Combination Of Biocontrol Agents Research Articles

Combined application of the endophyte Bacillus K1 and sodium dehydroacetate alleviates postharvest gray mold in grapes

Botrytis cinerea, which causes postharvest gray mold, is a primary pathogen that limits grape shelf-life and consumption and causes substantial yield loss worldwide. The combined use of biocontrol agents and food additives has attracted increasing interest. The effects of combined treatment with the endophyte Bacillus subtilis K1 and sodium dehydroacetate (SD) on the occurrence of gray mold and maintenance of grape fruit quality were studied. Treatment with a K1 suspension (1 × 108 CFU/ml) combined with 0.32 g/L SD resulted in markedly improved control of B. cinerea on grapes. The disease incidence and severity in the groups treated with K1 alone or in combination with SD were significantly lower than those in the control groups (P < 0.05) when the mixtures were applied 2 h after pathogen inoculation. Moreover, application of the mixture could maintain the appearance, firmness, total soluble solid (TSS) content and titratable acidity (TA) of grape fruit. Furthermore, the combination triggered increases in the activities of defense-related enzymes such as peroxidase (POD), phenylalanine ammonia lyase (PAL), catalase (CAT), superoxide dismutase (SOD) and polyphenol oxidase (PPO). Additionally, it could increase the vitamin C content. Thus, appropriate combinations of biocontrol agents and chemical reagents can provide effective protection against postharvest decay.

Expression of FUB-1 and FUB-11 as Toxic genes responsible for virulence during pathogenesis and combination of biocontrol agents in inhibition of Fusaric acid of Fusarium oxysporum causing Fusarium wilt of Arachis hypogaea L.

Expression of FUB-1 and FUB-11 as Toxic genes responsible for virulence during pathogenesis and combination of biocontrol agents in inhibition of Fusaric acid of Fusarium oxysporum causing Fusarium wilt of Arachis hypogaea L.

Biocontrol in practice in Canadian floricultural greenhouses

Abstract The environment inside Canadian prairie greenhouses differs from greenhouses built in other northern latitude locations in terms of lighting, temperature, humidity, and photoperiod. Since the performance of biocontrol agents depends upon several interactive environmental variables, their effectiveness to control pests in a particular crop growing under certain climatic conditions does not directly translate to another crop or location. So, we analyzed research trials assessing the efficacy and compatibility of various biocontrol agents (Amblyseius cucumeris, Amblyseius cucumeris, Phytoseiulus persimilis, Encarsia formosa, Aphidius colemani, Aphidius ervi, and Steinernema feltiae) on key pests (Western flower thrips, two-spotted spider mites, greenhouse whiteflies, and aphids) of spring bedding plants grown in a commercial floricultural greenhouse. Were analyzed several compatible combinations of biocontrol agents and observed a significant reduction in pest densities and plant damage symptoms as compared to untreated control plants. The results demonstrate that P. persimilis controlled two-spotted spider mites successfully in calibrachoa crop. The combination of Amblyseius cucumeris and S. feltiae resulted in significantly better control of Western flower thrips than the use of Amblyseius cucumeris alone in sweet potato vine plants. The application of E. formosa and Amblyseius cucumeris individually reduced greenhouse whiteflies on calibrachoa plants as compared to control, but their combination performed better resulting in a significantly lower number of whiteflies on plants. Another combination of Aphidius colemani and Aphidius ervi controlled green peach aphids and foxglove aphids effectively on the pansy crop. The biocontrol agents were effective for managing a variety of pests in a commercial greenhouse setting.

The combination of two Bacillus strains suppresses Meloidogyne incognita and fungal pathogens, but does not enhance plant growth.

