Biocontrol Fungus Trichoderma Harzianum Research Articles

Spherical Fe2O3 nanoparticles inhibit the production of aflatoxins (B1 and B2) and regulate total soluble solids and titratable acidity of peach fruit

Aflatoxin is a group I carcinogen and causes significant public health and food safety risks, throughout the world. This study was carried out to assess the levels of aflatoxin contamination in diseased peach (Prunus persica L.) fruit and their control using myco-synthesized iron oxide nanoparticles (Fe2O3 NPs). Diseased peach fruit were diagnosed to be infected with Aspergillus flavus. The isolated pathogen was cultured under UV light (365 nm) and exposed to ammonium hydroxide (31 %) vapors, which confirmed its ability to produce aflatoxin. For the control of this disease, Fe2O3 NPs were synthesized in the filtrate of a biocontrol fungus (Trichoderma harzianum) and characterized before analyzing their potential in disease control. FTIR spectrum described the presence of capping and reducing agents (secondary amines, alcohol, alkyne and aromatic compounds) on the surface of Fe2O3 NPs. X-ray Diffraction (XRD) described the crystalline size (7.78), while the spherical shape of Fe2O3 NPs was described by the SEM analysis. The EDX spectrum indicated the successful formation of Fe2O3 NPs by showing strong signals of iron (74.38 %). All concentrations displayed mycelial growth inhibition, in vitro and the greatest growth reduction (65.4 %) was observed at 1 mg/ml concentration of NPs. At the same concentration of Fe2O3 NPs, significant control of fruit rot of peach was also observed, in vivo. Treatment of Fe2O3 NPs maintained higher soluble solids, sucrose, total sugar, ascorbic acid, titratable acidity and firmness of peach fruit. Diseased fruit were further investigated for the presence and detection of aflatoxins. All three methods viz. thin layer chromatography (TLC), enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC) confirmed a higher production of aflatoxins in control plants, while this production was significantly reduced in Fe2O3 NPs-treated peach fruit.

The Use of Some Animal Wastes in the Control of the Pathogenic Fungi Fusarium Solani And Rhizoctonia Solani on Tomato Plants

Background: This study was conducted to evaluate the efficiency of animal waste in controlling seedling death and root rot diseases in tomato caused by the pathogenic fungi Fusarium solani and Rhizoctonia solani In open field conditions, which were isolated from the soil of different locations. singly or in combination with the bio-control fungus Trichoderma harzianum.
 Materials and Methods: The fungal pathogens and fungi, Fusarium solani and Rhizoctonia solani, were tested and diagnosed, and the pathogenicity of the fungal isolates was tested. The resistance preparation was introduced, and the terrain ability was tested for it
 Results:The results of the pathogenicity test showed that the isolates taken from the greenhouses / Hilla R. solani and F. solani had the highest percentage of seedling mortality after emergence, reaching 97.500 and 95.00, respectively.The interaction showed the antagonistic ability of the fungus Trichoderma harzianum against the pathogenic fungi R. solani and F. solani, achieving an antibody score of 2.25
 Conclusion: The results of the aqueous extract of animal waste showed a significant reduction of the two pathogens R.solani and F.solani, where it reached the highest value at 4.100 when isolate F.solani for poultry extract and the smallest value was 8.300 when extracting cows, while all aqueous extracts did not affect the growth of the biofungus T. harzianum .It amounted to 8,900, 9,000, 8,925, and 8,925 (cows, sheep, horses, and poultry), respectively. The results of the laboratory isolation of animal waste showed the presence of (6) species of fungi.. Alternaria sp, Aspergillus niger, Penicillium sp, Trichoderma harzianum , macrohpomina sp , Cylindrocarpon sp

Structures and Biological Activities of Secondary Metabolites from Trichoderma harzianum.

The biocontrol fungus Trichoderma harzianum, from both marine and terrestrial environments, has attracted considerable attention. T. harzianum has a tremendous potential to produce a variety of bioactive secondary metabolites (SMs), which are an important source of new herbicides and antibiotics. This review prioritizes the SMs of T. harzianum from 1988 to June 2022, and their relevant biological activities. Marine-derived SMs, especially terpenoids, polyketides, and macrolides compounds, occupy a significant proportion of natural products from T. harzianum, deserving more of our attention.

Elucidating the microbiome of the sustainable peat replacers composts and nature management residues.

