Bacterial Bioagents Research Articles

In vitro Evaluation on Efficacy of Bioagents and Plant Extracts against Early Blight of Tomato (Alternaria alternata)

AIMS: In vitro evaluation on efficacy of Bioagents and plant extracts against Early blight of tomato (Alternaria alternata) Study Design: CRD (Completely Randomized Design). Place and Duration of Study: A trial was conducted in plant pathology laboratory at HRS Venkataramannagudem, Dr. Y.S.R. Horticultural University, Venkataramannagudem, during 2022. Methodology: The efficacy of bioagents were tested against isolates for radial growth inhibition on suitable media (Potato dextrose media and Nutrient agar media) using dual culture technique under in vitro conditions. The poisoned food technique was followed to evaluate theefficacy of botanicals in inhibiting the mycelial growth of test pathogen. Results: In the present investigation total nine bioagents and four plants extracts were tested against Alternariaalternata under in vitro. Results revealed that among the nine antagonists., Trichoderma harzianum, Tichoderma viride, Tichoderma longibraciatum (TCT4), Trichoderma reesi (TCT10), A10 (Tichoderma asperellum), A28 (Trichoderma harzianum), Trichoderma virens and two bacterial bioagents Pesudomonas fluorescens and Baciilus subtillis tested against A. alternata, maximum reduction in colony growth of A. alternata was observed in A10 (T. asperellum) (69.50%) and significantly superior over all other bioagents tested which was followed by A28 (T. harzianum) (62.96%) and the next best was T. virens (60.28%). Least inhibition was noticed in Bacillus subtillis (46.69%). Total four plant extracts neem leaves (Azadirachta indica), onion bulb (Allium cepa), garlic bulb (Allium sativum), and turmeric rhizome (Curcuma longa) tested at three concentrations (5, 7.5, 10 %) with suitable control by poisoned food technique against A. alternata, onion bulb extract (44.07%) which was found superior to all other tested botanicals. Least mean per cent inhibition was recorded with turmeric (21.34%).

Bioprospecting of microbial agents and their metabolites as potential inhibitors of Phytophthora cinnamomi, the causal agent of avocado root rot

Phytophthora Root Rot (PRR) is one of the economically important diseases infecting avocado causing substantial yield losses worldwide. In this study, the root rot pathogen infecting avocado has been characterized and potential bioagents targeting PRR have been identified through molecular approaches. Field surveys revealed varying degrees of disease severity (54 %–17.5 %) and incidence (50 %–10 %) in Western Ghats of Tamil Nadu, India. The pathogen was isolated and identified as Phytophthora spp. based on morphology which depicted typical coralloid-type growth patterns. Besides, phylogenetic analysis with the ITS, ras-related protein and COX genes showed closed similarity with P. cinnamomi. The isolates showed significant variation in pathogenicity, with PC(TKI)-10 exhibiting the highest severity (70 %) developing typical symptoms. In vitro efficacy assays through dual-plate and volatiles revealed potential inhibitory effects of Trichoderma harzianum T (MP)-7 (81.11 %) and Bacillus amyloliquefaciens B (TI)-3 (76.67 %) against P. cinnamomi, and Scanning Electron Microscopy (SEM) provided insights into the antagonistic mechanisms, revealing physical interactions and enzymatic lysis of the pathogen by T (MP)-7 and B (TI)-3. Furthermore, Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified bioactive compounds in the crude extracts of these bioagents, elucidating their metabolic pathways and potential modes of action against P. cinnamomi. Our findings highlights the importance of P. cinnamomi in avocado and the mechanism of fungal and bacterial bioagents in the sustainable management of the disease.