The combination of biocontrol agents is a desirable strategy to improve control efficacy against the root-knot nematode (RKN) Meloidogyne incognita under field conditions. However, strains compatibility is generally tested in vitro and incompatible combinations are normally not further examined in experiments in planta. Therefore, there is virtually no information on the performance of incompatible strains. In this study, we evaluated two Bacillus strains previously described as incompatible in vitro for effects on plant growth and suppression of M. incognita, pathogenic fungi and nematophagous fungi. Strains BMH and INV were shown to be closely related to Bacillus velezensis. These strains, when applied individually, reduced the number of galls and eggs of M. incognita by more than 90% in tomato roots. When BMH and INV were combined (BMH + INV), RKN suppression and tomato shoot weight were lower compared to single-strain applications. Additionally, metabolites in cell-free supernatants and volatile organic compounds (VOCs) from strains BMH and INV had strong effects against the plant pathogens M. incognita, Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsiii, but not against three species of nematophagous fungi. Although strain INV and the combination BMH + INV emitted fewer VOCs than strain BMH, they were still capable of killing second-stage juveniles of M. incognita. Bacillus strains BMH and INV inhibited M. incognita and fungal pathogens, and promoted tomato growth. However, strain INV emitted fewer VOCs and the combination BMH + INV did not enhance the activity of the biocontrol strains against the RKN or their capacity to promote plant growth. © 2021 Society of Chemical Industry.

Effective In Vitro Control of Two Phytopathogens of Agricultural Interest Using Cell-Free Extracts of Pseudomonas fluorescens and Chitosan.

A biofungicide is a natural product that can be derived from various sources such as, among others, microorganisms, higher plants, animal products, phytochemicals, semiochemicals, and antagonist microorganisms. One of the most important approaches for the production of biofungicides is the combination of biocontrol agents. This study showed the inhibition growth of Alternaria alternata and Fusarium solani treated with cell-free extracts of P. fluorescens. Using thin-layer chromatography and plate assays it was also demonstrated that the cell-free extracts of P. fluorescens contained siderophores and derivates of 4-diacetylphloroglucinol and phenazine. Moreover, the combination of cell-free extracts of P. fluorescens and chitosan [50–1.5% (v/v)] had a synergistic effect since they notably inhibited the mycelial growth of A. altenata and F. solani. Various morphological alterations to the mycelia and conidia of the treated fungi as a result of this combination were also observed. The present study could be a starting point to control other fungal phytopathogens using different cell-free extracts and chitosan as biocontrol agents.

Dissemination of Isaria fumosorosea Spores by Steinernema feltiae and Heterorhabditis bacteriophora.

Entomopathogenic nematodes and fungi are globally distributed soil organisms that are frequently used as bioagents in biological control and integrated pest management. Many studies have demonstrated that the combination of biocontrol agents can increase their efficacy against target hosts. In our study, we focused on another potential benefit of the synergy of two species of nematodes, Steinernema feltiae and Heterorhabditis bacteriophora, and the fungus Isaria fumosorosea. According to our hypothesis, these nematodes may be able to disseminate this fungus into the environment. To test this hypothesis, we studied fungal dispersal by the nematodes in different arenas, including potato dextrose agar (PDA) plates, sand heaps, sand barriers, and glass tubes filled with soil. The results of our study showed, for the first time, that the spreading of both conidia and blastospores of I. fumosorosea is significantly enhanced by the presence of entomopathogenic nematodes, but the efficacy of dissemination is negatively influenced by the heterogeneity of the testing arena. We also found that H. bacteriophora spread fungi more effectively than S. feltiae. This phenomenon could be explained by the differences in the presence and persistence of second-stage cuticles or by different foraging behavior. Finally, we observed that blastospores are disseminated more effectively than conidia, which might be due to the different adherence of these spores (conidia are hydrophobic, while blastospores are hydrophilic). The obtained results showed that entomopathogenic nematodes (EPNs) can enhance the efficiency of fungal dispersal.

Enhancing Biocontrol Agents by Hydroquinone and Salicylic Acid for Controlling Root-Rot and Wilt Diseases of Lupine