Sustainable peat alternatives, such as composts and management residues, are considered to have beneficial microbiological characteristics compared to peat-based substrates. Studies comparing microbiological characteristics of these three types of biomass are, however, lacking. This study examined if and how microbiological characteristics of subtypes of composts and management residues differ from peat-based substrates, and how feedstock and (bio)chemical characteristics drive these characteristics. In addition, microbiome characteristics were evaluated that may contribute to plant growth and health. These characteristics include: genera associated with known beneficial or harmful microorganisms, microbial diversity, functional diversity/activity, microbial biomass, fungal to bacterial ratio and inoculation efficiency with the biocontrol fungus Trichoderma harzianum. Bacterial and fungal communities were studied using 16S rRNA and ITS2 gene metabarcoding, community-level physiological profiling (Biolog EcoPlates) and PLFA analysis. Inoculation with T. harzianum was assessed using qPCR. Samples of feedstock-based subtypes of composts and peat-based substrates showed similar microbial community compositions, while subtypes based on management residues were more variable in their microbial community composition. For management residues, a classification based on pH and hemicellulose content may be relevant for bacterial and fungal communities, respectively. Green composts, vegetable, fruit and garden composts and woody composts show the most potential to enhance plant growth or to suppress pathogens for non-acidophilic plants, while grass clippings, chopped heath and woody fractions of compost show the most potential for blends for calcifuge plants. Fungal biomass was a suitable predictor for inoculation efficiency of composts and management residues.

ThpacC Acts as a Positive Regulator of Homodimericin A Biosynthesis and Antifungal Activities of Trichoderma harzianum 3.9236.

The Pal/Rim pathway and its key transcription factor PacC play important roles in fungal adaptation to ambient pH regarding growth, secondary metabolism, and virulence. However, the effect of PacC on the secondary metabolism of the important biocontrol fungus Trichoderma harzianum remains elusive. To answer this question, ThpacC deletion (KO-ThpacC) and overexpression (OE-ThpacC) mutants of T. harzianum 3.9236 were constructed. Transcriptomic analysis of T. harzianum and KO-ThpacC suggested that ThpacC acted as both a positive and a negative regulator for secondary metabolite (SM) production. Further investigation revealed that deletion of ThpacC abolished homodimericin A and 8-epi-homodimericin A production. Moreover, ThpacC plays a role in the antagonism of T. harzianum against Sclerotinia sclerotiorum. 8-epi-Homodimericin A demonstrated moderate inhibitory activity against S. sclerotiorum. Our results contribute to a deeper understanding of the ThpacC function on SM production and the antifungal activity of T. harzianum.

Indigenous Fungivorous Nematodes Affect the Biocontrol Efficacy of Trichoderma harzianum through Reducing the Hyphal Density.

Indigenous fungus-feeding nematodes may adversely affect the growth and activity of introduced biocontrol fungi. Alginate pellets of the biocontrol fungus Trichoderma harzianum ThzID1-M3 and sclerotia of the fungal plant pathogen Sclerotinia sclerotiorum were added to nonsterile soil at a soil water potential of -50 or -1,000 kPa. The biomass of ThzID1-M3, nematode populations, and extent of colonization of sclerotia by ThzID1-M3 were monitored over time. The presence of ThzID1-M3 increased the nematode population under both moisture regimes (p < 0.05), and fungivores comprised 69-75% of the nematode population. By day 5, the biomass of ThzID1-M3b and its colonization of sclerotia increased and were strongly correlated (R2 = 0.98), followed by a rapid reduction, under both regimes. At -50 kPa (the wetter of the two environments), fungal biomass and colonization by ThzID1-M3 were less, in the period from 5 to 20 days, while fungivores were more abundant. These results indicate that ThzID1-M3 stimulated the population growth of fungivorous nematodes, which in turn, reduced the biocontrol ability of the fungus to mycoparasitize sclerotia. However, colonization incidence reached 100% by day 5 and remained so for the experimental period under both regimes, although hyphal fragments disappeared by day 20. Our results suggest that indigenous fungivores are an important constraint for the biocontrol activity of introduced fungi, and sclerotia can provide spatial refuge for biocontrol fungi from the feeding activity of fungivorous nematodes.

