Influence of soil impoverishment on the interaction between Glomus mosseae and saprobe fungi

 The effect of the saprobe fungi Wardomyces inflatus (Marchal) Hennebert, Paecilomyces farinosus (Holm & Gray) A. H. S. Brown & G. Sm., Gliocladium roseum Bain., Trichoderma pseudokoningii Rifai and T. harzianum Rifai, isolated from sporocarps of Glomus mosseae, on arbuscular mycorrhizal (AM) colonisation and plant dry matter of soybean was studied in 2/3 and 1/5 diluted soils in a greenhouse trial. Soil dilution to 1/5 had no effect on shoot dry matter of soybean but decreased AM colonisation and root dry weight of plants. CFU of saprobe fungi, except T. harzianum, were higher in 1/5 than in 2/3 diluted soils. W. inflatus and Gliocladium roseum decreased the shoot dry weight of soybean plant when inoculated together with Glomus mosseae. The saprobe fungi P. farinosus and T. pseudokoningii increased the shoot dry weights of plants grown in 1/5 diluted soil. The shoot dry weight and AM colonisation in 1/5 diluted soil were also increased when T. harzianum was inoculated together with Glomus mosseae. Thus, saprobe fungi increased AM colonisation of soybean plants by indigenous endophytes. The AM colonisation of plants at both soil dilutions was increased by Glomus mosseae. The highest level of AM colonisation was observed when P. farinosus and T. pseudokoningii were inoculated together Glomus mosseae. The dilution of soils influenced the interaction between inoculated microorganisms and their effect on plant growth. Accepted: 7 June 1999     

Control of chickpea wilt (Fusarium oxysporum f.sp. ciceris) using Trichoderma spp. in Ethiopia

Thirty-two Trichoderma isolates were collected from soils grown with chickpea in central highlands of Ethiopia. The eight isolates were identified by CAB-International as Trichoderma harzianum, T. koningii and T. pseudokoningii. In in vitro tests, all Trichoderma isolates showed significant (P < 0.05) differences in their colony growth and in inhibiting the colony growth of Fusarium oxysporum f.sp. ciceris, race 3. In potted experiment, four Trichoderma isolates were tested as seed treatment on three chickpea cultivars (JG-62 susceptible, Shasho moderately susceptible and JG-74 resistant) against F. oxysporum f.sp. ciceris, race 3. The result showed that T. harzianum and unidentified Trichoderma isolate T23 significantly reduced wilt severity and delayed disease onset. The degree of wilt severity and delay of disease onset varied with chickpea cultivars. Our study revealed that biological control agents such as Trichoderma can be a useful component of integrated chickpea Fusarium wilt management.     

Phytopathogenic Fusarium oxysporum Schlecht, as a Necrotrophic Mycoparasite

Fusarium oxysporum f. sp. dianthi, f. sp. lycopersici, f. sp. cepae, f. sp. niveum and one unidentified F. oxysporum isolate proved to be active necrotrophic mycoparasites. In dual cultures hyphae of Trichoderma hamatum, T. longibrachiatum, T. pseudokoningii, T. harzianum, Botrytis cinerea and Rhizoctonia solani were parasitized and destroyed by F. oxysporum. One isolate of Phytophthora sp. was not affected. Mutual parasitism between F. oxysporum and T. pseudokoningii and T. longibrachiatum has been observed, too. Details of parasitic hyphal interactions: hyphal coiling, penetration sites, resistance sheat formation, hyphal invasion and internal growing are described. The mycoparasitic feature as well as antimicrobial metabolic production of F. oxysporum is probably a common phenomenon to ensure this important plant pathogenic species to compete successfully against other soil-borne fungal pathogens and saprophytes.     