Utilization of Trichoderma harzianum and Bacillus subtilis as biocontrol agents and chemical inducers hydroquinone (HQ) and salicylic acid (SA) as plant systemic inducers resistance individually or in combinations was studied for controlling root rot and wilt diseases and growth promoting of lupine plants in vitro and in vivo. Both antagonistic bioagents and chemical inducers either individually or in combination inhibited linear growth of Fusarium oxysporum f.sp. lupini and Rhizoctonia solani with variable degrees compared to the check. Bacillus subtilis + HQ and B. subtilis + SA recorded the highest reduction of mycelial growth in both pathogenic fungi. Under the greenhouse and field conditions, all treatments significantly reduced damping-off and root rot/wilt incidence and increased the survived plants. The combination of biocontrol agents and chemical resistance inducers were more effective than using each of them individually. Also, under field conditions, these treatments significantly increased plant growth parameters and yield components in both locations (Ismailia and Sers El-layian Res. Stations Farms during 2017/2018 growing season). In physiological studies, photosynthetic pigments, activities of defense-related enzymes, including peroxidase (PO), polyphenoloxidase (PPO) and total phenols content (TPC) were increased in plants treated with biocontrol agents combined with chemical inducers compared to using each of them individually. Generally, the combination of biocontrol agents and chemical resistance inducers recorded the best results for controlling damping-off, root rot/wilt diseases, plant growth parameters and yield components in the greenhouse and field. Such these treatments may be used as a part of integrated disease management for field crops in order to avoid the use of fungicides.

Combination of Trichoderma viride and Pseudomonas fluorescens for the enhanced control of Fusarium wilt disease caused by Fusarium oxysporum infecting Arachis hypogaea L.

Fusarium wilt caused by Fusarium oxysporum is a devastating disease of peanut. The fungus causes severe yield loss in groundnut. Combinations of biocontrol agents that are compatible with each other is a viable approach to control the plant disease. The study was conducted to determine the beneficiary aspects of combining different species of Trichoderma and Pseudomonasfluorescens i.e Trichoderma viride+Pseudomonas fluorescens (Tv+Pf), Trichoderma harzianum+Pseudomonas fluorescens (Th+Pf) and Trichoderma viride +Trichoderma harzianum (Tv+Th) to control the Fusarium wilt in biochemicalparameters such as DNA, RNA, Amino nitrogen, phenols, dihydroxy and proline contents of Arachis hypogaea.L. Among the three combinations tested, Trichoderma viride + Pseudomonas fluorescens (1+2%) sprayed leaves provided greater suppression of Fusariumoxysporum by increasing the levels of DNA,RNA,Amino nitrogen contents resulting in the suppression of Fusarium wilt disease of Arachis hypogaea L.Maximum reduction of DNA, RNA, Amino nitrogen was observed in the infected Fusariumoxysporumleaves Phenol, Dihydroxy phenols and proline contents increase sharply in the treated plants treated with (Tv+Pf) as compared to the control plants. At the same time the other two combinations resulted in enhanced control in comparison with individual ones. This present study indicates that specific combination of Trichoderma viride and Pseudomonas fluorescens could have the greater efficacy in the inhibition of pathogen in the biocontrol of Fusarium wilt disease as compared with individual strains.

Combinatorial efficacy of Trichoderma spp. and Pseudomonas fluorescens to enhance suppression of cell wall degrading enzymes produced by Fusarium wilt of Arachis hypogaea.L

Fusarium oxysporum, the soil borne pathogen causes vascular wilt, on majority of crop plants. It has been demonstrated that two different species of Trichoderma and Pseudomonas fluorescens suppress disease by different mechanisms. Therefore, application of a mixture of these biocontrol agents, and thus of several suppressive mechanisms, may represent a viable control strategy. A necessity for biocontrol by combinations of biocontrol agents can be the compatibility of the co-inoculated micro-organisms. Hence, compatibility between Trichoderma spp. and Pseudomonas fluorescens that have the ability to suppress Fusarium oxysporum in vitro on the activity of pectinolytic enzymes of Fusarium oxysporum. The activity of pectinolytic enzymes, i.e. pectin methyl esterase, endo and exo polymethylgalacturonases and exo and endo pectin trans eliminases produced by Fusarium oxysporum (Control) was higher. Maximum inhibition of pectin methylesterase, exo and endo polymethylgalacturonase and exo and endopectin trans eliminase was shown by culture filtrate of Trichoderma viride + Pseudomonas fluorescens (Tv+Pf) (1+2%), followed by Trichoderma harzianum + Pseudomonas fluorescens, (Th +Pf) (1.5+2%) and Trichoderma viride + Trichoderma harzianum (Tv+Th) (1+1.5%). However, pathogenecity suppression of Fusarium oxysporum, a causative of Arachis hypogaea. L by the compatible combination of Trichodema viride + Pseudomonas fluorescens (1+2%) was significantly better as compared to the single bio-agent. This indicates that specific interactions between biocontrol agents influence suppression of pathogenicity factors directly by combinations of these compatible bio-agents.Int. J. Agril. Res. Innov. &amp; Tech. 7 (2): 36-42, December, 2017