Coinoculation of soybean plants with Bradyrhizobium japonicum and Trichoderma harzianum: Coexistence of both microbes and relief of nitrate inhibition of nodulation

Coinoculation of plants with mixtures of beneficial microbes sometimes produces synergistic effects. In this study, the effect of soybean coinoculation with the N2-fixing Bradyrhizobium japonicum E109 and the biocontrol fungus Trichoderma harzianum Th5cc was analyzed. Nodulation by E109 was not hampered by Th5cc, which antagonized five out of seven soybean pathogens tested. Furthermore, Th5cc relieved nitrate-inhibition of nodulation, enabling the formation of nodules containing infected cells with bacteroids in the presence of the otherwise inhibitory 10 mM KNO3. Th5cc released micromolar amounts of auxin, and addition of 11 μM indoleacetic acid to soybean plants inoculated with E109 in the absence of Th5cc also induced nodulation in the presence of 10 mM KNO3. Thus, Th5cc may release auxins into the soybean rhizosphere, which hormones might participate in overcoming the nitrate-inhibition of nodulation. Our results suggest that soybean plants coinoculated with these microorganisms might benefit from biocontrol while contributing to soil-nitrogen preservation.

Evaluation the potential of indigenous biocontrol agent Trichoderma harzianum and its interactive effect with nanosized ZnO particles against the sunflower damping-off pathogen, Rhizoctonia solani

Rhizoctonia solani is a phytopathogenic fungus affecting a wide range of plants hosts including the sunflower causing various diseases such as damping-off. Current management approaches of this pathogen are inadequate. Aim of this study was to assess the potential of eco-friendly control methods, the indigenous biocontrol fungus Trichoderma harzianum and ZnO nanoparticles for controlling of the sunflower damping-off pathogen, R. solani. The biocontrol agent T. harzianum showed a high antagonism effect on R. solani growth. Additionally, growth of R. solani was significantly (p = 0.01) reduced gradually by presence of various concentrations of the ZnO NPs indicating to concentration-dependent toxicity effect. However, a similar impact was also observed on growth of T. harzianum. On the other hand, the percentage of seed germination and stem length of sunflower (Coban cv.) did not affect significantly by ZnO NPs. Conversely, the root lengths were significantly decreased. In the horticultural canopy trial, the best reduction to the sunflower damping-off incidence percentage was achieved by treatment of sunflower seedlings growing in compost inoculated with T. harzianum and R. solani 68.75% comparing to 100% in the control. In contrast, a significant reduction in severity percentage of damping-off symptoms was accomplished in most of the treatments. The best suppression was achieved in treatments of spraying the seedlings with ZnO NPs (15 mg/ml) in two days prior of planting that was 50% in compression with 97.50% in control. These findings can justify the application of the local biocontrol agent T. harzianum alone or in integration with ZnO NPs to be included with current management approaches of sunflower damping-off, which could lead to a diminution in the utilizing of fungicides.

Differential Selection by Nematodes of an Introduced Biocontrol Fungus vs. Indigenous Fungi in Nonsterile Soil.

Trophic interactions of introduced biocontrol fungi with soil animals can be a key determinant in the fungal proliferation and activity. This study investigated the trophic interaction of an introduced biocontrol fungus with soil nematodes. The biocontrol fungus Trichoderma harzianum ThzID1-M3 and the fungivorous nematode Aphelenchoides sp. (10 per gram of soil) were added to nonsterile soil, and microbial populations were monitored for 40 days. Similar results were obtained when the experiment was duplicated. ThzID1-M3 stimulated the population growth of indigenous nematodes (p < 0.05), regardless of whether Aphelenchoides sp. was added. Without ThzID1-M3, indigenous nematodes did not increase in number and the added Aphelenchoides sp. nematodes almost disappeared by day 10. With ThzID1-M3, population growth of nematodes was rapid between 5 and 10 days after treatment. ThzID1-M3 biomass peaked on day 5, dropped at day 10, and then almost disappeared at day 20, which was not influenced by the addition of nematodes. In contrast, a large quantity of ThzID1-M3 hyphae were present in a heat-treated soil in which nematodes were eliminated. Total fungal biomass in all treatments peaked on day 5 and subsequently decreased. Addition of nematodes increased the total fungal biomass (p < 0.05), but ThzID1-M3 addition did not affect the fungal biomass. Hyphae of total fungi when homogenously distributed did not support the nematode population growth; however, hyphae of the introduced fungus did when densely localized. The results suggest that soil fungivorous nematodes are an important constraint on the hyphal proliferation of fungal agents introduced into natural soils.

