Application Of Biocontrol Agents Research Articles

A New Source of Inoculum for Stemphylium vesicarium: Consequences for the Management of Brown Spot of Pear

Brown spot of pear (BSP), caused by Stemphylium vesicarium, is one of the most dangerous pear fungal diseases, being responsible for huge losses in production. Currently, in order to increase its containment, chemical control is implemented in conjunction with agronomic techniques able to reduce BSP inoculum sources (e.g., orchard grass sanitation, litter removal or application of biocontrol agents). Regardless, despite the introduction of agronomic practices, the complete control of the disease is still rarely possible, which suggests that other sources of S. vesicarium inoculum that are currently neglected may be involved. The aim of this study is to investigate the possible wintering forms of Pleospora allii/S. vesicarium on pear wood and whether any spore-forming productions (conidial or ascosporic) might infect the green tissues of the plant in the following spring. Symptomatic fragments of woody tissue from a commercial pear orchard (in Ferrara, Emilia-Romagna, Italy) with a high BSP pressure (~40% incidence) were analysed. The results prove that pseudothecia and the maturation of ascospores of P. allii also develop on one-year-old branch cankers of pear trees, thus representing an additional source of inoculum. In conclusion, the pruning of affected branches and removal of relative residues should be preventatively performed in order to improve BSP management and control.

Profiling Metabolites with Antifungal Activities from Endophytic Plant-Beneficial Strains of Pseudomonas chlororaphis Isolated from Chamaecytisus albus (Hack.) Rothm.

Fungal phytopathogens represent a large and economically significant challenge to food production worldwide. Thus, the application of biocontrol agents can be an alternative. In the present study, we carried out biological, metabolomic, and genetic analyses of three endophytic isolates from nodules of Chamaecytisus albus, classified as Pseudomonas chlororaphis acting as antifungal agents. The efficiency of production of their diffusible and volatile antifungal compounds (VOCs) was verified in antagonistic assays with the use of soil-borne phytopathogens: B. cinerea, F. oxysporum, and S. sclerotiorum. Diffusible metabolites were identified using chromatographic and spectrometric analyses (HPTLC, GC-MS, and LC-MS/MS). The phzF, phzO, and prnC genes in the genomes of bacterial strains were confirmed by PCR. In turn, the plant growth promotion (PGP) properties (production of HCN, auxins, siderophores, and hydrolytic enzymes, phosphate solubilization) of pseudomonads were bioassayed. The data analysis showed that all tested strains have broad-range antifungal activity with varying degrees of antagonism. The most abundant bioactive compounds were phenazine derivatives: phenazine-1-carboxylic acid (PCA), 2-hydroxy-phenazine, and diketopiperazine derivatives as well as ortho-dialkyl-aromatic acids, pyrrolnitrin, siderophores, and HCN. The results indicate that the tested P. chlororaphis isolates exhibit characteristics of biocontrol organisms; therefore, they have potential to be used in sustainable agriculture and as commercial postharvest fungicides to be used in fruits and vegetables.

Efficacy of entomopathogenic nematodes in laboratory and field conditions of Cicer arietinum against cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

