Showing papers on "Trichoderma harzianum published in 2003"
TL;DR: The development of Pseudomonas for the control of Pythium diseases in hydroponics and Pseudozyma flocculosa for theControl of powdery mildew by two Canadian research programs is presented.
Abstract: The controlled environment of greenhouses, the high value of the crops, and the limited number of registered fungicides offer a unique niche for the biological control of plant diseases. During the past ten years, over 80 biocontrol products have been marketed worldwide. A large percentage of these have been developed for greenhouse crops. Products to control soilborne pathogens such as Sclerotinia, Pythium, Rhizoctonia and Fusarium include Coniothyrium minitans, species of Gliocladium, Trichoderma, Streptomyces, and Bacillus, and nonpathogenic Fusarium. Products containing Trichoderma, Ampelomyces quisqualis, Bacillus, and Ulocladium are being developed to control the primary foliar diseases, Botrytis and powdery mildew. The development of Pseudomonas for the control of Pythium diseases in hydroponics and Pseudozyma flocculosa for the control of powdery mildew by two Canadian research programs is presented. In the future, biological control of diseases in greenhouses could predominate over chemical pesticides, in the same way that biological control of greenhouse insects predominates in the United Kingdom. The limitations in formulation, registration, and commercialization are discussed, along with suggested future research priorities.
582 citations
TL;DR: Analysis of isolates of Trichoderma spp.
209 citations
TL;DR: Results show that the antagonistic activity of HS93, LS674 and T. harzianum may be stimulated by chitin resulting in significant improvements in their effectiveness against pathogens.
Abstract: Two bacterial isolates and one strain of Trichoderma harzianum were tested alone and in combination with chitin for efficacy in control of root rot disease caused by Phytophthora capsici and Rhizoctonia solani in pepper plants under greenhouse conditions. These bacteria (Bacillus subtilis HS93 and B. licheniformis LS674) were isolated from repeatedly washed roots of pepper plants. In in vitro assays, HS93, LS674 and T. harzianum were antagonistic against P. capsici and R. solani and produced high levels of chitinase. Seed treatment and root drenching with bacterial suspensions of HS93 with 0.5% chitin was more effective against Phytophthora and Rhizoctonia root rot than addition of the organisms without chitin. LS674 and T. harzianum reduced Rhizoctonia but not Phytophthora root rot. In two greenhouse tests, seed treatment and root drenching with HS93 amended with chitin enhanced its biocontrol activity against P. capsici but not on R. solani. The effects of LS674 and T. harzianum against R. solani were significantly enhanced when they were used as suspensions with 0.5% chitin for root drenching, but this had no effect on P. capsici. In both greenhouse experiments, the use of 0.5% chitin alone for root drenching reduced Rhizoctonia root rot. Reduction of root rot disease was accompanied by increased yield. These results show that the antagonistic activity of HS93, LS674 and T. harzianum may be stimulated by chitin resulting in significant improvements in their effectiveness against pathogens.
157 citations
TL;DR: In this paper, the sexual state of Trichoderma harzianum has been linked unequivocally to its sexual state and its phylogeny has been studied in detail, but no diagnostic morphological distinctions were identified that justify formal taxonomic recognition for the different lineages.
154 citations
TL;DR: The results from this study indicate that several different approaches can be used at seeding to control Fusarium root and stem rot on greenhouse cucumber, and that the efficacy of the biological control agents was affected by seasonal differences in growing conditions, which affected the incidence and severity of the disease.