Rapid and sensitive method for detection of Staphylococcus aureus enterotoxin genes in milk sample

Expression of FUB-1 and FUB-11 as Toxic genes responsible for virulence during pathogenesis and combination of biocontrol agents in inhibition of Fusaric acid of Fusarium oxysporum causing Fusarium wilt of Arachis hypogaea L.Pilli Rajeswari

Use of biocontrol agents in combination with physical and chemical treatments: efficacy assessment

Purpose of review: This review discusses the combination of biological control agents with physical (heat, gamma or UV-C irradiation, controlled atmosphere) or chemical (salt additives, chitosan, natural plant products) treatments against the main postharvest fruit diseases. Findings: The use of biocontrol agents (BCAs) to control postharvest fruit diseases is still constrained by the lack of high levels of disease control required in the postharvest phase (more than 95%). Their inconsistent activity is one of the main factors preventing their routine application on fruit after harvest. Therefore, to overcome this issue, integrated strategies were explored and continue to be one of the fields most investigated in postharvest fruit disease control, in order to achieve maximum effectiveness. The combination of BCAs with physical and chemical treatments, including fungicides at low doses, resulted in an increase of BCAs effectiveness against fungal diseases such as Pencillium spp., Monilinia spp., Botrytis cinerea , etc. Since the integration of different treatments could benefit from their additive or synergic effects and improve the efficacy of each single method. Limitations: It is unrealistic to assume that BCAs have the same fungicidal activity as pesticides; the evaluation of their compatibility with other methods therefore seems to be the main topic that will be developed in the near future. Nevertheless, it is necessary to evaluate the possible detrimental effects of some treatments like gamma irradiation or essential oils on qualitative fruit parameters in view of their commercial application. In addition, the use of low doses of fungicides cannot be applied to organic production. Directions for further research: Specific appropriate strategies have to be evaluated for each species and pathogen in order to tailor a complete integrated disease management. Moreover, these integrated applications have to be investigated at commercial levels, including during fruit handling, in order to ascertain their practical efficacy.

Improvment Biocontrol of Damping-Off and Root Rot/Wilt of Faba Bean by Salicylic Acid and Hydrogen Peroxide

Rhizoctonia solani, Fusarium solani, F. oxysporum and Macrophomina phaseolina were found to be associated with root rot and wilt symptoms of faba bean plants collected from different fields in New Valley governorate, Egypt. All the obtained isolates were able to attack faba bean plants (cv. Giza 40) causing damping-off and root rot/wilt diseases. R. solani isolates 2 and 5, F. solani isolate 8, F. oxysporum isolate 12 and M. phaseolina isolate 14 were the more virulent ones in the pathogenicity tests. Biocontrol agents (Trichoderma viride, Bacillus megaterium) and chemical inducers (salicylic acid and hydrogen peroxide) individually or in combination were examined for biological control of damping-off and root rot/wilt and growth promotion of faba bean plants in vitro and in vivo. Both antagonistic biocontrol agents and chemical inducers either individually or in combination inhibited growth of the tested pathogenic fungi.Biocontrol agents combined with chemical inducers recorded the highest inhibited growth especially in case SA + T. viride and SA+ B. megaterium. Under green house and field conditions, all treatments significantly reduced damping-off and root rot/ wilt severity and increased survival of plants. Also, these treatments increased fresh and dry weights of the survived plants in pots compared with control. The combination of biocontrol agents and chemical inducers were more effective than using them individually and SA+ T. viride was the best treatment in this respect. Under field conditions, all these treatments significantly increased growth parameters (plant height and No. of branches plant-1) and yield components (No. of pods and seedsplant-1, weight of 100 seeds and total yield feddan-1 and protein content in both seasons (2010-2011 and 2011-2012). Faba bean seeds soaked in SA+ T. viride and SA+ B. megaterium were recorded the highest growth parameters and yield components. Generally, the combination of biocontrol agents and chemical inducers recoded the best results for controlling damping-off and root rot/wilt diseases in greenhouse and field with addition improved plant growth and increased yield components in the field.