BackgroundThe chickpea Cicer arietinum (Fabaceae) field has suffered significant economic losses due to the presence of cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae). Attempts to control the larval population through chemical pesticides led to some reduction but also resulted in the development of resistance among the larvae. Consequently, the H. armigera population experienced a rapid resurgence in the field. Given the substantial losses caused by Helicoverpa larvae, there is now a growing interest in adopting eco-friendly methods for management. The application of biocontrol agents has emerged as a promising solution for effectively managing the infestation.ResultsIn the laboratory experiment, the entomopathogenic nematodes (EPNs) Steinernema pakistanense NNRC-NB.14, S. balochiense NNRC-NB.23, and S. abbasi NNRC-NB.33 were evaluated for their infectivity and mortality effects on mature cotton bollworm at various concentrations. The study demonstrated that the highest mortality rates were achieved at a concentration of 250 infective juveniles (IJs) per larva after 72 h. Steinernema pakistanense and S. balochiense exhibited higher mortality rates (95–98%) compared to S. abbasi (77%) at higher application concentrations. The field trial results reinforced the laboratory findings, demonstrating a significant decrease in H. armigera larval populations when employing EPN strains, particularly NNRC-NB.14 and NNRC-NB.33, compared to NNRC-NB.23. Despite the initial applications showing relatively low mortality percentages, the most effective larval control occurred after the third application of EPNs. The field trials revealed that, following the third spray, mortality percentages significantly increased from the initial range of 20–32% to a more substantial 70–90%. This cumulative impact highlights the importance of multiple applications in achieving optimal pest control.ConclusionThe findings of these studies highlight the promising potential of EPN as an eco-friendly and sustainable method for controlling the cotton bollworm. However, the successful implementation of EPN-based control strategies in agricultural systems requires careful consideration of factors such as nematode species selection, application methods, environmental conditions, and integration with other pest management practices. Further research is needed to optimize the efficacy and practicality of using EPN on a larger scale, addressing issues such as nematode production, formulation, and compatibility with existing farming practice.

Biocontrol agents modulate phyllosphere microbiota interactions against pathogen Pseudomonas syringae

The pathogen Pseudomonas syringae, responsible for a variety of diseases, poses a considerable threat to global crop yields. Emerging biocontrol strategies employ antagonistic microorganisms, utilizing phyllosphere microecology and systemic resistance to combat this disease. However, the interactions between phyllosphere microbial dynamics and the activation of the plant defense system remain poorly understood. Here we show significant alterations in phyllosphere microbiota structure and plant gene expression following the application of biocontrol agents. We reveal enhanced collaboration and integration of Sphingomonas and Methylobacterium within the microbial co-occurrence network. Notably, Sphingomonas inhibits P. syringae by disrupting pathogen chemotaxis and virulence. Additionally, both Sphingomonas and Methylobacterium activate plant defenses by upregulating pathogenesis-related gene expression through abscisic acid, ethylene, jasmonate acid, and salicylic acid signaling pathways. Our results highlighted that biocontrol agents promote plant health, from reconstructing beneficial microbial consortia to enhancing plant immunity. The findings enrich our comprehension of the synergistic interplays between phyllosphere microbiota and plant immunity, offering potential enhancements in biocontrol efficacy for crop protection.

Mosquito larvicidal bioassay with the fruit extracts of Diospyros kaki on filarial vector Culex quinquefasciatus

Due to the emergence of resistance of the commonly used synthetic pesticide, vector control is in grave danger. Application of biocontrol agents may be a suitable alternative approach in vector control. The purpose of this study was to evaluate the larvicidal effectiveness of crude and methanolic fruit extracts of Diospyros kaki against Culex quinquefasciatus, the carrier of human filarial worm. The methanol extract showed promising result in biocontrol assay than crude extract. The methanolic extract had the LC50 and LC90 values of 46 ppm and 186 ppm, respectively against 1st instar larvae after 72 hours of exposure, The rate of mortality was positively associated with the solvent extracts in increasing concentrations, having a regression coefficient value near to 1 in each case, showing a definite positive dose-dependent mortality. During chemical characterization of the solvent extract by GC-MS and FT-IR studies, some bioactive compounds like 5,8,11,14,17-Eicosapentaenoic Acid, Methyl 4,7,10,13,16,19-Docosahexaenoate, cyclotrisiloxane hexamethyl and Arsenous acid, tris(trimethylsilyl) ester were identified that showed the larvicidal activity against mosquito larvae either singly or jointly. Thus, D. kaki fruit extract showed excellent potential as a bio control agent for Cx. quinquefasciatus and the isolated bioactive phytochemical may be utilized as a source of a powerful insecticide.