Investigating Disease Controlling Ability of Brassica Volatiles and Their Compatibility with Trichoderma harzianum

The present investigation aimed to test the in vitro toxicity of Brassica volatiles against soil-borne plant pathogens (Rhizoctonia solani Kuhn, Sclerotium rolfsii Sacc., Fusarium oxysporum f.sp. ciceris (Padwick) Matuo & K. Sato and Sclerotinia sclerotiorum (Lib.) de Bary) and biocontrol fungus Trichoderma harzianum Rifai. Moreover, the response of T. harzianum to toxic volatiles was also studied in terms of glucanase and chitinase gene expression. A strong fungistatic effect of B. alba treatment was recorded against all the test pathogens. Noticeably, S. sclerotiorum manifested least sensitivity among all the tested pathogens. All T. harzianum isolates were less sensitive as compared to the assayed pathogens. Based on the in vitro study involving 6 T. harzianum isolates, T55 and Th-R showed least, while T39 showed highest sensitivity to the volatiles. Interestingly, the patterns relating to the effect of volatiles on inoculum density of T. harzianum isolates were similar to their effect on fungus growth in vitro. More importantly, expression of chitinase and glucanase genes in different Trichoderma isolates was up-regulated, which could improve the biocontrol activity of T. harzianum. Therefore, here the authors envisage that combining biocontrol and biofumigation has the potential to provide sustainable and cost-effective strategies to manage soil-borne plant pathogens.

De novo transcriptome analyses of host-fungal interactions in oil palm (Elaeis guineensis Jacq.).

BackgroundBasal stem rot (BSR) is a fungal disease in oil palm (Elaeis guineensis Jacq.) which is caused by hemibiotrophic white rot fungi belonging to the Ganoderma genus. Molecular responses of oil palm to these pathogens are not well known although this information is crucial to strategize effective measures to eradicate BSR. In order to elucidate the molecular interactions between oil palm and G. boninense and its biocontrol fungus Trichoderma harzianum, we compared the root transcriptomes of untreated oil palm seedlings with those inoculated with G. boninense and T. harzianum, respectively.ResultsDifferential gene expression analyses revealed that jasmonate (JA) and salicylate (SA) may act in an antagonistic manner in affecting the hormone biosynthesis, signaling, and downstream defense responses in G. boninense-treated oil palm roots. In addition, G. boninense may compete with the host to control disease symptom through the transcriptional regulation of ethylene (ET) biosynthesis, reactive oxygen species (ROS) production and scavenging. The strengthening of host cell walls and production of pathogenesis-related proteins as well as antifungal secondary metabolites in host plants, are among the important defense mechanisms deployed by oil palm against G. boninense. Meanwhile, endophytic T. harzianum was shown to improve the of nutrition status and nutrient transportation in host plants.ConclusionThe findings of this analysis have enhanced our understanding on the molecular interactions of G. boninense and oil palm, and also the biocontrol mechanisms involving T. harzianum, thus contributing to future formulations of better strategies for prevention and treatment of BSR.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2368-0) contains supplementary material, which is available to authorized users.

English

Successful integration of biocontrol organisms into agricultural production systems requires knowledge of their compatibility with commonly used pesticides. The compatibility of the biocontrol fungus Trichoderma harzianum (Eco-T &reg;) with a pesticide mix containing imidacloprid, metalaxyl and thiram (Product X) was assessed for maize seed treatment. Laboratory evaluations demonstrated that Product X caused up to 97.6% mortality of T. harzianum in a period as short as 3 days after seed treatment. Under greenhouse conditions, combined treatment of T. harzianum and Product X resulted in a significant reduction in percentage germination, dry shoot biomass and maize vigour when compared to single treatment with T. harzianum. Seed treatment with T. harzianum significantly enhanced maize germination, dry shoot biomass and vigour.&nbsp; In contrast, treating maize seed with Product X showed no actual benefit towards optimizing maize seedling growth. &nbsp; Key words: Biological control, compatibility, maize, pesticides, Trichoderma harzianum.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;

TRICHODERMA HARZIANUM T22 INDUCES IN MAIZE SYSTEMIC RESISTANCE AGAINST FUSARIUM VERTICILLIOIDES

SUMMARY Fusarium verticillioides is one of the most common plant pathogenic fungi affecting maize causing ear and kernel rot. Nearly the totality of the fungal strains are able to produce mycotoxins known as fumonisins at very different levels. However, information on the ability of the biocontrol fungus Trichoderma harzianum to induce systemic resistance in maize against F. verticillioides is still lacking. We now show that, upon root colonization by T. harzianum, F. verticillioides consistently reduces maize disease symptoms. The enhanced activation of SA- and JA/ ET-dependent defence responses indicates that resistance in maize is caused by a better perception of the fungal pathogen due to the effect of Trichoderma inocula. Seed biopriming with T. harzianum could be a useful strategy to control F. verticillioides infection and fumonisin accumulation under field conditions.