Using Fungal and Bacterial Bioagent Formula Antagonists to Combat Fusarium Oxysporum f. sp. Lycopersici Under Greenhouse Conditions

Objective: This study aimed to test fungal and bacterial bioagents as formula antagonists of Fusarium oxysporum f. sp. lycopersici under greenhouse conditions. Methods: The fungal and bacterial formulations' shelf life under different temperatures as well as under growth chamber and greenhouse conditions, as well as their effects on biochemical alterations involved in the induction of plant defense against the causative pathogen were investigated. Results: In-vitro antagonist screening of bacterial and fungal isolates on radial growth, reduction and inhibition percentages revealed that T. harzianum exhibited 45.6% of inhibition followed by B. pumilus with 36.7%. Among the fungal and bacterial bio-agents, the highest effect on disease incidence and efficiency against pathogenic fungus under greenhouse conditions was B. pumilus 27 and 69%, respectively followed by T. harzianum 33 and 62% when applied before pathogen inoculation. Under greenhouse conditions, the effects of bio-fungicides also affected defense enzymes like peroxidase and polyphenol oxidase. The shelf life of the wettable powder formulation of bio-agents under different temperature was very important factor and established that the most suitable temperature for long term storage is 25 ºC for both B. pumilus and T. harzianum. Conclusion: Target application of disease control techniques in tomato plants demonstrated the efficacy of B. pumilus and T. harzianum in reducing Fusarium wilt. These results pave the way for the development of bio-agents that can replace fungicides in agriculture, offering a practical substitute.

In vitro Evaluation of Bio Control Agents and Botanicals against Mulberry Root Rot Pathogen Lasiodiplodia theobromae

Mulberry root rot is fast spreading disease caused by L. theobromae. The pathogen can be managed by synthetic fungicides. However, enormous use of synthetic fungicides leads to residual toxicity which affects the growth and development of silkworm. In this context, an attempt was made to use potential bio control agents for the management of this pathogen. Seven fungal and five bacterial bio agents evaluated out of them T. viride (Tv – B2), T. harzianum (Th - 44), B. subtilis (Bs - M) and (Bs - O) proved as best for inhibition of mycelial growth of the pathogen. Out of eleven botanical extracts used, garlic proved best at 15 per cent and 20 per cent and agave at 20 per cent concentration against root rot causing pathogen L. theobromae.

Compatibility of Commercial Polymers Used by the Seed Industry for Maize Biological Seed Coating

An efficient biological seed coating begins with the choice of a suitable polymer. Experiments were conducted at the Department of Seed Science and Technology, Professor Jayashankar Telangana State Agricultural University, Hyderabad, to determine the compatibility of commercial polymers and biocontrol agents. Five polymers commercially used by the seed industry were procured from seed companies. Three bioformulations were purchased from the commercial biofertilizer units and the pure cultures of Trichoderma viride, Pseudomonas fluorescens, and Bacillus subtilis were isolated from the bioformulations through serial dilutions, culturing and subculturing on microbial media. The compatibility of commercially used polymers has been tested with biocontrol agents using poisoned food technique (for fungal bioagents) and the inhibition zone technique (for bacterial bioagents). Observations on the reduction in radial growth of the fungal bioagent and zone of inhibition of bacterial bioagents was recorded in mm. The results revealed that all the 5 polymers commercially used by the seed industry were tested to show 96–100% compatibility with Trichoderma viride, 100% compatibility with Pseudomonas fluorescens, and 95–100% compatibility with Bacillus subtilis. These findings indicate that there is a greater compatibility of all the commercial polymers used in the seed industry with the bioagents which can also be used for effective seed coating with bioagents economically without incurring any additional inventory from the part of the industry.

Native bacterial bioagents for management of potato soft rot disease caused by Pectobacterium carotovorum subsp. carotovorum