Integration of mathematical modeling and target-based application of biocontrol agents for the control of Botrytis cinerea in vineyards.

Biocontrol agents (BCAs) are alternatives to synthetic fungicides with low risk to the environment and human health. Although several studies on the biocontrol of gray mold in vineyards have been performed, it is necessary to improve the usage of BCAs in fields conditions. Therefore, in the present study, BCAs were used both in calendar-based [based on four growth stages (GSs), i.e., flowering, pre-bunch closure, veraison, and before harvest] and predictive model-based strategies (only when Botrytis cinerea infection risk was predicted by the model). The BCAs applied during the seasons were selected considering the grapevine GSs. Treatments performed with BCAs were compared with synthetic fungicide treatments and an untreated control. The trials were conducted in three experimental vineyards with four epidemics. To evaluate the level of gray mold control of each treatment, disease severity was assessed at harvest and the presence of latent infection was evaluated. The integrative use of the predictive model and BCAs provided satisfactory levels of gray mold control, with gray mold severity levels significantly lower (P < 0.001) than those of the untreated control, which had severity values (< 7%) similar to those observed with synthetic fungicides following both calendar and model-based strategies. The integrative use of the predictive model and BCAs represents a valid alternative to conventional methods of gray mold control in vineyards, with more than 75% reduction in fungicide usage. © 2024 Society of Chemical Industry.

Winter Rye Cover Crops Shelter Competent Squash Phyllosphere Bacteria to Reduce Pseudomonas syringae pv. lachrymans Growth and Angular Leaf Spot Symptoms.

Cover crops, a soil conservation practice, can contribute to reducing disease pressure caused by Pseudomonas syringae, considered one of the most important bacterial plant pathogens. We recently demonstrated that the phyllosphere (leaf surface) bacterial community structure changed when squash (Cucurbita pepo) was grown with a rye (Secale cereale) cover crop treatment, followed by a decrease of angular leaf spot disease symptoms on squash caused by P. syringae pv.lachrymans. Application of biocontrol agents is a known agricultural practice to mitigate crop losses due to microbial disease. In this study, we tested the hypothesis that some phyllosphere bacteria promoted when squash is grown on cover crops could be isolated and used as a biocontrol agent to decrease angular leaf spot symptoms. We grew squash during a 2-year field experiment using four agricultural practices: bare soil, cover crops, chemically terminated cover crops, and plastic cover. We sampled squash leaves at three different dates each year and constructed a collection of cultivable bacterial strains isolated from squash leaves and rye cover crop material. Each isolated strain was identified by 16S rRNA gene sequencing and used in in vitro (Petri dish) pathogen growth and in vivo (greenhouse) symptom control assays. Four bacterial isolates belonging to the genera Pseudarthrobacter, Pseudomonas, Delftia, and Rhizobium were shown to inhibit P. syringae pv. lachrymans growth and angular leaf spot symptom development. Strikingly, the symptom control efficacy of all strains was stronger on older leaves. This study sheds light on the importance of bacterial isolation from cover crop sources to promote disease control. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Management of rice blast disease caused by Pyricularia oryzae through application of biocontrol agents and fungicides alone and in possible combinations

Management of rice blast disease caused by Pyricularia oryzae through application of biocontrol agents and fungicides alone and in possible combinations

Mitigating postharvest quantitative and qualitative losses in mango fruits through the application of biocontrol agents: An in-vivo and in-vitro assessment