Antifungal Cyclic Lipopeptides from Bacillus amyloliquefaciens Strain BO5A

A bioassay-guided fractionation of Bacillus amyloliquefaciens strain BO5A afforded the isolation of two new cyclic lipopeptides (1 and 2) as the major lipid constituents (>60%) of the CHCl3-MeOH (2:1) extract. The chemical structures of the isolated metabolites were elucidated by spectroscopic methods, including 1D and 2D NMR spectroscopy, mass spectrometry (MS), secondary ion mass spectrometry (MS1, MS2), and chemical degradation. The compounds are members of the surfactins family and are based on a heptapeptide chain composed by Glu-Val-Leu-Val-Asp-Leu-Leu. Its N-terminal end is N-acylated by an (R)-3-hydroxy fatty acid with linear alkyl chains of 16:0 and 15:0 (1 and 2, respectively). The 3-hydroxyl group closes a 25-membered lactone ring with the carboxylic group of the C-terminal amino acid. The isolated compounds were tested for their inhibitory activity against the four pathogenic fungi Fusarium oxysporum, Aspergillus niger, Botrytis cinerea, and Penicillium italicum and the biocontrol fungus Trichoderma harzianum. Compound 2 displayed activity against all tested pathogens.

Relationship between the biocontrol fungus Trichoderma harzianum and the phytopathogenic fungus Fusarium solani f.sp. pisi

Relationship between the biocontrol fungus Trichoderma harzianum ThzID1-M3 and the plant pathogen Fusarium solani f.sp. pisi (Fsp) was determined in this study. Dual culture assay indicated the competitive interaction between ThzID1-M3 and Fsp. Alginate pellets of ThzID1-M3 and Fsp conidia were added to non-sterile soil with pea seeds. The interaction between Trichoderma and Fsp adversely affected their establishment in soil. The addition of ThzID1-M3 significantly reduced the Fsp population, as well as the colonization of roots by Fsp. In contrast, the added Fsp significantly reduced the proliferation of ThzID1-M3 and Trichoderma spp. The results suggest that the competition may be the main mechanism of the antagonistic activity of Trichoderma against Fsp.

Isolation and functional analysis of Thmfs1, the first major facilitator superfamily transporter from the biocontrol fungus Trichoderma harzianum

A novel major facilitator superfamily (MFS) transporter gene, Thmfs1, was isolated from Trichoderma harzianum (T. harzianum). A Thmfs1 over-expressing mutant displayed enhanced antifungal activity and fungicide tolerance, while the Thmfs1 disruption mutant showed the opposite trend. Trichodermin production in Thmfs1 disruption group (185 mg l(-1)) was decreased by less than 17 % compared to the parental strain, suggesting that Thmfs1 is not mainly responsible for trichodermin secretion. Real-time PCR showed that Thmfs1 transcript level could be induced by a certain range of trichodermin concentrations, while expression of Tri5, encoding a trichodiene synthase, was strongly inhibited under these conditions. To our knowledge, Thmfs1 is the first MFS transporter gene identified in T. harzianum.

Separation and Identification of Volatile Compounds from Liquid Cultures of Trichoderma harzianum by GC-MS using Three Different Capillary Columns

A simple, fast, repeatable and less laborious sample preparation protocol was developed and applied for the analysis of biocontrol fungus Trichoderma harzianum strain FA1132 by using gas chromatography-mass spectrometry. The match factors for sample spectra with respect to the mass spectra library of fungal volatile compounds were determined and used to study the complex hydrocarbons and other volatile compounds, which were separated by using different capillary columns with nonpolar, medium polar and high polar stationary phases. To date, more than 278 volatile compounds (with spectral match factor at least 90%) such as normal saturated hydrocarbons (C7-C30), cyclohexane, cyclopentane, fatty acids, alcohols, esters, sulfur-containing compounds, simple pyrane and benzene derivatives have been identified. Most of these compounds have not previously been reported. The method described in this paper is a more convenient research tool for the detection of volatile compounds from the cultures of T. harzianum.