Abstract: Potential disease control methods were evaluated against root and stem rot of cucumber (Cucumis sativus) caused by Fusarium oxysporum f. sp. radicis-cucumerinum. Crab/shrimp shell chitin; three composted media; the biological control agents Pseudomonas chlororaphis strain 63-28, Trichoderma harzianum (RootShield Drench), Streptomyces griseoviridis (Mycostop), Gliocladium catenulatum (Prestop WP, Prestop Mix), and Trichoderma (Gliocladium) virens (SoilGard); and the fungicides thiram or benomyl were added at seeding time followed by inoculation with the pathogen. The addition of chitin (4%, vol/vol) to a peat-based medium significantly (P ≤ 0.05) enhanced seedling growth, increased soil pH, and reduced F. oxysporum f. sp. radicis-cucumerinum populations, but the severity of disease was increased. The addition of composted media (greenhouse compost, windrow composted dairy solids, and vermi-composted dairy solids) to the seeding cavity in a rock wool block medium, followed 48 h later by inoculation with F. oxysporum f. sp. radicis-cucumerinum, reduced seedling mortality when measured after 37 days. Greenhouse compost was significantly (P ≤ 0.05) more suppressive than the other two composts, and the suppression was partially eliminated by sterilization of the compost. The biological control agent G. catenulatum (formulated as Prestop WP and Prestop Mix) significantly reduced seedling mortality when it was applied at seeding 24 h prior to inoculation with the pathogen in the rock wool block medium. None of the other biological control agents reduced disease incidence when compared with control plants under these experimental conditions. Pseudomonas chlororaphis and the fungicide thiram both significantly reduced plant mortality at 17 and 24°C when pathogen-infested seed was treated, or when bacteria-treated and fungicide-treated seed were planted into pathogen-infested peat medium at 24°C. Under semicommercial propagation conditions, treatments consisting of Prestop WP, RootShield Drench, My-costop, and windrow composted dairy solids reduced the severity of disease caused by F. oxysporum f. sp. radicis-cucumerinum in two out of three trials. The efficacy of the biological control agents was affected by seasonal differences in growing conditions, which affected the incidence and severity of the disease. The results from this study indicate that several different approaches can be used at seeding to control Fusarium root and stem rot on greenhouse cucumber.
117 citations
TL;DR: The inhibitory activities of the compost-inhabiting microbes might partly be responsible for the efficacy of compost in reducing seedling blight diseases of crops.
Abstract: Compost-inhabiting bacteria were studied for their effect on seedling blight inducing pathogens. Aspergillus niger, Trichoderma harzianum, Bacillus cereus and Bacillus subtilis were the microbes found associated with cow dung, sawdust and rice husk composted soils. Sclerotium rolfsii, Fusarium oxysporum, Pythium aphanidermatum and Macrophomina phaseolina were isolated from blighted seedlings of Cowpea, while S. rolfsii, P. aphanidermatum, Helminthosporium maydis and Rhizoctonia solani were isolated from blighted maize seedlings. When these compost-inhabiting microbes were paired with the seedling blight inducing pathogens, T. harzianum grew on the mycelia of all the test fungal pathogens. B. cereus reduced the mycelia growth of Sclerotium rolfsii, F. oxysporum, P. aphanidermatum, H. maydis and R. solani, with inhibitory zones ranging from 35.5% to 53.3%. B. subtilis in culture also inhibited the mycelia growth of all tested pathogenic fungi with inhibitory zones of between 40.0% to 57.8%. The inhibitory activities of the compost-inhabiting microbes might partly be responsible for the efficacy of compost in reducing seedling blight diseases of crops.
(African Journal of Biotechnology: 2003 2(6): 161-164)
93 citations
TL;DR: Paecilomyces lilacinus showed the greatest potential for use in combination with selected fungicides and nematicides as part of an IPM programme for the control of PCN, but further work is required to confirm whether it is effective against PCN in soil.
87 citations
TL;DR: There was a significant decrease in Trichoderma spp.
77 citations
TL;DR: DsRed can be used as a highly effective vital marker in Ascomycetes and dual marked transformants expressed both DsRed-Express and GFP in the same mycelium and were used for non-quantitative comparison of the intensity of the fluorescence using confocal laser scanning microscopy.