Mango is a commercial fruit crop of India that suffers huge postharvest losses every year. The application of biocontrol agents (BCAs) bears a vast potential for managing the same, which is yet to be exploited to its fullest extent. Hence, studies were conducted for BCAs application of Debaryomyces hansenii, Bacillus subtilis and Pseudomonas fluorescens strains on mango fruit under in-vitro, in-vivo conditions to know the efficacy of these BCAs on the postharvest pathogen, shelf life and quality retention of mango fruit. The ‘poisoned food technique’ was attempted for in-vitro studies. For the in-vivo studies, fruit of the commercial cultivar ‘Amrapali’ were un-inoculated and pre-inoculated with major postharvest pathogens (anthracnose: Colletotrichum gloeosporioides and stem-end rot: Botryodiplodia theobromae) were treated with BCA, followed by ambient storage at (24 ± 4 °C, 75 ± 5 % RH). From the results, it has been observed that under in vitro studies, BCA Debaryomyces hansenii (Strain: KP006) and Bacillus subtilis (Strain: BJ0011) at the treatment level 108 CFU mL−1 while, the Pseudomonas fluorescens at 109 CFU mL−1 (Strain: BE0001) were significantly effective for pathogen inhibition. However, under the in vivo studies, the BCA Debaryomyces hansenii (Strain: KP006) at 108 CFU mL−1 treatment level was found to significantly reduce the pathogen's decay incidence while positively influencing the shelf life and biochemical (quality) attributes. This treatment increased the storage life of mango fruit by more than three days over control fruit. Therefore, BCA Debaryomyces hansenii (Strain: KP006) at 108 CFU mL−1 can be used to control the postharvest pathological loss of mango fruit without affecting its internal quality.

Application of Biocontrol Agents and Plants Extract Against Fungal Phytopathogens of Vegetable Crops

Application of Biocontrol Agents and Plants Extract Against Fungal Phytopathogens of Vegetable Crops

Management of Fusarium Wilt of Tomato (Fusarium oxysporum f. sp. lycopersici) and Related Soil-borne Diseases using Eco-friendly Methods: A Review

Tomato is rich in vitamins, minerals and contains anti-oxidant compounds, like vitamin C and lycopene that has significant role in human health as it has anti-cancer properties. Tomato production is significantly affected by several factors amongst which Fusarium Wilt is one of the major and widespread fungal soil borne diseases in Nigeria. Difficulty in controlling this disease is attributable to long survivability of the pathogen and its existence in diverse pathogenic races. Conventional strategies, such as the use of resistant cultivars and synthetic fungicides, are not completely effective in managing tomato wilt caused by Fusarium oxysporum f. sp. lycopersici and because of unintended effects of chemicals on the environments its application is highly cautioned. This paper has examined many non-pesticide approaches such as application of bio-control agents, use of suppressive soils, composts/vermicomposts and their extracts, animal manure and urine, soil solarization, botanical extracts, good agricultural practices and integrated disease management strategy to control Fusarium wilt and other related soil borne diseases. It is worth noting that no single method can effectively control such diseases. In order to achieve a sustainable and eco-friendly disease management strategy the use of integrated approach is highly recommended. This review will provide farmers with diverse methods to be integrated as management package for Fusarium wilt and related diseases.

Trunk Injection Delivery of Biocontrol Strains of Trichoderma spp. Effectively Suppresses Nut Rot by Gnomoniopsis castaneae in Chestnut (Castanea sativa Mill.).

Gnomoniopsis castaneae is responsible for brown or chalky nut rot in sweet chestnut (Castanea sativa), causing heavy reductions in nut production. Controlling it is challenging, due to its inconspicuous infections, erratic colonization of host tissues and endophytic lifestyle. Fungicides are not applicable because they are prohibited in chestnut forests and strongly discouraged in fruit chestnut groves. Trichoderma species are safe and wide-spectrum biocontrol agents (BCAs), with a variety of beneficial effects in plant protection. This study tested selected strains of T. viride, T. harzianum and T. atroviride for their ability to suppress G. castaneae. Field experiments were conducted in four chestnut groves (two test plots plus two controls) at two sites with a different microclimate. As the size of the trees were a major drawback for uniform and effective treatments, the Trichoderma strains were delivered directly by trunk injection, using the BITE® (Blade for Infusion in TrEes) endotherapic tool. The BCA application, repeated twice in two subsequent years, significantly reduced nut rot incidence, with a more marked, presumably cumulative, effect in the second year. Our data showed the tested Trichoderma strains retain great potential for the biological control of G. castaneae in chestnut groves. The exploitation of Trichoderma spp. as biopesticides is a novelty in the forestry sector and proves the benefits of these microbes in plant disease protection.

