The infection of oranges by Trichoderma viride and mixed infection by Trichoderma viride and Penicillium digitatum

Trichoderma viride spores applied in water to apparently uninjured skin of oranges do not cause lesions. Adding orange juice, rind extract, citric acid or orange essential oil did not influence infection. Oranges became infected only when the stem-end cuts or wounds deeper than 6 mm into oil vesicles were inoculated. Sound oranges in contact with decayed oranges did not become infected. Diphenyl-impregnated wrappers reduced infection. A mixed inoculum of T. viride and Penicillium digitatum caused as fast rotting as P. digitatum, which caused faster rotting than T. viride alone. Lesions infected with P. digitatum could become infected by T. viride but those caused by T. viride did not become infected by P. digitatum. T. viride was antagonistic to P. digitatum in vivo and in vitro, possibly because it produces a heat-labile diffusible substance toxic to P. digitatum.     

Evaluation of Some Fungi and Bacteria for Potential Control of Safflower Rust

Some fungal and bacterial isolates applied as soil and seed treatments in greenhouse trials gave a good protection against Puccinia carthami Cda. on safflower, significantly reducing the infection from rust-infested seeds. Trichoderma viride and T. harzianum added alone and in combination as air-dried inoculum to the soil were the most effective fungal isolates. However T. viride at two higher rates reduced the rate of emergence of safflower seedlings. Among bacteria, Bacillus subtilis, B. cereus, isolates of Pseudomonas fluorescens and B. thuringiensis reduced rust infection when added both as soil drench and as seed treatment. Good results in the biocontrol of P. carthami were also obtained with some combination antagonist treatments such as T. viride + B. cereus, T. viride + P. fluorescens (16), T. viride + T. harzianum + B. cereus and T. viride +, T. harzianum + P. fluorescens (16). Fungal isolates added as soil treatment increased seedling length, whereas no similar effects were observed when these isolates were applied as seed treatment.     

In vitro and in vivo antagonism of biocontrol agents against Colletotrichum lindemuthianum causing bean anthracnose

Bean anthracnose caused by Colletotrichum lindemuthianum is a serious seed borne disease. For devising an effective management strategy, the efficacy of different bioagents, viz. Trichoderma viride, Trichoderma harzianum, Trichoderma hamatum and Gliocladium virens conducted under in vitro and in vivo conditions revealed maximum inhibition of mycelial growth in dual culture (59.48%) and inverted plate (55.98%) with T. viride. All the bioagents overgrew the pathogen and the principal mechanism of mycoparisitism observed was coiling, brusting and disintegration of pathogen hyphae. Culture filtrate from T. viride was found best as it completely inhibited radial growth at 25 and 50% concentration and reduced the spore germination of test fungus significantly. However, lower concentrations of culture filtrate from all bioagents showed little effect on spore germination. Seed application of bioagents was found better as compared to soil application. A maximum increase in seed germination and inhibition of seed borne infection was observed with T. viride followed by T. harzianum under pot culture conditions. T. viride has the maximum potentiality to suppress the spore germination, mycelial growth, seed borne infection of C. lindemuthianum and increased seed germination when compared with the other biocontrol agents.     

Changes in growth competence of aged <Emphasis Type="Italic">Trichoderma viride</Emphasis> vegetative mycelia

Identical masses of submerged Trichoderma viride mycelia of various ages were used as inoculum for a second submerged cultivation lasting for 24 h. It was found that the growth yield of secondary culture was dependent on the age of inoculum. The growth yields increased when the age of primary culture was less than 3 d, and decreased down to zero when older mycelia were inoculated. The mycelia were living even after 1 month of submerged cultivation, as they formed conidia after inoculating onto solid medium. In order to elucidate underlying biochemical processes, developmental changes of specific activities of organellar marker enzymes were measured in the mitochondrial/vacuolar and microsomal fractions of mycelia. These activities changed during the growth of mycelia in a biphasic manner and their time courses were remarkably similar. Only the H⁺-ATPase activity decreased monophasically with the age of mycelia. Membrane-bound proteases of both membrane fractions changed differently upon ageing. These results could not be explained as a consequence of nutrient starvation and indicate that the prolonged submerged cultivation triggers coordinated series of biochemical events which leads to the loss of growth competence.     