Abstract: The recently reported red fluorescent protein DsRed from the reef coral Discosoma sp. represents a new marker that has been codon-optimized for high expression in mammalian cells. To facilitate expression of DsRed in ascomycete fungi, we used the clone pDsRed-Express (Clontech) for constructing a plasmid vector, pPgpd-DsRed, containing the constitutive Aspergillus nidulans glyceraldehyde 3-phosphate (gpd) promoter. This vector was used for co-transformation of Penicillium paxilli, Trichoderma harzianum and Trichoderma virens (syn. Gliocladium virens) together with either pAN7-1 or gGFP, both containing a gene for hygromycin resistance for transformant selection. In addition, gGFP contains a green fluorescent protein (GFP) gene for expression in Ascomycetes. Expression of DsRed-Express was obtained in all three fungi, indicating that DsRed can be used as a highly effective vital marker in Ascomycetes. Dual marked transformants expressed both DsRed-Express and GFP in the same mycelium and were used for non-quantitative comparison of the intensity of the fluorescence using confocal laser scanning microscopy.
77 citations
TL;DR: It is hypothesized that aggressiveness results from competition, antagonism, or parasitism but only as a component of, or following, extensive saprotrophic growth involving degradation of wheat straw cell walls.
Abstract: We examined the mycoparasitic and saprotrophic behavior of isolates representing groups of Trichoderma harzianum to establish a mechanism for the aggressiveness towards Agaricus bisporus in infested commercial compost. Mycoparasitic structures were infrequently observed in interaction zones on various media, including compost, with cryoscanning electron microscopy. T. harzianum grows prolifically in compost in the absence or presence of A. bisporus, and the aggressive European (Th2) and North American (Th4) isolates produced significantly higher biomasses (6.8- and 7.5-fold, respectively) in compost than did nonaggressive, group 1 isolates. All groups secreted depolymerases that could attack the cell walls of A. bisporus and of wheat straw, and some were linked to aggressiveness. Growth on mushroom cell walls in vitro resulted in rapid production of chymoelastase and trypsin-like proteases by only the Th2 and Th4 isolates. These isolates also produced a dominant protease isoform (pI 6.22) and additional chitinase isoforms. On wheat straw, Th4 produced distinct isoforms of cellulase and laminarinase, but there was no consistent association between levels or isoforms of depolymerases and aggressiveness. Th3's distinctive profiles confirmed its reclassification as Trichoderma atroviride. Proteases and glycanases were detected for the first time in sterilized compost colonized by T. harzianum. Xylanase dominated, and some isoforms were unique to compost, as were some laminarinases. We hypothesize that aggressiveness results from competition, antagonism, or parasitism but only as a component of, or following, extensive saprotrophic growth involving degradation of wheat straw cell walls.
75 citations
TL;DR: Two isolates of Trichoderma, which reduce the incidence of witches'broom disease caused in cocoa by Crinipellis perniciosa, were evaluated for their potential to produce hydrolases in liquid medium and except for N-acetylglucosaminidase and b- glucosidase Trichodma harzianum isolate 1051 produced the largest amounts of hydrolase.
TL;DR: The resulting medium contains the antimicrobials chloramphenicol, streptomycin, quintozene, and propamocarb and was highly selective, allowing the recovery of T. harzianum, as viable conidia and hyphal fragments, in compact colonies with the absence of visible microbial contaminants.
Abstract: We adapted a selective medium, previously developed for reisolation of Trichoderma spp. from soil, for quantitative determination of growth of T. harzianum from commercial Agaricus bisporus composts. This medium enables comparisons of aggressive (sensu inhibition of A. bisporus yield) with nonaggressive T. harzianum groups. The resulting medium contains the antimicrobials chloramphenicol, streptomycin, quintozene, and propamocarb and was highly selective, allowing the recovery of T. harzianum, as viable conidia and hyphal fragments, in compact colonies with the absence of visible microbial contaminants.