Antibacterial Activity and Mechanism of Three Root Exudates from Mulberry Seedlings against Ralstonia pseudosolanacearum.

Bacterial wilt is a significant soil-borne disease that poses a threat to mulberry production yield and quality of agricultural production worldwide. However, the disease resistance mechanisms dependent on root exudates are not well understood. In this present study, we investigated the antibacterial mechanisms of the main active substances (erucamide, oleamide, and camphor bromide) present in mulberry root exudates (MRE) against Ralstonia pseudosolanacearum (Rp), the causal agent of bacterial wilt. Our findings revealed that these three active substances inhibited the growth activity of Rp by affecting the cell morphology and extracellular polysaccharide content, as well as triggering a burst of reactive oxygen species. The active substances induced oxidative stress, leading to a decrease in Rp growth. Additionally, the expression levels of key genes in the hrp gene cluster (hrpB, hrpX, and hrpF) and other virulence-related genes (such as ripAW, ripAE, Rs5-4819, Rs5-4374, ace, egl3, and pehB) were significantly reduced upon treatment with the active substances. Further pathogenicity experiments demonstrated that root exudates (at a concentration of 1.5 mg·mL-1) delayed or slowed down the occurrence of bacterial wilt in mulberry. These findings provide valuable insight into the antimicrobial mechanisms of MRE against Rp and lay a theoretical foundation for the development and application of biocontrol agents to control mulberry bacterial wilt.

Optimizing Pre-Sowing Treatments for the Enhanced Growth, Fruit Yield, and Seed Quality in Abelmoschus esculentus L. Moench

This research investigated diverse pre-sowing techniques' impact on the growth, fruit, and seed yield of okra variety Arka Anamika. From fourteen treatments, seven were selected based on germination and vigour index for a subsequent field experiment. The Randomized Block Design trial with three replications revealed significant variations in growth and yield among pre-sowing treatments. The treatment employing PEG (Poly ethylene glycol) 6000-13.5% (-0.25MPa) for 6 hours exhibited the highest germination percentages. Pseudomonas fluorescens-10g/kg of seed also displayed notable performance. Treatment variations were observed in plant height, branches, and flowering timings. The results suggest that in terms of plant growth and flowering time, P. fluorescens was more effective than Trichoderma viride. P. fluorescens -10g/kg of seed, demonstrated superior results in achieving maximum seed yield parameters, ranking highest overall. T. viride-4g/kg of seed, emerged as the second most effective treatment. Recommendations for preserving seed quality included KNO3 2% for 6 hours and PEG 6000-13.5% (-0.25MPa) for 12 hours. Application of biocontrol agents, especially P. fluorescens and T. viride, markedly improved okra variety Arka Anamika's fruit and seed yield characteristics. The study concludes by emphasizing the benefits of biocontrol agents on overall performance and suggesting targeted treatments for optimal seed quality.

Mitigation of rice blast disease by using biocontrol agents and new molecular fungicides

Rice blast is one of the most devastating diseases which is caused by Pyricularia grisea. The disease infects the all growth stages of rice crop and causes severe yield loss. Biocontrol agents and new molecular fungicides were tested against blast disease of rice. Among the nine treatments tested, Seed treatment with Bacillus subtilis + Foliar spray of Tebuconazole 50% + Trifloxystrobin 25% WG @ 1g/l (T7) recorded the maximum (67.88 %) reduction of the blast disease followed by Seed treatment with Bacillus subtilis @10g/kg + Foliar spray of Picoxystrobin 6.78% + Tricyclazole 20.33% SC @1ml/l (T8) which recorded 58.67 % reduction of the blast disease. Combined application of biocontrol agents having ability to reduce rice blast disease and increase the yield significantly.

