Anagallis arvensisL., for the control of southern blight disease of chili. Results: Initially, three PGPR strains, viz. B. megateriumOSR3, B. megateriumZMR6, and P. fluorescencePF-097, were selected for their in vitro antagonistic assessment against S. rolfsiiby dual culture technique on potato dextrose agar medium. OSR3 showed the highest antagonistic potential (68%), followed by PF-097 (54%) and ZMR6 (33%).In a pot experiment, the two best strains of PGPR, namely OSR3 and PF-097, and dried biomass of A. arvensis(DBA) in different concentrations (1, 2 and 3%) were used to manage southern blight disease of chili.In positive control treatment (S. rolfsiionly), plant survival was low (73%) than the negative control (100%). OSR3, PF-097, OSR3 + 2% DBA, and PF-097 + 2% DBA significantly enhanced plant survival over positive control. The highest increase in chili growth over positive control was recorded due to OSR3, followed by PF-097 inoculations. Contents of carotenoid and chlorophyll were significantly decreased due to the fungal pathogen and improved due to PGPR strains. Application of the two PGPR strains and different concentrations of A. arvensisdistinctly increased the catalase (CAT), peroxidase (POX), and polyphenol peroxidase (PPO) activities over positive control. Conclusions: The present study concluded that PGPR strains B. megateriumOSR3 and P. fluorescencePF-097 can control southern blight disease effectively and increase growth and yield of chili.

Effective microorganisms are cultures of coexisting beneficial microorganisms predominantly consisting of species of photosynthetic and lactic acid bacteria, yeast and actinomycetes, that could be used for alternative crop production. I studied the effect of soil and foliar application of these microorganisms on crop growth, yield and nodulation in pea (Pisum sativum L.), in soils amended with Trifolium alexandrinum L. green manure, farmyard manure and NPK fertilizers. The results show that foliar application of effective microorganisms enhanced nodulation, using NPK amendment, reaching a 217% increase for nodule number and a 167% increase for nodule biomass. Similarly, a grain yield increase of 126% for NPK amendment and of 145% for green manure amendment was found after foliar application of effective microorganisms. These findings show that foliar application of effective microorganisms in combination with proper soil amendment can improve nodulation and yield in pea.

Background: Ascochyta blight caused by a fungal pathogen, Ascochyta rabiei, is a serious disease of chickpea in most chickpea growing areas of the world. The disease can be controlled by fungicides to reduce the environmental pollution. Main body: This study reports the control of Ascochyta blight by using extracts and dry biomass of a weed plant, Withania somnifera(Family Solanaceae). In a laboratory bioassay, a 0.2% concentration of methanolic leaf extract of W. somniferasignificantly inhibited the pathogenic fungal growth. Methanolic leaf extract was fractionated with 4 organic solvents of different polarities namely n-hexane, chloroform, ethyl acetate, and n-butanol. The effect of different concentrations (3.125, 6.25, 12.5, 25, 50, 100, 200 mg ml−1) of the 4 organic solvent fractions was assessed on in vitro growth of the pathogen. Among these, ethyl acetate and n-butanol fractions completely inhibited the fungal growth. Ethyl acetate fraction was further subjected to thin layer chromatography to separate the potent antifungal compounds A and B. Compound A was found highly effective against the targeted fungal pathogen with MIC 31.25 μg ml−1, followed by B with MIC value of 250 μg ml−1as compared to 7.81 μg ml−1MIC of a commercial fungicide mancozeb. In pot trial, the soil was amended by 1, 2, and 3% dry leaf material of the test plant species. Disease incidence was significantly reduced in 3% dose. Conclusions: This study concludes that W. somniferacontains potent antifungal compounds that can be effectively exploited for the control of A. rabiei.

Sclerotium rolfsiiis a soil-borne plant pathogen that causes root diseases in hundreds of plant species. It also causes collar rot disease in chickpea (Cicer arietinumL.). The present pot study was carried out to investigate the effect of soil amendment with dry biomass of a weed Chenopodium albumL. and two antagonistic fungi, namely Trichoderma harzianumand T. viride, on growth and yield of chickpea variety Noor 2009 in soil infected with S. rolfsii.The pathogen-contaminated soil was amended either with 1, 2, or 3% C. albumdry biomass, T. harzianum, and T. viridealone, or combinations of either of the two Trichodermaspecies and plant dry biomass. The lowest shoot and root dry biomass and grain yield of chickpea were recorded in S. rolfsiiinoculation alone without any soil amendment (positive control). Plant growth and yield were significantly and gradually increased over positive control with an increase in C. albumdry biomass application in the soil. Likewise, soil application of either of the two Trichodermaspecies significantly enhanced plant growth and yield over positive control under biotic stress of S. rolfsii.Combined application of either T. harzianumor T. viridewith 3% dry biomass of C. albumalso proved highly effective in alleviating biotic stress of S. rolfsiion growth and yield of chickpea.

Chickpea (Cicer arietinumL.) is an important grain legume that is attacked by the fungal pathogen, Sclerotium rolfsii, responsible for collar rot disease. In the present study, the pathogen was isolated from diseased chickpea seedlings and identified on molecular basis using internal transcribed spacer (ITS) and β-tubulin markers. To control this pathogen, an in vivo study was carried out, using Neem (Azadirachta indicaA. Juss.) leaf dry biomass (1, 2, and 3%) as soil amendment.A broad-spectrum fungicide mancozeb was selected as a reference and the data regarding plant growth and mortality rates were calculated. In positive control, the highest seedling mortality (56%) was recorded in comparison to negative control (0%) after 30 days of sowing. In 1, 2, and 3% concentrations of A. indicadry leaf biomass, the seedling mortalities were 49, 38, and 38%, respectively. On the other hand, the mancozeb-treated seedlings showed the lowest plant mortality rate (28%). Soil treatments with mancozeb as well as with 1 and 2% leaf biomass concentrations showed marked differences in root and shoot dry biomasses over positive control. In a laboratory bioassay, methanolic leaf extract of Neem of 0.5 to 3.5% concentrations reduced biomass of S. rolfsiiby 86–90% over control. The present study concluded that 2% A. indicaleaf amendment was the most useful concentration for management of collar rot disease of chickpea.