Combinatorial effect of endophytic and plant growth promoting rhizobacteria against wilt disease of Capsicum annum L. caused by Fusarium solani

Combination of biocontrol agents that are compatible with each other is a strategic approach to control the plant disease and pest. The present study was designed to evaluate the protective effects of compatible endophytic bacterial strains ( Bacillus subtilis; EPCO16 and EPC5) and rhizobacterial strain ( Pseudomonas fluorescens; Pf1) against chilli wilt disease caused by Fusarium solani. Our results showed that B. subtilis (EPCO16 and EPC5) and P. fluorescens (Pf1) were compatible and effectively inhibited the growth of the F. solani. The application of endophytic and rhizobacterial strains, singly and in combination in green house and field conditions were found to be effective in controlling the chilli Fusarium wilt disease by inducing systemic resistance (ISR) as evidenced by enhanced activities of PO, PPO, PAL, β-1,3-glucanase, Chitinase and Phenolic involved in the synthesis of phytolaexins thereby promoting the growth of plants. However, combinations of EPCO16 + EPC5 + Pf1 bacterial strains were more effective than single agents. These findings suggest that synergistic interactions of biocontrol agents may be responsible for the management of chilli wilt disease caused by F. solani.

Integrated control of blue mould using new fungicides and biocontrol yeasts lowers levels of fungicide residues and patulin contamination in apples

We tested the compatibility of the biocontrol yeasts (Rhodosporidium kratochvilovae LS11 and Cryptococcus laurentii LS28) with the recently developed fungicides boscalid (BOSC), cyprodinil (CYPR) and fenhexamid (FENH) to create an efficient integrated approach to control blue mould on apples. The fungicide thiabendazole (TBZ), which is presently allowed for postharvest treatment of pome fruit in different countries, was also used as the control. Both the biocontrol agents (BCAs) LS11 and LS28 were compatible in vitro with BOSC and CYPR, whereas they were strongly inhibited by FENH. TBZ was compatible with LS28, while it strongly inhibited LS11. In vitro assays with some isolates of Penicillium expansum showed that the majority were resistant to TBZ, whereas they were all markedly inhibited by BOSC and CYPR. Experiments of integrated control were performed on wounded apples kept at 21°C up to 7 days. After 4 days of storage, the combination of a low BCA concentration (5×106cfumL−1) with a low dose (25% of the label dose) of commercial formulates of BOSC or CYPR, resulted in an efficient reduction of blue mould incidence (83–100% less infection with respect to the control). Conversely, the combination of BCAs with TBZ was less effective (not more than 60% of rot reduction). When applied alone at low dosage, LS11, LS28, BOSC, CYPR and TBZ reduced Penicillium rot by 35%, 52%, 67%, 72% and 0%, respectively. After 7 days of storage, only the integrated treatment based on BCAs with BOSC or CYPR resulted in a significant rot reduction (as much as 98%). Treatments based on the utilization of the BCA LS28 or low dosage of CYPR alone were much less effective (10% and 28% rot reduction, respectively), whereas both BCAs integrated with TBZ were ineffective. Furthermore, integrated treatments (BCAs+BOSC or CYPR) resulted in lower fungicide residues and patulin (PAT) contamination in apples. Our data show that the integration of biocontrol yeasts with a low rate of the recently commercialized fungicides BOSC or CYPR could be an effective and safer strategy to control P. expansum and keep fungicide residues as well as PAT contamination in apples low.