Biocontrol efficacy of Trichoderma spp. against sesame wilt caused by Fusarium oxysporum f. sp. sesami

Sesame (Sesamum indicum L.) is one of the most important oilseed crops in Egypt and worldwide. It is being infected with many pathogens, among these pathogens Fusarium oxysporum f.sp. sesami (Zap.) Cast is causing severe economic losses on sesame. In this study, antagonistic capability of 24 isolates of Trichoderma spp. was assessed in vitro against F. oxysporum f.sp. sesami. Two strains; T. harzianum (T9) and T. viride (T21) were revealed to have high antagonistic effect against F. oxysporum f.sp. sesami in vitro with inhibition percentage about 70 and 67%, respectively. These two isolates proved to have high ability to control Fusarium wilt disease under greenhouse conditions. The highest reduction in disease severity was achieved with T. viride followed by T. harzianum with reduction in disease severity about 77 and 74%, respectively. This study revealed that the time of application of bioagents is a decisive factor in determining the efficacy of Trichoderma isolates to control Fusarium wilt of sesame. It was revealed that the highest reduction in the disease severity was achieved when either Trichoderma viride or T. harzianum were applied 7 days before challenging with the F. oxysporum f.sp. sesami.     

Antagonistic activity and hyphal interactions of Trichoderma spp. against Fusarium proliferatum and F. oxysporum in vitro

Trichoderma is a well-known antagonist against soilborne plant pathogens. However, the species and even various isolates have different biocontrol potential. To evaluate the antagonistic activities of Trichoderma harzianum, T. harzianum strain T100 (T100), T. viride and T. haematum against Fusarium oxysporum and F. proliferatum, we used dual culture and productions of volatile and non-volatile metabolites in three different phases in vitro. An analysis of the data in dual culture tests represented T. viride, T. haematum and T100 as effective antagonists of Fusarium while T100 was the only fungus being able to lyse the confronting mycelia. Similar results were obtained in the volatile metabolites tests also. In contrast with the two previous tests, the non-volatile metabolites produced by T. harzianum inhibited Fusarium mycelial growth the most, and T100 acted moderately. It was also clearly showed that the antagonistic effect of Trichoderma spp. was more on F. proliferatum than on F. oxysporum. Finally, because Trichoderma spp. was most effective in the second phase, we recommend to use T100 against F. proliferatum at the initial stages of infection as its mycoparasitism on F. oxysporum was observed microscopically through forming apressoria structures without any coiling around the pathogen.     

Biological Control of Fusarium spp. in Cotton, Wheat and Muskmelon by Trichoderma harzianum

A new isolate of Trichoderma harzianum (T-35) was isolated from the rhizosphere of cotton plants from a field infested with Fusarium. Under glasshouse conditions, the antagonist was applied to soil growing in a bran/peat mixture (1:1, v/v) or as a conidial suspension or used as a seed coating. When T. harzianum was tested against Fusarium oxysporum f. sp. vasinfectum, F. oxysporum f. sp. melonis or F. roseum‘Culmorum”, a significant disease reduction, was obtained in cotton, melon and wheat, respectively. Biological control of Fusarium wilt of cotton was achieved when tested at two inoculum levels of the pathogen (2 × 10⁷ and 2 × 10⁸ microconidia/kg soil), decreasing the Fusarium spp. soil population. The long term effect of T. harzianum on Fusarium wilt of cotton was studied using successive plantings. The antagonist persisted in soil throughout three consecutive plantings, reducing the Fusarium, wilt incidence in each growth cycle. At the first planting the largest amount of preparation was found superior, whereas at the third planting, no significant difference could be observed between the four rates of Trichoderma preparation. T. harzianum (T-35) controlled Fusarium wilt in cotton and muskmelon when applied in both naturally or artificially infested alluvial vertisol and sandy-loam soils, respectively. Soil or seed treatments with the antagonist provided a similar disease control of F. roseum‘Culmorum’ and of F. oxysporum f. sp. melonis.     

Diversity in soil fungi from undisturbed and disturbed Celtis tala and Scutia buxifolia forests in the eastern Buenos Aires province (Argentina)

The rhizospheric soil microfungi from a native forest (undisturbed and disturbed) were studied using soil dilution plate and soil washing methods. Fungi were isolated using slightly acid and alkaline culture media. 54 taxa were isolated: 49 from undisturbed forest soil and 37 from disturbed forest soil. Acremonium sp., Aspergillus ustus, Coemansia pectinata, Doratomyces stemonitis, Fusarium solani, F. oxysporum, Gliocladium roseum, Humicola fusco-atra, Mortierella sp., Penicillium lilacinum, Trichoderma harzianum, and T. koningii, showed the highest frequency, in both, undisturbed and disturbed forests. In undisturbed soil forest the biodiversity index was 3.97 whereas in disturbed ones was 3.89.     