Biological treatments for the control of decay in tree wounds.: Field tests

In an attempt to control fungi causing decay a range of micro-organisms, selected after laboratory tests, was inoculated into wounds made in the trunks of beech trees. The most successful micro-organism was an isolate of Trichoderma viride, which, over a period of 4 years, maintained significantly lower colonisation by decay fungi at both sites - c. 15% of the level found in uninoculated wounds. T. viride could be reisolated from the majority of wounds into which it had been inoculated up to 4 years later. No other antagonist persisted very effectively. Inoculation of T. viride in glycerol improved its establishment but malt extract and sucrose had no such effect. Both the addition of glycerol to wounds and the wrapping of them in black PVC sheet increased natural colonisation by T. viride. The use of PVC but not glycerol reduced numbers of decay fungi but not through the agency of T. viride present by natural infection, as this proved generally ineffective in the control of decay fungi. Another isolate of T. viride persisted considerably better when covered with a wound sealant.     

Production of laccases by Pleurotus ostreatus in submerged fermentation in co‐culture with Trichoderma viride

Aims: To evaluate the production and stability of laccases by Pleurotus ostreatus in liquid co‐cultures with Trichoderma viride as a function of infection time and agitation rate. Methods and Results: Pleurotus ostreatus cultures were infected with T. viride spores at 30 and 48 h. Maximal laccase volumetric activity was seen after 48 h (control cultures) or 72 h (co‐cultures) of cultivation time. Only the cultures infected at 30 h showed an increased laccase volumetric activity compared to control cultures. After maximal laccase volumetric activity value was reached, a sharp decrease in it was observed in control cultures. Co‐cultures exhibited a comparatively lower loss of activity. The influence of P. ostreatus and/or T. viride on the stability of laccase volumetric activity and isoenzyme pattern was evaluated. Trichoderma viride induced changes in the laccase isoenzyme pattern. Agitated cultures increased biomass growth and specific productivity threefold and sevenfold, respectively, to the static cultures. Conclusions: The laccase volumetric activity is very likely the result of the balance between biosynthesis and degradation/biotransformation rates occurring during the cultures. The individual presence of P. ostreatus or T. viride in the culture negatively affected the volumetric laccase activity. Significance and Impact of the Study: The evaluation of culture parameters that could influence Trichoderma–basidomycetes interaction and laccase production during submerged fermentation has not been reported. This study showed how laccase production in co‐cultures of P. ostreatus and T. viride was influenced by the infection time and agitation/oxygenation conditions.     

Auswinterungsschäden in Raigras-Reinbeständen, die Bedeutung pilzlicher Krankheitserreger und ihre mögliche Eindämmung