Establishment of Biocontrol Agents and Their Impact on Rhizosphere Microbiome and Induced Grapevine Defenses Are Highly Soil-Dependent

With a reduction in available chemical treatments, there is an increased interest in biological control of grapevine trunk diseases. Few studies have investigated the impact of introducing beneficial microorganisms in the rhizosphere on the existing indigenous soil microbiome. In this study, we explored the effect of two biocontrol agents (BCAs), Trichoderma atroviride SC1 (Ta SC1) (Vintec; Certis Belchim) and Bacillus subtilis PTA-271 (Bs PTA-271), on the grapevine rhizosphere bacterial and fungal microbiome as well as plant defense expression using high-throughput amplicon sequencing and quantitative real-time polymerase chain reaction (PCR), respectively. Additionally, we quantified both Ta SC1 and Bs PTA-271 in the rhizosphere over time using droplet digital PCR. The fungal microbiome was more affected by factors such as soil type, BCA treatment, and sampling time compared with the bacterial microbiome. Specifically, Ta SC1 application produced negative impacts on fungal diversity, whereas application of BCAs did not affect bacterial diversity. Interestingly, the survival and establishment of both BCAs showed opposite trends depending on the soil type, indicating that the physicochemical properties of soils have a role in BCA establishment. Fungal co-occurrence networks were less complex than bacterial networks but highly impacted by Ta SC1 application. Soils treated with Ta SC1 presented more complex and stable co-occurrence networks, with a higher number of positive correlations. Induced grapevine defenses also differed according to the soil, being more affected by BCA inoculation on sandy soil. The findings of this research emphasize the complex relationships among microorganisms in the rhizosphere and highlight the significance of taking into account various factors, such as soil type, sampling time, and BCA treatment, and their influence on the structure and dynamics of microbial communities.

Comparative evaluation of physiological and biochemical changes in black pepper plants infected by Colletotrichum siamense in response to Trichoderma viride and T. harzianum application

Black pepper (Piper nigrum L.) holds a prominent position as a globally renowned spice. Pepper vines are susceptible to various diseases, among which anthracnose stands out as a highly detrimental disease capable of severely affecting both foliage and berries. The current study was carried out to find out the effectiveness of Trichoderma viride and T. harzianum to manage the anthracnose disease of black pepper and to assess the plant innate defense response to these biocontrol agents application. Results demonstrated that foliar application of T. viride and T. harzianum, either individually or in combination, resulted in a significant reduction of disease incidence by 59.3, 67.2, and 69.8% respectively, compared to untreated infected plants. Additionally, disease severity was lowered to 71.1, 75.6, and 77.8% respectively in the treated groups. Simultaneously, these treatments exhibited a substantial promotion of black pepper growth, as indicated by increased leaf area index, number of leaves, shoot length and root length compared to the control. Physiological and biochemical analyses revealed a notable increase in chlorophyll (Chl a, Chl b, Total chl) and flavonoid content, coupled with reductions in hydrogen peroxide (H2O2), and Malondialdehyde concentrations at 48 and 96 h after treatment. Furthermore, evaluation of the superoxide dismutase (SOD) revealed a significant increase in SOD enzymatic activity following the application of the fungi, whether applied individually or in combination. Consequently, it was inferred that both T. viride and T. harzianum effectively protected black pepper plants from anthracnose by suppressing disease incidence, enhancing chlorophyll content, improving overall plant health, and inducing the innate defense system. These findings highlight the multifaceted advantages offered by T. viride and T. harzianum in terms of plant protection and growth promotion.