Studies on the population dynamics and integrated management of Fusarium oxysporum f. sp. psidi (Fop), a cause of guava (Psidium guajava) wilt

To assess the impact of non-host crops intercropping, bioagents and oil cakes, on population dynamics of Fusarium oxysporum f. sp. psidii (Fop) and wilt of guava. Lowest population of Fop was recorded in garlic followed by intercropping with marigold with reduction of 84.9 and 83.9%, respectively. Bioagents viz; Aspergillus niger, Trichoderma viride and Trichoderma harzianum reduced the Fop population significantly, with the lowest in T. harzianum followed by A. niger. Garlic bulb extract exhibited maximum inhibition of Fop growth (2.7 cm) followed by marigold (2.4 cm), respectively, over control. Neem cake significantly reduced population of Fop, closely followed by mahua cake, over control. Integration of neem cake + T. harzianum + garlic reduced the Fop population significantly, over control, followed by neem cake + T. harzianum + marigold but neem cake + T. harzianum + marigold reduced wilt disease significantly in comparison to neem cake + T. harzianum + garlic inter-cropping.     

Spatial Peculiarities in the Colonization of the Plant Rhizoplane by Microscopic Fungi

Spatial peculiarities in the colonization of the tomato, cucumber, and barley rhizoplanes by microscopic fungi were studied. The apical zone of roots was colonized with a limited number of Rstrategists (the order Mucorales, Fusariumsp., Aspergillus niger, and Mycelia sterilia). The fungal population of the root hairs and the basal zone of roots was 2- to 3-fold denser due to the prevalence of Kstrategists. Fusaria, Fusarium oxysporumin particular, colonized roots in earlier terms than the genera Trichoderma, Penicillium, Gliocladium, and others. The F. oxysporumpopulation was at a maximum in the rhizoplane zone nearest the root tip.     

Antagonistic actions of Pythium oligandrum and Trichoderma harzianum against phytopathogenic fungi (Fusarium oxysporum and Pythium ultimum var. ultimum)

Abstract

The possible biological control of damping-off fungi, Fusarium oxysporum and Pythium ultimum by Pythium oligandrum or Trichoderma harzianum was in vitro investigated. Results of comparing the antagonistic activity of P. oligandrum and T. harzianum in dual plates against the tested phytopathogens indicated different degrees of antagonism. After 12 days of incubation colony of the phytopathogenic fungus was completely overgrown by the antagonist, except for the interaction between T. harzianum and F. oxysporum which showed no overgrowth or any hyphal penetration by the antagonist. However, growth and proliferation of F. oxysporum colony was repressed. T. harzianum and P. oligandrum produced chitinase and β-1,3-glucanase when they were grown on liquid culture medium supplemented with chitin or fungal dried mycelium as a sole carbon source, and enzyme production was higher by T. harzianum comparing with P. oligandrum under the same condition. Fungal dried mycelium of F. oxysporum was the most selective carbon source for enzyme production, on the other hand, chitinase production was significant locked when P. ultimum dried mycelium was used as a carbon source. Production of volatile compounds by P. oligandrum or T. harzianum against F. oxysporum and P. ultimum was examined using the inverted plates method. F. oxysporum was inhibited by the antagonist volatile compounds and it is inhibited 100% by increasing the amount of inoculum size. Production of potential biocontrol agents provided with economically features and working under field conditions are recommended.     