Winterkilling in puresown ryegrass, the importance of fungal pathogens and possibilities for their control I. Results from field trials with natural infection Rotten plants, incomplete stands, a reduced number of shoots and a decline in dry matter yield were observed after hibernations of perennial and Italian ryegrass. Isolations from damaged plants showed that the main pathogen was the causal agent of snow mould Monographella nivalis (Schaffn.) E. Müll., asexual stage Gerlachia nivalis (Ces. ex Sacc.) W. Gams et E. Müll., synonym Fusarium nivale Ces. ex Sacc. The following fungi were also isolated: Laetisaria fuciformis(Mc Alp.) Burds., synonym Corticium fuciforme (Berk.) Wakef., Gibberella avenacea Cook, asexual stage Fusarium avenaceum (Fr.) Sacc. and Fusarium culmorum (W. G. Sm.) Sacc. The field trials were located at 440 and 630 m a.s.l. These elevations correspond to plain and mid-mountain climates, respectively. The tetraploid varieties ‘Lipo’, ‘Tetila’, ‘Citadel’ and ‘Bastion’ showed a higher level of resistance to snow mould compared to the diploid varieties ‘Ursus’, ‘Lemtal’, ‘Melino’ and ‘Pablo’. Tetraploid ryegrasses contaminated the soil with Gerlachia nivalis to a lesser extend than diploid ryegrasses. The influence of the date of cutting and of nitrogen fertilization in autumn on snow mould was also tested. Lowest values at both locations were observed when the last cutting occurred at the end of October. Severity was higher when the last cutting, took place earlier (mid September, end of September, mid October). Since parts of stands of the last cutting were strongly damaged by the cold, last cutting should take place in the middle of October, although infection with snow mould will not be as much reduced as if the last cutting was done at the end of October. The plant rotting caused by Gerlachia nivalis was increased with 80 kg N/ha in autumn compared with 40 kg N/ha.     

Alleviation of Fusarium oxysporum induced oxidative stress in wheat by Trichoderma viride

Trichoderma viride (Pers.) pre-inoculated wheat seedlings infected with Fusarium oxysporum Schlecht. (co-stressed) did not show wilting symptoms compared to Fusarium infected seedlings. Antagonistic activity of T. viride could be demonstrated against Fusarium infection by dual culture experiment. After seven days post infection, morphological and physiological parameters such as, root and shoot length, fresh and dry weight, relative water content, total soluble protein, total chlorophyll and carotenoid contents were observed to be increased in co-stressed compared to Fusarium infected seedlings. Accumulation of hydrogen peroxide was enhanced in Fusarium infected tissues compared to co-stressed. Trichoderma mediated activation of antioxidant enzymes such as, catalase, guaiacol peroxidase, ascorbate peroxidase, superoxide dismutase in co-stressed seedlings indicated their involvement in enhanced resistance against Fusarium infection, which is suggestive of playing crucial role in mitigating cellular toxicity developed due to excess H₂O₂. Thus, Trichoderma pre-inoculation protected wheat against Fusarium infection by stabilising oxidative stress.     

Enhancing biological control of basal stem rot disease (<Emphasis Type="Italic">Ganoderma boninense</Emphasis>) in oil palm plantations

Basal Stem Rot (BSR) disease caused by Ganoderma boninense is the most destructive disease in oil palm, especially in Indonesia and Malaysia. The available control measures for BSR disease such as cultural practices and mechanical and chemical treatment have not proved satisfactory due to the fact that Ganoderma has various resting stages such as melanised mycelium, basidiospores and pseudosclerotia. Alternative control measures to overcome the Ganoderma problem are focused on the use of biological control agents and planting resistant material. Present studies conducted at Indonesian Oil Palm Research Institute (IOPRI) are focused on enhancing the use of biological control agents for Ganoderma. These activities include screening biological agents from the oil palm rhizosphere in order to evaluate their effectiveness as biological agents in glasshouse and field trials, testing their antagonistic activities in large scale experiments and eradicating potential disease inoculum with biological agents. Several promising biological agents have been isolated, mainly Trichoderma harzianum, T. viride, Gliocladium viride, Pseudomonas fluorescens, and Bacillus sp. A glasshouse and field trial for Ganoderma control indicated that treatment with T. harzianum and G. viride was superior to Bacillus sp. A large scale trial showed that the disease incidence was lower in a field treated with biological agents than in untreated fields. In a short term programme, research activities at IOPRI are currently focusing on selecting fungi that can completely degrade plant material in order to eradicate inoculum. Digging holes around the palm bole and adding empty fruit bunches have been investigated as ways to stimulate biological agents.     