Novel moisture retaining dustable powder containing Steinernema abbasi effectively controls damage of subterranean termite in wheat and chickpea

The application of biocontrol agents in farm operations for pest control programs is gaining priority and preference globally. Effective delivery, infectivity of the biocontrol agents, and quality shelf-life products containing these bioagents are vital parameters responsible for the success of biopesticides under field conditions. In the present study, moisture-retaining bio-insecticidal dustable powder formulation (SaP) of Steinernema abbasi (Sa) infective juveniles (IJs) was developed and assessed for its shelf life, physicochemical profile, and bio-efficacy against subterranean termite under field conditions. Formulation exhibited free-flowing character, with pH of 6.50–7.50, and apparent density in the range 0.50–0.70 g cm−3. The bioefficacy study for two rabi seasons (2020–2021, and 2021–2022) in wheat and chickpea grown in an experimental farm heavily infested with subterranean termites (Odontotermes obesus) revealed a significant reduction in plant damage due to pest attack in formulation-treated plots, monitored in terms of relative number of infested tillers in wheat and infested plants in chickpea fields. The reduced damage to the crop caused by termite was reflected in the relative differences in the growth and yield attributes as well. The study establishes the potential of the developed product as a biopesticide suitable for organic farming and integrated pest management operations.

Strategic Management of Powdery Mildew of Grapes Using Fungicides and Bio-Control Agents

The study was carried out at ICAR-NRCG, Pune, Maharashtra, India during November–February of 2019–2020 and 2020–2021 to evaluate the bio-efficacy of fungicides and biocontrol agents and level of tolerance against powdery mildew of grapes. Total 18 treatments categorised into three groups were taken into account. Three groups viz. fungicides, biocontrol agents (Bacillus licheniformis, Trichoderma afroharzianum, Ampelomyces quisqualis) along with metrafenone and commercial formulations of biocontrol agents were analysed for disease control. A total of five applications of each treatment were made during the growing season. Results showed that, in case of Group I (registered fungicides), Hexaconazole 5 EC @ 1 ml l-1/ Difenoconazole 25 EC @ 0.5 ml l-1/Myclobutanil 10 WP @ 0.4 g l-1/Two sprays of sulphur @ 2 g l-1 was most effective in controlling the disease. In case of pure culture, Trichoderma afroharzanium had proved to be most effective in the control of powdery mildew when sprayed in alteration with Metrafenone. In Group III, alternate applications of commercial formulations of Bacillus subtilis (2 ml l-1), Trichoderma viridae (2 g l-1), Ampelomyces quisqualis (5 ml l-1) and sulphur (2 g l-1) was most effective in controlling the disease. It was concluded that the application of bio-control agents in alternation with chemical fungicides controlled the disease effectively.

Investigation on Management of Root-Knot Nematode, Meloidogyne incognita through Soil Application of Bio-control Agents in Field Pea

The pot experiment was conducted at AICRP on vegetables, Pusa farm, Dr. Rajendra Prasad Central Agricultural University during 2020-21. The bio-control agents viz. Glomus fasciculatum (85-90 spores/g), Trichoderma harzianum 1.0% WP (2×106 cfu/g), Pseudomonas fluorescens 1.0% WP (1×108 cfu/g), Purpureocillium lilacinum 1.0% WP (2×106 cfu/g) either singly or in combined application shown significant improvement in plant growth and development and in declining nematode population. The combined application of P. fluorescens 1.0% WP (1×108 cfug-1) and P. lilacinum 1.0% WP (2×106 cfug-1) when applied 10g per pot each is efficient in improving plant growth and on other hand, plants treated with Cartap hydrochloride 4G (5g per pot) had the lowest nematode population, galls per plant, and Reproduction factor (Rf). P. lilacinum 1.0% WP (2×106 cfu/g) demonstrated promising effects in plants when just single bio-control agent i.e., 10g/pot was used. This study discovered that utilizing a mixture of bio-control agents was more effective than using bio-control agents alone in reducing the population of M. incognita. According to the study, bio-control agents had the same effects as Cartap hydrochloride 4G. As a result, bio-control agents can be used instead of nematicides.