TL;DR: When G. mosseae co-inoculated with PGPRs enhances growth and nutrition of Ficus benjamina, T. harzianum and B. coagulans are designated as mycorrhizal helper organisms.
Abstract: A greenhouse investigation was conducted to study the influence of the arbuscular mycorrhizal (AM) fungus Glomus mosseae and the plant growth-promoting rhizomicroorganisms (PGPRs) Bacillus coagulans and Trichoderma harzianum on the growth and nutrition of micropropagated Ficus benjamina plantlets. The AM fungus was inoculated either singly or in combination with the PGPRs. Plants showed maximum plant height, biomass, P content, mycorrhizal root colonization, spore numbers and populations of T. harzianum and B. coagulans in root zone soil when all the three organisms were inoculated together. Thus, when G. mosseae co-inoculated with PGPRs enhances growth and nutrition of Ficus benjamina. T. harzianum and B. coagulans are thus designated as mycorrhizal helper organisms.
TL;DR: A metabolite produced by T. aggressivum isolates in vitro that inhibits growth of A. bisporus and other fungi is identified and likely has a inhibitory effect on the mycelia present in mushroom compost, resulting in devastating crop loss.
TL;DR: Results indicate that G. catenulatum, when applied as a preventative treatment, has the potential to significantly reduce root rot and damping-off caused by P. aphanidermatum on greenhouse cucumbers, under conditions of high disease pressure.
Abstract: Damping-off and root rot of greenhouse cucumbers grown in rock wool, caused by Pythium aphanidermatum, is a recurring problem for growers throughout the major production areas of Canada. Four commercially formulated biocontrol agents, Streptomyces griseoviridis strain K61 (Mycostop®), Trichoderma harzianum strain T-22 (RootshieldTM Drench), Trichoderma virens strain GL-21 (SoilGardTM 12G), and Gliocladium catenulatum strain J1446 (PrestopTM WP, Prestop mix) were evaluated in growth-chamber and greenhouse trials conducted over 2 years for efficacy against this disease. The agents were applied twice, once at seeding time and again 11 days later, as a drench (or incorporated into the sawdust medium for SoilGard). This was followed by inoculation with a P. aphanidermatum mycelial suspension 12 days after seeding. In growth-chamber trials conducted at 28–30 °C and 90% relative humidity, seedling mortality in the treatment receiving P. aphanidermatum alone was over 80%. Only G. catenulatum (Prestop WP) signific...
Journal Article•
TL;DR: Strain FJ1, a filamentous fungus isolated from rotten wood, showed high ability to hydrolyze cellulosic materials and utilized various cellulosics materials and organic nitrogen sources to produce cellulases and xylanase, and also considerably a crystalline and/or insoluble material like Avicel and rice straw.
Abstract: Strain FJ1, a filamentous fungus isolated from rotten wood, showed high ability to hydrolyze cellulosic materials. To identify the strain FJ1, ITS sequencing analysis and morphological observation were performed. The strain FJ I was identified as Trichoderma harzianum. The strain produced a large amount of CMCase, xylanase, β-glucosidase, and avicelase. Optimal culture conditions for the production of the enzymes, such as pH, temperature, and inoculation concentration, were initial pH 6.0-7.0, 25-30°C, and 10 4 ea-spores/ml in Mandel's medium, respectively. T harzianum FJ I utilized various cellulosic materials and organic nitrogen sources to produce cellulases and xylanase, and also considerably a crystalline and/or insoluble material like Avicel and rice straw. The highest levels of CMCase and xylanase were 41.2 and 65.6 U/ml in 7 days of cultivation using 2.5% of carbon source (Avicel+CMC) and 0.5% of nitrogen source (peptone), respectively.
TL;DR: The role of competition for nitrogen in interactions of pathogenic fungi and antagonists was investigated and the antagonistic fungi used nitrogen as ammonium at statistically significant higher rates during the first six days of cultivation than the phytopathogenic fungi.