Inhibition of Pepper mild mottle virus with Commercial Cellulases

Pepper mild mottle virus (PMMoV) is one of the most important pathogens of pepper crops (Capsicum annuum L.) worldwide. We have found that commercial cellulases from Trichoderma reesei and Trichoderma viride strongly inhibit PMMoV infection of plants. When purified PMMoV was mixed with the cellulases, it greatly lost the capacity to induce local lesions on leaves of Nicotiana glutinosa. Pretreatment of sweet pepper leaves (C. annuum L.) with cellulase solutions before PMMoV inoculation greatly reduced the number of infected plants. These effects were superior to the effects of known viral inhibitors such as skim milk or Lentinula edodes culture filtrates. Although the mechanism of inhibition remains unknown, this is the first report of antiviral activity ascribed to commercially available cellulases.     

Inhibition of fungi,actinomycetes and bacteria by Stachybotrys atra

The effect ofStachybotrys atra on fungi, actinomycetes and bacteria was studied in agar culture. Of the 27 genera and 52 species of fungi, 6 species of actinomycetes and 5 genera and 10 species of bacteria tested,S. atra was found to inhibit 95.7 % fungi, all the actinomycetes and 83.3 % of bacteria.Aspergillus ustus, 2 unidentified species ofFusarium, Rhizobium trifolii andPseudomonas spp. were however not inhibited. In experiments in soil,S. atra inhibited the growth ofTrichoderma viride. S atra was ineffective whereT. viride andS. atra were inoculated simultaneously or whereT. viride was added 7 days earlier. Besides,S. atra was not found to controlMacrophomina phaseoli infection on cotton. Soil culture ofS. atra showed phytotoxic effect on cotton seedlings.S. atra produced a dark brown to black thermostable toxic metabolite in the medium. The culture filtrate retarded the growth ofM. phaseoli in agar culture. Despite the importance ofS. atra as a fungistatic agent with wide antimicrobial spectrum, the use ofS. atra as a protectant against plant pathogens seems to be limited because of its phytotoxicity on cotton.     

Chemosensory responses of Aporcelaimellus nivalis (Nematoda: Dorylaimida) towards kairomones emitted by prey nematodes belonging to different trophic groups

Abstract

Observations were made on the attraction of Aporcelaimellus nivalis towards kairomones/attractants emitted by prey nematodes belonging to different trophic categories, viz., saprophagous, epidermal, migratory semi-endodermal, predatory nematodes, virus vectors and cortical feeders. Aporcelaimellus nivalis responded positively and significantly to prey kairomones, but showed variation in their individual behaviour. Predators are most attracted towards epidermal feeders and least attracted to virus vectors. The differential responses of A. nivalis towards different prey were attributed to the inert behaviour of predators, their preference for a particular species of prey, chemical composition, concentration, quality, quantity of prey attractant, formation of minimum perceptible attraction gradient of prey and minimum response threshold of predators. Various factors such as prey density, period of prey incubation, starvation of predators, temperature, agar concentration, agar thickness and distance of predators from the source of attraction (prey) govern chemosensory responses of predator. Aporcelaimellus nivalis maximum response was towards Hirschmanniella oryzae, when tested as 10 day starved predators in agar plates containing 2 mm thick layer of 1% water-agar with 200 prey individuals previously incubated for 16 h at 30°C. Prey kairomones were most attractive when A. nivalis were tested from a distance of 2 and 3 cm.     

Effect of pH and Temperature on Enzyme Activity of Chitosanase Produced Under Solid Stated Fermentation by <Emphasis Type="Italic">Trichoderma</Emphasis> spp<Emphasis Type="Italic">.</Emphasis>

Trichoderma strains were extensively studied as biocontrol agents due to their ability of producing hydrolytic enzymes, which are considered key enzymes because they attack the insect exoskeleton allowing the fungi infection. The present work aimed to evaluate the ability of chitosanase production by four Trichoderma strains (T. harzianum, T. koningii, T. viride and T. polysporum) under solid stated fermentation and to evaluate the effect of pH and temperature on enzyme activity. pH strongly affected the enzyme activity from all tested strains. Chitosanase from T. harzianum and T. viride presented optimum activity at pH 5.0 and chitosanase from T. koningii and T. polysporum presented optimum activity at pH 5.5. Temperature in the range of 40–50°C did not affect enzyme activity. T. polysporum was found as the most promising strain to produce chitosanase with maximal enzyme activity of about 1.4 IU/gds, followed by T. viride (~1.2 IU/gds) and T. harzianum (1.06 IU/gds).     