BackgroundThe reduced rate of potato production may occur under different conditions such as field, transit, storage, and marketing. Potato cultivation is frequently affected by various pathogens, among which Pectobacterium carotovorum subsp. carotovorum is a notorious bacterial pathogen responsible for causing bacterial soft rot disease. This pathogen poses a significant threat to potato production worldwide, resulting in substantial economic losses and food security concerns. This study aimed to investigate the effectiveness of three bacterial bioagents, namely Brevundimonas bullata, Bacillus siamensis, and Bacillus velezensis, against P. carotovorum subsp. carotovorum, a notorious bacterium responsible for causing potato tuber soft rot disease.ResultsFifteen isolates were isolated from rhizosphere of potato plants. Out of 15 isolates, 3 isolates, No. 1, 11, and 12, showed highly antagonistic property to control the growth of P. carotovorum subsp. carotovorum in vitro. They were identified as B. bullata, B. velezensis, and B. siamensis, by using 16S rRNA nucleotide sequence analysis. Results from these experiments revealed that three bioagents exhibited notable inhibitory effects on the growth of the pathogenic bacterium. However, B. velezensis stood out as the most effective inhibitor among the tested bioagents, showcasing the highest level of bacteriostatic activity (2.6 cm). The findings from the in vitro experiments provided promising insights into the potential of these bacterial bioagents as natural antagonists against potato tuber soft rot disease. Building upon these promising results, the study recommended the utilization of all tested bioagents for controlling soft rot disease in potato tubers, especially during storage conditions where the risk of bacterial proliferation is heightened. Treatment with B. bullata, B. siamensis, and B. velezensis demonstrates varying degrees of efficacy in controlling the progression of soft rot disease. Notably, B. velezensis shows promising results with relatively low disease severity scores across all time points compared to the other treatments. B. velezensis demonstrates the lowest disease severity percentage at 7.00% compared to the other treatments.ConclusionsThe study underscores the significant potential of B. bullata, B. siamensis, and B. velezensis as effective biological control agents against potato tuber soft rot disease. By targeting the causative agent directly, these bioagents offer a promising avenue for mitigating the detrimental impact of soft rot disease on potato production, thereby contributing to improved crop yield and quality.

Biological Control of Tomato Bacterial Leaf Spots and Its Impact on Some Antioxidant Enzymes, Phenolic Compounds, and Pigment Content.

Tomato bacterial spots, caused by Xanthomonas campestris pv. vesicatoria (Xcv1) and X. euvesicatoria (Xe2), as well as bacterial specks, caused by two strains of Pseudomonas syringae pv. tomato (Pst1 and Pst2), represent significant threats to tomato production in the El-Sharkia governorate, often resulting in substantial yield losses. The objective of this study was to evaluate the efficacy of various biocontrol culture filtrates, including bacteria and fungi agents, in managing the occurrence and severity of these diseases, while also monitoring physiological changes in tomato leaves, including antioxidant enzymes, phenolics, and pigment content. The culture filtrates from examined Trichoderma species (T. viride, T. harzianum, and T. album), as well as the tested bacteria (Bacillus subtilis, Pseudomonas fluorescens, and Serratia marcescens) at concentrations of 25%, 50%, and 100%, significantly inhibited the proliferation of pathogenic bacteria In vitro. For the In vivo experiments, we used specific doses of 5 mL of spore suspension per plant for the fungal bioagents at a concentration of 2.5 × 107 spores/mL. The bacterial bioagents were applied as a 10 mL suspension per plant at a concentration of 1 × 108 CFU/mL. Spraying the culture filtrates of the tested bioagents two days before infection In vivo significantly reduced disease incidence and severity. Trichoderma viride exhibited the highest efficacy among the fungal bioagents, followed by T. harzianum and T. album. Meanwhile, the culture filtrate of B. subtilis emerged as the most potent among the bacterial bioagents, followed by P. fluorescens. Furthermore, applying these culture filtrates resulted in elevated levels of chitinase, peroxidase, and polyphenol oxidase activity. This effect extended to increased phenol contents, as well as chlorophyll a, chlorophyll b, and carotenoids in sprayed tomato plants compared to the control treatment. Overall, these findings underscore the potential of these biocontrol strategies to effectively mitigate disease incidence and severity while enhancing plant defense mechanisms and physiological parameters, thus offering promising avenues for sustainable disease management in tomato production.