POPULATION DIFFERENCES IN INDIGENOUS FUSARIUM SPECIES BY CORN CULTURE OF PRAIRIE SOIL

Six species of Fusarium were identified among approximately 7,000 cultures isolated from roots and soils collected from prairies and cornfields in southern Minnesota. In both soil sources, F. oxysporum and F. solani predominated, followed in order by F. roseum, F. episphaeria, F. tricinctum, and F. moniliforme. The same order was obtained for the 28 species of prairie grasses and forbs as for corn. From prairie plant and corn roots, respectively, F. oxysporum was isolated from 64 and 90%; F. solani, 26 and 80%; F. roseum, 8 and 35%; and F. tricinctum, 6 % each. In 10 of 17 companion soil pairs, populations of Fusarium species were higher in cornfield than in prairie soils. Populations of F. roseum and F. moniliforme especially, were higher in cornfield soils of sample pairs, but populations of F. solani were higher in prairie soils. Fusarium roseum ‘Equiseti’ was the predominant cultivar of this species in both prairie and cornfield soils. Thus all six species of Fusarium appeared to be indigenous to the prairie, and some, especially F. roseum, apparently had increased in prevalence in soil and roots by corn culture.     

Efficacy of Bacillus subtilis and Trichoderma harzianum combination on chickpea Fusarium wilt caused by F. oxysporum f. sp. ciceris

Fusarium wilt is caused by F. oxysporum Schlecht end. Fr. f. sp. ciceris (FOC) is a devastating disease of chickpea in Algeria. In this study, antagonistic effects of B. subtilis MF352017 (Bs1) and Trichoderma harzianum KX523899 (T5) isolated from the rhizosphere of chickpea were investigated separately and in combination for their efficacy in controlling the disease in vivo. The efficacy of the antagonistic biocontrol agents on Fusarium wilt was evaluated based on vegetative and root growth parameters of chickpea. Seed bacterisation with B. subtilis MF352017 (Bs1) and seed treatment with T. harzianum (T5) significantly protected chickpea seedlings from FOC as compared to untreated plants. Plant protection was more pronounced in T. harzianum-treated plants than in bacterised plants. The application of both antagonists effectively suppressed 93.67% of the disease and also enhanced plant growth leading to increased plant height, root length, fresh and dry weights of shoot and root. The mixture of antagonists increased the effectiveness of B. subtilis MF352017 (Bs1) isolate on Fusarium wilt and improved chickpea growth.     

Effect of combination of bio-agents and mineral nutrients for the management of alfalfa wilt pathogen Fusarium oxysporum f. sp. medicaginis

Abstract

Biological and nutrient management of soil borne disease is increasingly gaining stature as a possible practical and safe approach. Inhibitory effects of fungal and bacterial antagonists were tested under in vitro conditions against the wilt pathogen of alfalfa Fusarium oxysporum f. sp. medicaginis. Trichoderma harzianum and Pseudomonas fluorescens (PI 5) were found to be effective against the alfalfa wilt pathogen. Manganese sulphate at 500 and 750 ppm inhibited the mycelial growth of F. oxysporumf. sp. medicaginis under in vitro conditions. In pot culture studies, manganese sulphate at 12.5 mg/kg reduced the wilt incidence (23.33%). Combined application of manganese sulphate 12.5 mg/kg + T. harzianum 1.25 mg/kg of soil significantly reduced the wilt incidence accompanied by improved plant growth and yield in pot culture. The mixture of manganese sulphate (25 kg/ha) + T. harzianum (2.5 kg/ha) significantly reduced the wilt incidence when applied as a basal dose in the field conditions. The average mean of disease reduction was 62.42% over control.     

Biological control of anthracnose of chilli with rhizosphere and rhizoplane fungal isolates from grasses

The fungal species from rhizosphere and rhizoplane of perennial grasses of the Western Ghats of India were studied for their pathogenicity, antagonism in vitro, substrate and root colonization abilities, rhizosphere competence, growth in different soil pH and inoculum shelf-life. Out of 138 non-pathogenic fungal isolates tested, 85 were antagonistic in vitro to chilli anthracnose pathogen Colletotrichum capsici. Fifteen isolates with >60% inhibition zone to pathogen culture had saprophytic and root and rhizosphere colonization abilities. The sorghum grain inocula of test antagonistic fungi- Fusarium oxysporum, Chaetomium globosum and Trichoderma harzianum had the shelf-life of 90 days at 20?±?2?°C and required optimum soil pH of 6.5. The above fungal isolates when tested for biocontrol of anthracnose disease in greenhouse and field caused reduction in seedling mortality and decreased disease incidence and severity at various plant growth stages and significant reduction in chilli fruit and seed infection. The test antagonistic fungi promoted seedling and mature plant growth and increased fruit and seed yield. Populations of these antagonistic fungi were fairly high in chilli rhizosphere at harvest. The present study indicated that antagonistic fungi from grass rhizosphere and rhizoplane could be used to control anthracnose and promote plant growth, and increase yield of chilli in field.     