TL;DR: Five microbial plant growth promoters or biocontrol agents were assessed for ability to proliferate on seeds of carrot, parsnip and leek and Comparisons were made between proliferation and survival in large-scale drum priming with post-priming application of microorganisms.
Abstract: Five microbial plant growth promoters or biocontrol agents (Pseudomonas fluorescens CHA0, Pseudomonas sp. AB842, Bacillus subtilis MBI600, Trichoderma harzianum T22 and T. virens G20) were assessed for ability to proliferate on seeds of carrot, parsnip and leek. In small-scale priming systems, both pseudomonads and MBI600 (when applied as cells) at levels between 105 and 106 cfu g−1 seed were able to colonise all seeds at the end of priming (240 h) despite initial poor recovery after addition of the cells in some cases. Pf CHA0 was a particularly aggressive seed coloniser often comprising the total pseudomonad population at the end of priming. Drying the seed after priming resulted in <1 log10 cfu g−1 seed loss for the pseudomonads but greater losses for MBI600 on carrot and leek seed. Application of spores of MBI600 resulted in little loss in cfu g−1 seed following addition of the cells and these levels were maintained throughout the priming period and after drying back. Both T22 and G20 were recovere...
TL;DR: Trichosetin, a tetramic acid-containing metabolite produced in the dual culture of Trichoderma harzianum and Catharanthus roseus (L.) G. Don callus, was subjected to phytotoxicity assays.
TL;DR: Control of leaf and head rot of Chinese cabbage (Brassica campestris L. ssp. pekinensis) was obtained by Clonostachys rosea (isolate IK726) in field trials conducted in 1995 and 1999 on naturally infested land in a commercial crop in Denmark.
Abstract: Control of leaf and head rot of Chinese cabbage (Brassica campestris L. ssp. pekinensis), caused by Pythium tracheiphilum, was obtained by Clonostachys rosea (isolate IK726) in field trials conducted in 1995 and 1999 on naturally infested land in a commercial crop in Denmark. A significant 2-3-fold disease reduction was obtained at an application rate of 108-109 conidia m−2 (high application rate) in both years, but not at a 10-fold reduced rate in 1999. Disease reduction by Trichoderma harzianum (Supresivit) was almost significant at the high application rate (1 g product m−2 corresponding to 7×109 colony forming units (CFUs) m−2) in both years, but not at a 10-fold reduced rate applied in 1999. In both 1995 and 1999 trials, the percentage of marketable heads increased significantly by 10% following a full application rate of C. rosea. Supresivit applied at the full application rate gave a significant 13% yield improvement in 1995 but not in 1999. No yield improvement was found when the two agents were a...
TL;DR: In this article, different microflora viz. Pleurotus sajor-caju, T. harzianum and A. chrocooccum were inoculated in different combinations into mixed solid waste, a mixture of municipal solid waste (MSW) and horticultural waste in the ratio of 70:30.
Abstract: To accelerate the process of composting, different microflora viz. Pleurotus sajor-caju (fungus), Trichoderma harzianum (fungus) and Azotobacter chroococcum (bacteria) were inoculated in different combinations into mixed solid waste, a mixture of municipal solid waste (MSW) and horticultural waste in the ratio of 70:30. The waste was decomposed for different time periods and then subjected to subsequent vermicomposting for a fixed period of one month. The compost produced was evaluated for nutrient levels and effects on mung bean (Vigna radiata) growth. A significant difference was observed in the quality of compost produced with the bioinoculants over control treatments where no bioinoculant was used. The combination of P. sajor-caju, T. harzianum and A. chrocooccum produced the highest quality compost. The percentage of mycorrhizal infection in mung bean was influenced by the three inoculants and crop growth was enhanced significantly with the combination of P. sajor-caju, T. harzianum and A. chrocooccum over other treatments.
TL;DR: Improvement of mushroom resistance to Trichoderma aggressivum could be obtained by inducing reaction mechanisms before contact with the pathogen and whether this ability was species or strain dependent.