Assessment of fungal and bacterial bioagents against Bipolaris sorokiniana inciting spot blotch on barley (Hordeum vulgare)

In India, spot blotch disease caused by Bipolaris sorokiniana is one of the major constraints in barley (Hordeum vulgare L.) production. The present study was carried out during 2022–23 at ICAR-Indian Agriculture Research Institute, New Delhi to identify promising biocontrol agents, which can act as eco-friendly alternatives to chemicals against Bipolaris sorokiniana inciting spot blotch on barley (Hordeum vulgare L.). In this study, 18 isolates of Trichoderma asperellum, 15 isolates of Trichoderma harzianum and 5 bacterial species were tested against B. sorokiniana under in vitro and in planta conditions. In the dual culture assays, Trichoderma asperellum 8686 and Trichoderma asperellum 8687 showed significantly highest per cent disease inhibition of 71.73% and 71.37% respectively. Among bacterial strains, Pseudomonas fluorescens and Bacillus amyloliquefaciens showed significantly good per cent disease inhibition of 64.09% and 57.09% respectively. B. subtilis and Pantoea spp. did not show any pathogen inhibition. In addition, the superior bioagents were also screened out. In the studies on in planta assays, Bacillus amyloliquefaciens (per cent disease control-55.19%) was found most effective for seed treatment against B. sorokiniana. Post-inoculation with biocontrol agents revealed that Bacillus amyloliquefaciens was at par with Trichoderma asperellum and Pseudomonas fluorescens against B. sorokiniana. Additionally, a combination of seed treatment, pre and post-inoculation treatment of biocontrol agents revealed that Bacillus amyloliquefaciens and Trichoderma asperellum 8686 were at par with Trichoderma harzianum (Pusa Th3) against B. sorokiniana. Overall, Bacillus amyloliquefaciens was more effective and consistent to manage spot blotch disease.

Ayçiçeğinde Sclerotinia sclerotiorum (Lib.) De Bary’ye Karşı Bazı Bakteriyel Antagonistlerin In vitro ve In vivo Etkinliklerinin Belirlenmesi

This study was carried out in 2017-2018 to determine the in vitro and in vivo activities of some bacterial bioagents against Sclerotinia sclerotiorum, which causes root and root-collar rot in sunflower cultivation areas of Konya and Aksaray provinces. Against the two most virulent S. sclerotiorum (Hırkatol and Eskil) isolates selected as a result of pathogenicity tests after being isolated and diagnosed from diseased plants which were collected from sunflower cultivation areas in Konya and Aksaray provinces, the antifungal effects of 16 bacterial isolates from the soil in the rhizosphere region of the healthy sunflower plants from the same areas were evaluated. Primarily, the most effective bacterial bioagents were determined by dual culture tests. As a result of the in vitro tests, a total of 5 bacterial isolates constituting the largest zone diameter were molecularly identified according to 16S rRNA and were used in pot experiments. The bacteria were identified as Bacillus cereus, Bacillus simplex, Brevibacterium frigoritolerans, Bacillus toyonensis (2 isolates) and were coded using the BLAST program of the GenBank database (NCBI). As per in vitro, the highest effect in both isolates of S. sclerotiorum was observed in Bacillus cereus and Bacillus simplex with an inhibition rate of 49.19-57.95%. Except for Bacillus toyonensis (B1), one of the bacterial species which were tested in vivo, all the bacteria reduced or stopped lesion development compared to the control. As a result of the application, the biological control agent completely prevented the growth of both the isolates of Bacillus cereus and Bacillus simplex S. sclerotiorum in in vivo conditions (100%). Efficacy studies have shown that bacterial isolates both cause healthy growth of sunflower plants and significantly prevent disease formation in treated plants when compared to control plants. These results emphasize the importance of such studies as a tool for the development of sustainable agricultural practices that can be easily applied in our region, and also show that B. cereus and B. simplex in sunflowers can be potential bacterial bioagents that can be used in biological control against S.sclerotiorum. In addition, it will be useful to carry out studies on the development of commercial preparations of the bacterial isolates found in the study.