Interaction between pathogenic and saprobic fungi isolated from soybean roots and seeds

A variety of interactions was recorded in culture between 11 saprobic fungi isolated from soybean (Glycine max) roots and seeds and the soybean pathogens Cercospora sojina, Colletotrichum truncatum, Macrophomina phaseolina, Phomopsis sojae, and Septoria glycines. The most active saprobes were Aspergillus terreus, Chaetomium cupreum, Epicoccum nigrum, Gliocladium roseum, Myrothecium roridum, Penicillium thomii, and Trichothecium roseum. Hyphal lysis of several fungal pathogens by Acremonium sp., C. cupreum and P. thomii was recorded perhaps because of parasitism by G. roseum and T. roseum. In greenhouse studies, seeds coated with G. roseum, P. thomii, and T. harzianum emerged significantly (P=0.05) more than those coated with A. terreus and the control. In field studies, seeds coated with a conidial suspension of A. terreus, G. roseum, P. thomii or Trichoderma harzianum produced a significantly greater stand than the control. The area of cotyledons covered with lesions caused by C. truncatum was significantly less on seeds coated with G. roseum, P. thomii and T. harzianum than the control.     

Trichoderma species on Agaricus bisporus farms in Serbia and their biocontrol

Twenty Trichoderma isolates were collected on 13 Serbian Agaricus bisporus farms and one in Bosnia and Herzegovina during 2006–2010. Twelve isolates were classified into five species by standard mycological studies and ITS1/ITS4 sequence analyses, namely Trichoderma atroviride, Trichoderma koningii, Trichoderma virens, Trichoderma aggressivum f. europaeum and Trichoderma harzianum. Eight isolates were not identified to the species level but were shown to be related to T. harzianum. The isolates of T. harzianum exhibited the highest virulence to the harvested A. bisporus pilei and T. virens and T. aggressivum f. europaeum the lowest. Antifungal activity of two biofungicides based on Bacillus subtilis and tea tree oil and the fungicide prochloraz manganese were tested in vitro to all Trichoderma isolates. Prochloraz manganese and B. subtilis were highly toxic to all tested Trichoderma isolates, their ED₅₀ values were below 0.3 and 1.3 mg L^?1, respectively. Tea tree oil did not exhibit a significant antifungal activity (ED₅₀ = 11.9–370.8 mg L^?1). The effectiveness of biofungicides was evaluated against T. harzianum in a mushroom growing room, and they were applied alone or in combination with the fungicide at a respective proportion of 20:80%. Prochloraz manganese showed higher effectiveness than both tested biofungicides or their respective mixtures. The biofungicide based on B. subtilis demonstrated greater effectiveness in preventing disease symptoms than tea tree oil. B. subtilis combined with the fungicide revealed less antagonism in effectiveness against pathogen than tea tree oil.     

Enzymes Associated with Defence against Toxic Oxygen Species in PCNB-Tolerant and Sensitive Soil Fungi

The specific activities of enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPOX) and glutathione reductase (GR), which are involved in protection against toxic species of oxygen, were determined in mycelia extracts of pentachloronitrobenzene (PCNB)-tolerant and susceptible soil fungi. The organisms assayed were the highly PCNB-sensitive Rhizoctonia solani and Rhizopus arrhizus; Sclerotium rolfsii and Trichoderma harzianum, which are moderately susceptible to PCNB, and the fungicide-tolerant Fusarium oxysporum f. sp. melonis and Pythium aphanidermatum. No GPOX activity was detected in the six examined fungi. Significant differences in the specific activities of the other enzyme systems among the fungi were evident. Remarkably low levels of CAT activities were measured in R. solani. Except for T. harzianum, no meaningful differences regarding SOD, CAT and GR activities with age of the fungi cultures were observed. The electrophoretic patterns of SOD and CAT displayed dissimilarities among the fungi under study. P. aphanidermatum is more polymorphic with respect to both SOD and CAT enzyme systems as compared to the other fungi. The SOD of F. oxysporum f. sp. melonis, R. arrhizus and T. harzianum is a cuprozinc enzyme, while the mangano-SOD species was detected in S. rolfsii, R. solani and T. harzianum.     