Abstract: Trichoderma spp. is the cause of green mold, a disorder that affects cultivated mushrooms. The aims of the study were to establish whether im- provement of mushroom resistance to Trichoderma aggressivum could be obtained by inducing reaction mechanisms before contact with the pathogen and whether this ability was species or strain dependent. Twenty nine isolates of Agaricus bisporus, 29 isolates of Lentinula edodes and 18 isolates of Pleurotus spp. were studied. The effect of T. harzianum metabolites on mycelial growth of these isolates was evaluated on YMEA (yeast, malt extract and agar), supplemented or not with Lysing Enzymes from T. harzianum (Sig- mat, L1412). Mycelial growth generally was affected by Lysing Enzymes, but some L. edodes and Pleurotus spp. adapted to Lysing Enzymes. When mycelium was taken from a first culture with Lysing Enzymes and placed on YMEA with Lysing Enzymes for a second culture, their growth rate was not different from those of the controls. In the case of A. bisporus, only partial adaptation was obtained with a few isolates. The effect of adaptation to Lysing Enzymes on resis- tance to T. aggressivum was assayed for one strain of each group. Trichoderma aggressivum was exposed to the margin of 5- to 9-day-old mushroom colonies. Agaricus bisporus produced brown droplets, and T. aggressivum overgrew its mycelium. Lentinula edodes and P. ostreatus produced brown lines blocking the progression of T. harzianum, both on YMEA and YMEA plus Lysing Enzymes. The line was visible after 3 d on YMEA and after only 2 d on YMEA plus Lysing Enzymes. Improvement in the resistance to antago- nists by introduction of some of their metabolites to the culture medium is a method for mushroom pro- tection.
TL;DR: The results of the present study showed that the combinations of P/A, P/PC and A/PC showed compatible growth and the rest of the combinations (P/T, A/T and T/PC) were incompatible cultures.
Abstract: The filamentous fungal strains such as Penicillium corylophilum (P), Aspergillus niger (A), Trichoderma harzianum (T) and Phanerochaete chrysosporium (PC) isolated from its relevant sources (wastewater, sewage sludge and sludge cake) were selected for compatible/incompatible mixed cultures. Six combinations of P. corylophilum and A. niger (P/A); P. corylophilum and P. chrysosporium (P/PC); P. corylophilum and T. harzianum (P/T); A. niger and T. harzianum (A/T); A. niger and P. chrysosporium (A/PC); T. harzianum and P. chrysosporium (T/PC) were used to evaluate their potential performance as compatible/incompatible mixed culture for the treatment of municipal wastewater sludge in a bioconversion process. The results of the present study showed that the combinations of P/A, P/PC and A/PC showed compatible growth and the rest of the combinations (P/T, A/T and T/PC) were incompatible cultures. A maximum production of dry biomass and dry filter cake were recorded in the compatible mixed culture of P. corylophilum and A. niger (P/A). A maximum reduction of COD (90%) and a decreased filtration time of treated sludge was observed in the case of P/A microbial mixed culture. The pH value was also affected by the fungal cultures. Effective results were observed by using microbial mixed culture after four days of treatment compared to other treatments (2 and 6 days).
TL;DR: Most Trichoderma isolates significantly reduced the incidence of disease compared with the infected control, and Bacillus subtilis was also effective against sharp eyespot, although less active than Trichodma spp.
Journal Article•
TL;DR: Seven efficient phosphatase producing fungi were isolated and identified and Trichoderma harzianum was found to be most efficient organic P mobilizer as compared to the other fungi, tested.