Biocontrol agents applied individually and in combination for suppression of soilborne diseases of cucumber

The soilborne pathogens Rhizoctonia solani, Pythium ultimum, and Meloidogyne incognita can cause severe economic losses to field- and greenhouse-grown cucumber. A collection of bacterial isolates and isolates GL3 and GL21 of Trichoderma virens were screened for suppression of diseases caused by these pathogens. T. virens isolates GL3 and GL21 provided the most effective suppression of damping-off caused by R. solani in greenhouse bioassays. Burkholderia ambifaria BC-F, B. cepacia BC-1, and Serratia marcescens N1-14 also provided significant suppression of R. solani relative to the pathogen check in some experiments. T. virens isolates GL3 and GL21 and S. marcescens isolates N1-6, N1-14, and N2-4 provided the most consistent and effective suppression of damping-off of cucumber caused by P. ultimum in growth chamber experiments. No microbial treatment containing individual or combined microbes significantly suppressed populations of M. incognita on cucumber or improved plant vigor in greenhouse bioassays. T. virens GL21 applied as a granular formulation, in combination with B. cepacia BC-1 or B. ambifaria BC-F applied as a seed treatment, significantly improved suppression of damping-off caused by R. solani over individual applications of these microbes in at least one experiment. Treatments combining B. cepacia BC-1, B. ambifaria BC-F, or S. marcescens isolates N1-14 or N2-4 with T. virens GL21 in R. solani biocontrol assays always resulted in plant stands that were similar or greater than treatments containing individual applications of these microbes. B. ambifaria BC-F combined with T. virens GL21 in seed treatments resulted in significantly improved suppression of damping-off caused by P. ultimum in two of three experiments. Populations of T. virens GL3 and GL21 were both substantially reduced after coincubation with B. cepacia BC-1, or S. marcescens isolates N1-14 or N2-4 for 10 to 12 d in cucumber rhizospheres. Populations of T. virens GL21 were slightly reduced after coincubation with B. ambifaria BC-F. Results presented here substantiate other studies reporting enhanced biocontrol performance with certain combinations of biocontrol agents. These results also indicate that antagonism among combinations of biocontrol agents can vary with the assay system employed.

Biological Control of Common Bunt (Tilletia tritici)

Summary Common bunt (Tilletia tritici syn. T. caries) is a significant seed-borne plant disease in organic agriculture. General measures in ecological crop protection like crop rotation and manuring have in practice failed to control this disease, and direct seed treatment may be necessary to ensure yield and food quality. The present study indicates that biological control can be successfully used without negative effects on seed germination and vigor. A combination of biocontrol agents and milk powder improves the efficacy of biocontrol. Application of compost to the soil increases the frequency of this disease. The potential role of biocontrol within the principles of ecological disease management is discussed.

Combining fluorescent Pseudomonas spp. strains to enhance suppression of fusarium wilt of radish

Fusarium wilt diseases, caused by the fungus Fusarium oxysporum, lead to significant yield losses of crops. One strategy to control fusarium wilt is the use of antagonistic, root-colonizing Pseudomonas spp. It has been demonstrated that different strains of these bacteria suppress disease by different mechanisms. Therefore, application of a mixture of these biocontrol strains, and thus of several suppressive mechanisms, may represent a viable control strategy. A prerequisite for biocontrol by combinations of biocontrol agents can be the compatibility of the co-inoculated micro-organisms. Hence, compatibility between several Pseudomonas spp. strains, that have the ability to suppress fusarium wilt of radish, was tested in vitro on KB agar plates. Growth of P. fluorescens strain RS111 was strongly inhibited by Pseudomonas spp. strains RE8, RS13, RS56 and RS158, whereas a mutant of strain RS111 (RS111-a) was insensitive to inhibition by these strains. Strains RS111 and RS111-a only slightly inhibited some other strains. Suppression of fusarium wilt of radish in a potting soil bioassay by the incompatible combination of RE8 and RS111 was comparable to the effects of the single strains. However, disease suppression by the compatible combination of RE8 and RS111-a was significantly better as compared to the single strains. In contrast, the incompatible combination of RS56 with RS111 resulted in enhanced disease suppression as compared to the single strains. Increased disease suppression by combinations of RS13 or RS158 with RS111 or RS111-a was not observed. This indicates that specific interactions between biocontrol strains influence disease suppression by combinations of these strains.