Transcriptomic response of Arabidopsis thaliana after 24 h incubation with the biocontrol fungus Trichoderma harzianum

Trichoderma harzianum is a fungus used as biocontrol agent using its antagonistic abilities against phytopathogenic fungi, although it has also direct effects on plants, increasing or accelerating their growth and resistance to diseases and the tolerance to abiotic stresses. We analyzed Arabidopsis thaliana gene expression changes after 24h of incubation in the presence of T. harzianum T34 using the Affymetrix GeneChip Arabidopsis ATH1. Because this microarray contains more than 22,500 probe sets representing approximately 24,000 genes, we were able to construct a global picture of the molecular physiology of the plant at 24h of T. harzianum–Arabidopsis interaction. We identified several differentially expressed genes that are involved in plant responses to stress, regulation of transcription, signal transduction or plant metabolism. Our data support the hypothesis that salicylic acid- and jasmonic acid-related genes were down-regulated in A. thaliana after 24h of incubation in the presence of T. harzianum T34, while several genes related to abiotic stress responses were up-regulated. These systemic changes elicited by T. harzianum in Arabidopsis are discussed.

ROOT COLLAR EXCAVATION WITH TRICHODERMA INOCULATIONS AS A POTENTIAL MANAGEMENT STRATEGY FOR HONEY FUNGUS (ARMILLARIA MELLE A)

Summary Honey fungus (Armillaria mellea) is an important pathogen that can cause severe damage to infected trees and other plants. In this study we investigated the effect of air-spading and/or inoculation with a bio-control fungus as controls for honey fungus. Air-spading uses compressed air to de-compact soil while causing minimal disturbance or damage to the root system. Air-spading can also use compressed air to permanently remove soil from the base of the tree trunk to the depth at which main roots originate, a technique known as root collar excavation. The bio-control fungus Trichoderma harzianum strain (Trade name Trianum) is a root symbiont that is known to protect host plants from a range of pathogenic fungi. Raised beds were constructed and artificially inoculated with A. mellea while non-A. mellea infected beds acted as controls. One year later A. mellea infected raised beds were subjected to one of the following treatments i) no treatment ii) air-spading, iii) air-spading + T. harzianum or iv) T. harzianum only. The effectiveness and longevity of air-spading and T. harzianum was determined by potting up strawberry plants cv Cambridge favourite (highly susceptible to honey fungus attack) at month 6, 12, 18 and 24 after treatment. A. mellea infection was then quantified at day 90 after potting up by assessing visual plant condition, leaf chlorophyll fluorescence Fv/Fm, leaf chlorophyll content (SPAD) values and fruit yield per plant. Air-spading A. mellea infested soil with and without T. harzianum resulted in a two year protective period in which A. mellea failed to re-infect strawberry plants. In addition, failure to re-isolate A. mellea from media after air-spading indicates the air spading process may have eradicated A. mellea from the infected raised bed. Some degree of protective properties against A. mellea was confirmed when applying T. harzianum alone. For example, based on visual plant condition, application of T. harzianum reduced A. mellea severity by 12.5–65.7% over the two year study. Findings of this study strongly indicate that air-spading followed by inoculation with T. harzianum appears to offer promise as a joint cultural/bio-control strategy for the management of A. mellea. Results however, should be interpreted with some degree of caution as experiments were conducted under controlled conditions where soil conditions may vary from that in a woodland, forest or urban environment.

The in vitro effect of certain fungicides, insecticides, and biopesticides on mycelial growth in the biocontrol fungus Trichoderma harzianum

The in vitro effect of certain fungicides, insecticides, and biopesticides on mycelial growth of Trichoderma harzianum was evaluated. Seven systemic fungicides, 2 contact fungicides, and 4 biopesticides were tested. A progressive increase in percent inhibition of radial growth in the fungus was observed as the concentrations of the fungicides increased. Among the systemic fungicides, hexaconazole was the most toxic, followed by propiconazole and triflumizole. Toxicity of the contact fungicides was lower than that of the systemic fungicides, among which copper oxychloride and copper hydroxide were highly compatible; no inhibition was observed at lower concentrations. In terms of the insecticides tested, quinalphos and dicofol exhibited toxicity (quinalphos more so), even at the low concentration of 10 ppm. Endosulfan, fenpropathrin, and propargite were less toxic, which indicated the compatibility of these insecticides with T. harzianum. A varying level of inhibition was observed in response to the biopesticides. Although neem-based biopesticides completely inhibited the growth of the biocontrol strain, ovis was compatible with the growth of Trichoderma harzianum. The present results will help delineate the possibility of combining T. harzianum biocontrol agents and agrochemicals for use in an integrated pest management approach.