Microbiota in Wheat Roots Evaluated by Cloning of ITS1/2 rDNA and Sequencing

Fungi (17 species), oomycetous organisms (four species of Pythium) and a plasmodiophorid (Polymyxa graminis) were recorded in wheat roots analysed by cloning of the total ITS1/2 rDNA and sequencing of representative clones. Roots of a fourth successive wheat crop were inhabited mostly by fungal pathogens including Gaeumannomyces graminis var. tritici, Monographella nivalis var. nivalis, Ophiosphaerella sp. and Helgardia anguioides. Roots of a first wheat crop were inhabited mostly by P. graminis and saprotrophic Pythium species. Results on fungal diversity and density were compared with those obtained by pure culture isolation and morphotyping. Only M. nivalis var. nivalis and H. anguioides were identifed in wheat roots by both the molecular and the pure culture isolation methods. New and additional evidence for the ecological roles of the species recorded is discussed.     

Trichoderma viride—Mediated Modulation of Oxidative Stress Network in Potato Challenged with Alternaria solani

Potato is a staple food crop cultivated globally. Heavy losses to potato production are reported annually due to soil borne phytopathogens. Trichoderma viride is a potential biocontrol agent that improves host defense. In the present study, potato tubers bio-primed with T. viride were studied for its effect on growth promotion and modulation of antioxidant system as well as defense-related enzymes in potato plants when challenged with Alternaria solani. Potato tubers treated with T. viride and after 45 days of sowing, plants were challenged with pathogen. Significant improvement in various growth parameters was recorded in bio-primed plants. While, in pathogen-challenged plants, an enhanced intracellular concentration of H₂O₂ and O₂^? was observed. Interestingly, T. viride when applied with pathogen, significantly improved the redox homeostasis by modulating the antioxidant enzyme activities. The significant induction of defense enzymes and free phenolic content suggested that T. viride-treated plants provide enhanced protection from oxidative stress induced during A. solani challenge via. elevated accumulation of antioxidant enzymes, polyphenolic compounds, and defense-related enzymes.

     

Potential for Biocontrol of Lasiodiplodia theobromae (Pat.) Griff. & Maubl. in Banana Fruits by Trichoderma Species

Fifteen Trichoderma isolates were tested for their antagonistic ability against Lasiodiplodia theobromae. Trichoderma harzianum exhibited the greatest inhibition in dual culture. Microscopic investigation demonstrated direct parasitism and coiling of T. harzianum and T. viride around hyphae of L. theobromae, causing swollen, deformed, shortened, or rounded cells of the pathogen. Granulation of cytoplasm and disintegration of the hyphal walls of L. theobromae also were noted in dual culture. Trichoderma viride reduced rotting by 29.07 to 65.06% in artificially inoculated banana fruits. Treatment of banana fruits with T. viride 4 h prior to inoculation with L. theobromae provided better protection than simultaneous application or treatment 4 h after inoculation.     