Antagonism between Gliodadium roseum,Trichoderma harzianum,or Trichothecium roseum and Phytophthora megasperma f. sp. glydnea

The antagonism between Gliodadium roseum, Trichoderma harzianum, or Trichothecium roseum and Phytophthora megasperam f. sp. glycinea (Pmg), cause of Phytophthora rot of soybeans (Glycine max), was studied. G. roseum, T. harzianum, and 17 isolates of T. roseum were grown separately on modified Czapek-Dox medium (MCD) in the dark for 25 days at 25 °C. Culture filtrates of T. roseum at 0.5% and 20.0% concentrations inhibited mycelial growth of Pmg at 3.1% and 90.4%; and those of G. roseum at –0.7% and 44.0%; and of T. harzianum at 0.7% and 46.0%, respectively. Culture filtrates of T. roseum at 0.5% concentration inhibited zoosporangenesis of Pmg at 98.0% and at 1.0% concentration prevented it. Culture filtrates of G. roseum and T. harzianum at 5% concentration significantly (P=0.05) inhibited zoosporangenesis of Pmg, but differences were not significant from that on MCD. Culture filtrates of 17 isolates of T. roseum inhibited mycelial growth and zoosporangenesis of Pmg at different percentages with different concentrations with those of isolate 9 showing the greatest inhibition of both. Mycelial growth of most of 16 races of Pmg was prevented at 10% concentration of the culture filtrates of isolate SS-2 of T. roseum, and all 16 races, except race 6, was prevented at 20% concentration. Zoosporangenesis of all races of Pmg was prevented at 2% the culture filtrate of SS-2. Culture filtrates of SS-2 inhibited zoosporangenesis of Pmg in soil.     

Mycoparasitism of Trichoderma spp. in biocontrol of fusarial wilt of tomato

Wilt of tomato caused by Fusarium oxysporum is one of the most serious diseases posing a threat to its cultivation. As such a thorough search was made to evaluate the mycoparasitic potentiality of three species of Trichoderma, T. harzianum, T. viride and T. hamatum towards minimising the effect of the pathogen on ravages of the crop. All the experimental species of Trichoderma were able to produce lytic enzymes, β-1,3 glucanase and chitinase efficiently but their activity could be hastened up in the presence of cell wall material of the pathogen where T. harzianum was recorded to be the best in rank. Lysis of mycelium of the pathogen was achieved by treatment with metabolic filtrate of the antagonistic fungi. SEM micrographs correspondingly showed lysis of pathogenic mycelium due to overgrowth and penetration through hyphal pegs and coiling produced by T. harzianum. Application of the antagonistic fungi in the field showed their ability to reduce the incidence of the wilt disease to a reasonable extent where the performance of T. harzianum happened to be superior over the others.     

Biological control of Fusarium oxysporum f. sp. radicis-cucumerinum by some Trichoderma harzianum isolates

The purpose of this study was to investigate the effects of isolates T₂₂, T₉ and T₆ of Trichoderma harzianum on isolate F₄₂ of Fusarium oxysporum f. sp. radicis-cucumerinum. The effect of T. harzianum isolates on controlling disease was examined under greenhouse conditions. Results showed that these three isolates, respectively, had the high effect on inhibition of pathogen growth. In examining the severity of disease in the greenhouse, it was found that isolate T₂₂ had the greatest effect on controlling the pathogen. The results of volatile compounds showed that these isolates, respectively, were effective in reducing mycelial growth of isolate F₄₂. The highest peroxidase activity was observed on the fourth day in isolate T₆ and the highest phenylalanine ammonia lyase enzyme activity was observed on the fifth day in isolate T₂₂. Based on the results, isolate of T₂₂ showed the greatest effect on the induction of resistance against F₄₂ and may be a successful agent for biological control of root and stem rot of cucumber.