Abstract: Seven efficient phosphatase producing fungi (PPF) were isolated and identified as Aspergillus rugulosus, A. fumigatus, A. terreus, A. niger, A. parasiticus, Pseudeurotium zonatum and Trichoderma harzianum. Their efficiency to hydrolyze different compounds of organic phosphorus (mono- and hexa-) was examined. The fungi reduced the pH of the medium, which was maximum with A. niger. A significant negative correlation of pH with development of fungal mats was observed (r = -0.39, n = 28, p < 0.05). The maximum secretion of acid phosphatase by PPF was at 21 d and alkaline phosphatase at 14 d. Acid phosphatase produced by PPF was three times higher than alkaline phosphatase. The intracellular phosphatase activity was significantly higher than extracellular activity. The efficiency to hydrolyse mono-phosphate by phosphatases released from the PPF was 4-times higher than hexa phosphate. T. harzianum was found to be most efficient organic P mobilizer as compared to the other fungi, tested. The efficiency per unit of enzyme produced by different fungi was different and that indicated the isoenzymes being of different types.
Journal Article•
TL;DR: It was concluded that 1% xylan concentration is suitable for high xylanase production rate and agitation during growth was suitable for efficient production.
Abstract: In this study, different Trichoderma strains were tested and Trichoderma harzianum 1073 D3 was found to be the most potent xylanase producer. Then some cultural parameters, namely, incubation time, substrate concentration, initial culture pH and temperature were optimized in order to increase xylanase production from Trichoderma harzianum 1073 D3. The optimum incubation time was found to be 13 days. It was concluded that 1% xylan concentration is suitable for high xylanase production rate. The optimum temperature and pH were found to be 30 degrees C and 7, respectively. Also, it was determined that agitation during growth was suitable for efficient production.
TL;DR: Results indicate that nutrient-induced changes preceding germination in Trichoderma conidia can either enhance or decrease their biological control potential, depending on environmental conditions in the microhabitat.
Abstract: Trichoderma biocontrol isolates are most effective as highly concentrated inocula. Their antagonism to other fungi may be a result of pregermination respiration. In a nutrient-rich medium, almost all Trichoderma atroviride P1 (P1) conidia initiated germination processes and increased respiration, even in dense suspensions. When 1 x 10(7) P1 conidia/ml were coinoculated with 1 x 10(5) Botrytis cinerea conidia/ml, dissolved oxygen fell to /= 0.97, P < 0.01). After initiating germination, Trichoderma conidia became more sensitive to desiccation and were killed by drying after only 2 h of incubation on a nutrient-rich substrate at 23 degrees C. These results indicate that nutrient-induced changes preceding germination in Trichoderma conidia can either enhance or decrease their biological control potential, depending on environmental conditions in the microhabitat.
TL;DR: The apparent Km values on soluble and insoluble xylans from oat spelt showed that xylan-degrading enzymes from A. niger, T. longibrachiatum and P. corylophilum were most active on the soluble form, while dithiothreitol improved the half-lives of these enzymes at 50 ◦ C and 60 ◦C.
TL;DR: Lower plant density increased the incidence of disease in an infected field, and is therefore not considered to be a viable form of cultural control.
Abstract: Sclerotium rolfsii Sacc. causes disease of numerous crop plants worldwide, including groundnuts. Control of this pathogen is difficult as it produces sclerotia which overwinter in the soil to emerge as inoculum and cause disease the following season. Various chemical, biological and cultural control strategies have been suggested and implemented, some of which have reduced disease incidence in the field. No studies have yet been undertaken in South Africa to control this disease on groundnut, either chemically, biologically or by cultural practices. In this study, several strategies were investigated for the control of S. rolfsii on groundnuts. Difenoconazole was identified as a fungicide that could possibly be applied in combination with Trichoderma harzianum, a biological antagonist of S. rolfsii, above carbendazim and flusilazole, and chlorothalonil. Difenoconazole significantly reduced the growth rate of S. rolfsii but not of T. harzianum. The cultivation of infected fields with an inversion plough significantly reduced infection of groundnuts by S. rolfsii and also improved the quality of the produce, while yield was not increased. Lower plant density increased the incidence of disease in an infected field, and is therefore not considered to be a viable form of cultural control.