Prospecting Efficacy of Native Bacterial Bioagents against Blast Disease and their Potential for Plant Growth Promotion in Finger Millet

Thirty-seven isolates of pseudomonas and bacillus were isolated from the phylloplane of healthy finger millet leaves. Two of the bacterial isolates showing maximum inhibition against the blast pathogen under invitro conditions were characterized by biochemical test and molecular characterization using 16SrRNA sequencing and also evaluated for hydrolytic enzyme activity under growth promotion activity. The isolates were identified to be Pseudomonas fluorescens (P-9) and Bacillus subtilis (B-10) showing 100% nucleotide similarity with reported strains. Field evaluation with microbial consortium (P-9 & B-10) as talc formulation resulted in significant reduction in leaf blast severity (55.15%), neck blast (44.44 %) and finger blast (46.02 % ) along with a 35.17 % increase in grain yield over control and highest cost benefit ratio of 1: 1.53 over control.

Management of Fusarium Wilt of Chickpea Using Integrated Approaches Leading Induced Systemic Resistance

The objective of the research was to investigate the impact of Trichoderma harzianum, Pseudomonas fluorescens, and Rhizobium, separately and together, on inducing systemic resistance in chickpea plants when exposed to Fusarium oxysporum f.sp ciceris. Various parameters such as wilt incidence, plant growth promotion, yield, peroxidase activity, polyphenol oxidase activity, and total phenol content were assessed after treating chickpea seeds (GNG-469) with these bioagents. The findings from in vitro experiments indicated that the treatment T14, which involved the combination of 1% T. harzianum, 2% P. fluorescens, and 2% Biochar, was the most potent combination of bioagents. Compared to the untreated control, this treatment considerably reduced wilt incidence and enhanced root length, shoot length, and overall yield. Furthermore, treatment T14 increased peroxidase activity by 1.4%, polyphenol oxidase activity by 1.6%, and total phenol content by 2.3% in chickpea plants during Fusarium wilt disease. These findings have crucial implications for creating innovative formulations utilizing fungal and bacterial bioagents to effectively control wilt disease in chickpea plants. Rhizobium exhibited the lowest growth inhibition (23.13%), and T. harzianum showed the highest growth inhibition (66.38%) in vitro compared to control. New generation fungicide such as Amistar top T5 (18%), the positive control, was highly effective against this soil-borne pathogen; however, chemical pesticides with hazardous implications must be replaced by ecofriendly biocontrol agents.. KEYWORDS :Systemic resistance, Chickpea wilt, Fusarium oxysporum ciceris, Biochar, Fungicides, Bioagents

Biological control of postharvest tomato fruit rots using Bacillus spp. and Pseudomonas spp.

BackgroundPostharvest diseases cause a wide loss to tomato fruits during handling and storing from harvest to consumers. Fungicides are mainly used to control postharvest diseases. Biological control is the eco-friendly substitute strategy used for postharvest diseases management as which becoming promise worldwide. Six bacterial bioagent (i.e., Bacillus subtilis, B. amyloliquefaciens, Pseudomonas resinovorans, P. alcaligenes, P. putida and P. stutzeri) were tested to suppress both Geotrichum candidum and Alternaria alternata causal agents of tomato fruit rots during storage.ResultsIn vitro, most of bioagents significantly reduced mycelial growth rate of G. candidum. Both of B. subtilis and P. stutzeri were the most superior bacterial bioagents with values 67.03 and 72.2%, respectively. In addition, B. subtilis and B. amyloliquefaciens resulted in the most superior over all antagonists against A. alternata. The lowest percent of disease incidence and severity of G. candidum were obtained by B. subtilis and P. stutzeri. The maximum reduction percent of it on tomato fruits was recorded by applying B. subtilis and P. stutzeri with values (90 and 87%) and (91, 89%) in both seasons, respectively. Also, the highest reduction of A. alternata was obtained by using B. subtilis, which resulted in 85 and 84% in both seasons, respectively. The application of bioagents against both pathogens was significantly improved fruit quality aspects (weight loss, vitamin C, TSS and acidity %) during storage period compared to infected control fruits.ConclusionThe findings revealed that both of B. subtilis and P. stutzeri could be potential biological control agents against most postharvest pathogens of tomato fruits. This might be an alternative control strategy instead of fungicides which service the sustainable and organic farming.