Chronic spearfishing may indirectly affect reef health through reductions in parrotfish bite rates

The grazing behaviour of two Caribbean parrotfish, a fished species, the stoplight parrotfish Sparisoma viride and a non-fished species, the striped parrotfish Scarus iseri, were studied in the presence (fished site) and absence (marine reserve) of chronic spearfishing activity. Diurnal feeding periodicity did not differ between the sites in either species: roving individuals had significantly higher bite rates in the afternoon, while territorial individuals foraged consistently throughout the day. Mean bite rate varied between sites in both species. Abundance, biomass and bite rates of S. viride were all significantly higher within the reserve, except for roving S. viride which had a higher mean bite rate in the afternoon outside the reserve compared with within it, attributable to maximisation of feeding in the afternoon when fishing risk was lower. Scarus iseri mean abundance and bite rate were greater outside the reserve, potentially because reduction in large territorial herbivores allowed S. iseri to feed more rapidly. By reducing the grazing potential of the remaining S. viride individuals the effect of fishing is greater than would be predicted from biomass changes alone. Less grazing by S. viride would not be compensated for by the increase in grazing by S. iseri because the latter feeds on different algae. Spearfishing of key parrotfish species reduces grazing potential directly by extraction and indirectly by changing behaviour.     

Investigations on the causes of upper stem rot (USR) on standing mature oil palms

Three different trials to examine the cause of upper stem rot (USR) infection in oil palm failed to achieve any infection. In the first experiment, inoculum was applied as colonised rubber wood blocks or as spore suspensions. In the second experiment, particular attention was given to ensure that the Ganoderma spores were freshly collected to maintain viability but no infection was observed around the inoculation sites of any of the different oil palm tissues treated. Lastly in the third experiment, both monokaryotic and dikaryotic mycelial cultures were applied directly to cut fronds, which were protected with a moist covering, but no infection was detected after more than two years. Failure to achieve infection by direct inoculation would indicate that USR does not arise from direct infection of living tissues by Ganoderma spores or mycelium, this is probably because of insufficient inoculum potential to cause infection. It is suggested that USR infection is achieved only when a sufficiently large source of inoculum has built up in dead material, probably in frond axils, and this allows invasion of the living tissues.     

Biocontrol potential of Trichoderma species against mango malformation pathogens

Malformation disease of Mango (Mangifera indica L.) caused by Fusarium moniliforme var. subglutinans is one of the most destructive diseases, which is a major production constraint in the mango-growing regions of India. In this study, The bioagents Trichoderma viride (Tr1), Trichoderma virens (Tr2) and Trichoderma harzianum (Tr3) were evaluated in culture with the pathogens to monitor the antagonistic effect and their volatile compound and culture filtrates (non-volatile compound). It was found that all the three isolates of bioagents significantly checked the growth of F. moniliforme var. subglutinans. In dual culture, the best result was obtained with T. harzianum followed by T. virens and T. viride. A similar result was also observed in the case of culture filtrates ofTrichoderma spp. The results clearly showed that inhibition of the growth of the fusaria isolates by T. harzianum was significantly superior to T. viride andT.virens. In case of antifungal activity of volatile compounds released by Trichoderma isolates, it was also observed that T. virens was more superior to T.harzianum and T. viride.     

Effects of Mixed-species Foraging Groups on the Feeding and Aggression of Juvenile Parrotfishes

Many parrotfishes (Scaridae) co-occur in mixed-species aggregations as juveniles, but diverge in resource use and social structure as adults. Focal observations of three juvenile parrotfishes (Scarus coeruleus, Sparisoma aurofrenatum, and Sparisoma viride) were conducted on inshore patch reefs in the Florida Keys to determine how feeding and aggressive interactions vary with group participation. All three species spent more time in groups than alone, most often in groups of less than ten individuals. Feeding rates were significantly higher for S. viride when foraging in groups than when alone. All species fed most often from Halimeda, and overall diet composition was similar for fish whether feeding in groups or alone. The frequency of aggressive interactions varied with group participation. Focal S. aurofrenatum were more aggressive when in groups than when alone, and both S. aurofrenatum and S. viride were attacked more often by damselfishes when they were alone than when in groups. In contrast, feeding rates, diet breadth, and aggressive interactions of S. coeruleus were less affected by group participation. Small mixed-species aggregations of coral reef fishes may be large enough for individuals to assume some of the benefits of group participation while at the same time avoiding the costs of competition realized in larger groups.