Antifungal exploitation of fungicides and bacterial bioagents against charcoal rot of chrysanthemum

Antifungal exploitation of fungicides and bacterial bioagents against charcoal rot of chrysanthemum

Effect on Hatching and Mortality of Root-knot Nematode (Meloidogyne javanica) by Bio-agents

Investigations were carried out in vitro condition to evaluate the antagonistic effect of fungal and bacterial bio-agents. For effective management of root-knot nematode experiment was conducted in laboratory condition using the culture filtrate (5, 10 and 20 percent concentrate) of bio-agents (viz., Trichoderma viride, Trichoderma harzianum, Purpureocillium lilacinum, Pochonia chlamydosporia and Pseudomonas fluorescens). Experimental results showed that all the tested bio-agents significantly reduced the percent hatched juveniles and increased the percent mortality of juveniles. Among the tested bio-agents T. viride was found most effective treatment with minimum percent hatched juveniles and maximum percent mortality on eggs and juveniles of Meloidogyne javanica.

Two Bacterial Bioagents Boost Onion Response to Stromatinia cepivora and Promote Growth and Yield via Enhancing the Antioxidant Defense System and Auxin Production

White rot, caused by Stromatinia cepivora (Anamorph: Sclerotium cepivorum Berk), is a serious soil-borne disease of the onion that restricts its cultivation and production worldwide. Herein, we isolated and characterized a plant growth-promoting rhizobacterium Stenotrophomonas maltophilia from healthy onion roots and an endophytic bacterium Serratia liquefaciens from healthy bean leaves. Both isolates showed strong fungistatic activity against S. cepivora using the dual culture and culture filtrate methods. This effect might be due to the presence of several volatile compounds, especially menthol in both culture filtrates as shown with a GC-MS analysis. Additionally, the root drench application of cell-free culture filtrates of S. maltophilia and S. liquefaciens significantly reduced the incidence and severity of white rot disease on treated onion plants, which was associated with the activation of both enzymatic (POX and PPO) and non-enzymatic (phenolics and flavonoids) antioxidant defense machineries of S. cepivora-infected onion plants. Moreover, the culture filtrates of both bacterial bioagents remarkably enhanced the growth (as expressed by root length, plant height, and number of leaves) and yield parameters (as indicated by bulb circumference, fresh weight of the bulb, and bulb yield per plot) of treated onion plants under field conditions during two successive seasons (2020/2021 and 2021/2022). This might be because of a reduced disease severity and/or the accumulation of the main auxin, indole-3-acetic acid (IAA), and its precursor, the amino acid tryptophan. Our findings suggest that both bioagents might be utilized as eco-friendly alternative control measures to reduce the utilization of chemical fungicides entirely or partially for the safer production of onion in S. cepivora-infested soils.

Fungal and Bacterial Bioagents Efficiency on the Control of Potato Pest Phthorimaea operculella via Ingestion or Contact

Potatoes are one of the most important food products in the world and considered a main human nutrition sources source. Potato tuber moth (Phthorimaea operculella Zeller (PTM) (Lepidoptera: Gelechiidae)) causes remarkable economic losses to important crop, both in field and under storage conditions In this study, the insecticidal efficiency of the following bioagents: Brevibacillus brevis (FD-1), Bacillus atrophaeus (FD 17), Bacillus sphaericus (FD 49), Bacillus cereus (FD 63), Vibrio hollisae (FD 70), Bacillus thuringiensis subsp. kenyae (FDP 8) bacteria strains and Beauveria bassiana fungal isolate (ET 10), were evaluated on their efficacy to control P. operculella, under controlled conditions. In addition to insecticidal efficacy evaluations, analyses were also carried out to determine the differences between bioagents action mode: (1) uptake (ingestion as a gastric poison) and (2) contact. For (1), 20 larvae were fed on the tubers immersed in these suspensions to analyze efficacy by ingestion; for (2), suspensions of 1x108 CFU/ml of bacteria and 5.7x105 conidia/ml of fungus were prepared and sprayed to 20 larvae. FD-63 (91.67%) and FD-17 (88.33%) taken up by diet gave the most effective results against the pest.

<i>In Vitro</i> Evaluation of Bacterial Bioagents against <i>Colletotrichum gloeosporioides</i> Causing Anthracnose in Grape

Grape (Vitis vinifera L.) is an important fruit crop cultivated all over the world. Anthracnose of grapes is one of the contributing factors to low productivity. Therefore, the eco-friendly and environmentally safe management of anthracnose disease with the use of bioagents is necessary. Several bacterial bioagents evaluated under in vitro conditions against the mycelial growth of Colletotrichum gloeosporioides revealed that bacterial bioagents viz., UHSBS-1 showed maximum inhibition of mycelial growth followed by UHSBS-9 and UHSBS-21 isolates of Bacillus subtilis. Least inhibition was observed by UHSPF-2 isolate of Pseudomonas fluorescens under laboratory dual culture technique.

Biological Control of Groundnut Stem Rot and Collar Rot Pathogens under in vitro Conditions

The experiment was conducted under laboratory conditions by using native isolates. These were tested against stem rot (S. rolfsii) and collar rot (A. niger) pathogens of groundnut under in vitro conditions by using dual culture technique. The fungal and bacterial bioagents which are inhibitory against these pathogens were identified by 18S rRNA (fungi) and 16S rRNA (bacteria) techniques and were compared with those from the GenBank using the BLAST program. Among fungal isolates T. harzianum (MBNRT-1) was superior in inhibition of S. rolfsii and A. niger and the per cent inhibitions were 70.5% in case S. rolfsii whereas; in A. niger the inhibition was 72.9 per cent. Among native bacterial isolates the isolate B. amyloliquifaciens (MBNRB-3) and is significantly superior over the other isolates in inhibiting the pathogens S. rolfsii and A. niger under in vitro conditions and the inhibitions were 66.6 per cent and 63.0 per cent respectively. Further, compatibility of effective fungal and bacterial bioagents T. harzianum (MBNRT-1) and B. amyloliquifaciens (MBNRB-3) with six fungicides and eight herbicides indicated that among the fungicides the azoxystrobin was highly compatible with both the bioagents T. harzianum (MBNRT-1) and B. amyloliquifaciens (MBNRB-3) whereas, among the herbicides imazethapyr + imazamox was found to be compatible with both the bioagents with all the concentrations. While, tebuconazole, thiram, mancozeb+carbendazim (fungicides) and quizolofop-p-ethyl and pendimethalin (herbicides) were highly inhibitory to the T. harzianum (MBNRT-1) and B. amyloliquifaciens (MBNRB-3) under in vitro conditions.

Combined Application Of Fungal And Bacterial Bioagents, Together With Fungicide For Integrated Management Of Stem Rot Disease Of Groundnut

Combined Application Of Fungal And Bacterial Bioagents, Together With Fungicide For Integrated Management Of Stem Rot Disease Of Groundnut

THE COMPLEX EFFECT OF A MIXTURE OF SAPROTROPHIC BACTERIAL STRAINS ON GARDEN STRAWBERRIES DURING PRE-PLANTING PROCESSING

The studies were carried out in field experiments in 2014-2017 with the aim of a comprehensive assessment of the action of bacterial bioagents on garden strawberry plants in the conditions of a production mother liquor. It has been established that preplant treatment of strawberry seedlings with a suspension of a mixture of strains of saprotrophic bacteria of the genus Bacillus (B. amyloliquefaciens VKPM V-10642, B. amyloliquefaciens VKPM V-10643, B. subtilis VKPM V-10641) in equal proportions, at a concentration of 1×105 CFU/ ml) increased their survival by an average of 20.5% relative to the control, providing a pronounced antistress effect. The degree of damage to strawberry leaves with white spotting decreased by 1.2-1.8 times due to the immunizing effect of the drug. Treatment with a mixture of bacterial strains stimulated an increase in the length of the aerial part by 15%, the length of the root system - by 19%, the biomass of strawberry plants - by 20%, as well as vegetative propagation of strawberries - the number of daughter rosettes increased by 31.8%. The preparative mixture of bacterial strains has a multifunctional effect on plants and is a promising tool for expanding the arsenal of biological methods to increase the efficiency and environmental stabilization of the production of strawberry planting material.