Antagonistic microorganisms and nitrogen fertilization in control of tomato southern blight

The present study assessed the efficacy of formulated biocontrol agents and nitrogen fertilization on southern blight control. Antagonism test in vitro was performed to assess the inhibitory activity of Bacillus methylotrophicus and Trichoderma asperellum against the growth of Sclerotium rolfsii. Tomato seedlings were transplanted into the substrate added with ammonium nitrate doses and inoculated with the formulated biocontrol agents Ônix (B. methylotrophicus) or Quality (T. asperellum). Subsequently, seedlings were inoculated with S. rolfsii. Plant mortality, shoot and root weight were assessed 11 days after the last inoculation. Agents had effective inhibitory activity against S. rolfsii; thus, they could reduce southern blight severity when combined with ammonium nitrate. However, plant mortality was not reduced by them.(AU)

Identification and biological characteristics of southern blight causing root rot on three medicine plants of Iridaceae in Dabie Mountains / 中国中药杂志

In order to identify the species and biological characteristics of the pathogen of southern blight from three kinds of Chinese medicine of Iridaceae(Belamcanda chinensis, Iris tectorum and I. japonica) in Dabie Mountains, the isolation, identification, pathogenicity and biological characteristics of the pathogens were studied according to Koch's postulates. In addition, 9 chemical fungicides, 3 botanical fungicides and 5 microbial fungicides were used to evaluate their inhibition to the isolates in vitro. The results showed that all the strains(SG-Q, YW-Q, and HDH-Q) isolated and purified from the diseased plants of B. chinensis, I. tectorum and I. japonica, respectively, were identified as Sclerotium rolfsii through morphological observation and sequence aligement of 18 S rDNA, rDNA-ITS and TEF. Field observations showed that the intensity of the disease incidence of three Iridaceae plants was B. chinensis>I. japonica> I. tectorum, and the pathogenicity of the strains was SG-Q>YW-Q>HDH-Q. For biological characteristics, SG-Q strain was suitable for growth under the 12 h light/12 h dark cycle, with the optimal growth temperature of 30 ℃ and pH of 5. Among the 9 tested chemical fungicides, 29% lime sulphure and 10% flusilazole had stronger inhibitory effect on mycelia growth of SG-Q. For 3 botanical fungicides, 1% osthol, 20% eugenol and 0.5% berberine could effectively inhibt the mycelial growth of SG-Q and cause the morphological variation of the pathogen. For 5 microbial fungicides, Trichoderma harzianum and Bacillus subtilis had better inhibition on the mycelium growth of SG-Q.

Discovery and functional verification of endogenous glucanases for scleroglucan hydrolysis in Sclerotium rolfsii / 生物工程学报

Scleroglucan is a high-molecular water-soluble microbial exopolysaccharide and mainly applied in the fields of petroleum, food, medicine and cosmetics. The high molecular weight of scleroglucan produced by microbial fermentation leads to low solubility, high viscosity and poor dispersibility, thus bringing a series of difficulties to extraction, preservation and application. It is important to explore suitable degradation method to adjust the molecular weight of scleroglucan for expanding its industrial application. Taking Sclerotium rolfsii WSH-G01 as a model strain, in which functional annotations of the glucanase genes were conducted by whole genome sequencing. Based on design of culture system for culture system for differential expression of β-glucanase, endogenous β-glucanase genes in S. rolfsii WSH-G01 were excavated by transcriptomics analysis. Functions of these potential hydrolases were further verified. Finally, 14 potential endogenous hydrolase genes were obtained from S. rolfsii. After heterologous overexpression in Pichia pastoris, 10 soluble enzymes were obtained and 5 of them had the activity of laminarin hydrolysis by SDS-PAGE and enzyme activity analysis. Further investigation of the 5 endogenous hydrolases on scleroglucan degradation showed that enzyme GME9860 has positive hydrolysis effect. The obtained results provide references not only for obtaining low and medium molecular weight of scleroglucan with enzymatic hydrolysis, but also for producing different molecular weight of scleroglucan during S. rolfsii fermentation process with metabolic engineering.

Screening of endophytic fungi against southern blight disease pathogen-Sclerotium delphinii in Dendrobium catenatum / 中国中药杂志

In order to screen the endophytic fungi that can enhance the host(Dendrobium catenatum) resistance to Sclerotium delphinii, the antagonism between each of the 43 endophytic fungi and the pathogen S. delphinii were tested. The results showed that 6 endophytic fungi(DCR2, DCR5, DCR21, DCR22, DCR42, DCR43) have strong activities against the pathogen, the inhibition rates were 49.2%, 49.2%, 47.2%, 56.2%, 53.2%, 48.0%, respectively. Then D. catenatum plantlets were inoculated with both S. delphinii and each of these six endophytic fungi. As a result, the incidence rates of leaves and stems of the D. catenatum plantlets inoculated with DCR2 and the pathogen were both significantly lower than those with other treatments, and the plantlet death rate was 0. It showed that DCR2 Trichoderma polysporum could effectively inhibit the southern blight disease of D. catenatum. Through the endophytic fungal re-isolation test, it was found that DCR2 can colonize in the roots, stems, and leaves of D. catenatum. The research will provide new ideas for the prevention and treatment of the southern blight disease of D. catenatum. It is also significant for reducing pesticide use, ensuring food safety, and promoting the sustainable development of D. catenatum industry. Furthermore, it will provide a basis for the disease control in other crops.

Occurrence regularity of Dendrobium catenatum southern blight disease / 中国中药杂志

In order to scientifically prevent and control Dendrobium catenatum southern blight disease,the main factors related to this disease occurrence,the pathogen( Sclerotium delphinii),environmental factors( temperature and humidity) and D. catenatum germplasms,were investigated. The results showed that reaching 25-30 ℃ temperature and over 95% humidity simultaneously should be the main conditions for the occurrence and prevalence of D. catenatum southern blight disease. Moreover,the S. delphinii-infected plants and their contaminated substrates were the disease spreading sources. Therefore,removing the infected plants,dealing with the contaminated substrates,keeping air ventilation,and reducing air humidity are the effective ways to prevent and control the occurrence and prevalence of D. catenatum southern blight disease. The research also indicated that D. catenatum has different resistances to the southern blight disease depending on germplasm. The present study lays important foundations for the breeding of D. catenatum diseaseresistant varieties and the further analysis of the infection and resistance mechanisms underlying southern blight disease.

Primera descripción de Sclerotium coffeicola en caoba africana en México / First description of Sclerotium coffeicola on African mahogany in Mexico

Una enfermedad foliar fue detectada en la plantación comercial de Khaya senegalensis con 3 anos de edad, en la localidad de Huimanguillo (Tabasco, México). Mediante la caracterización morfológica y molecular, y por el cumplimiento de los postulados de Koch, se determinó que el agente causal corresponde al hongo Sclerotium coffeicola. Este es el primer reporte de S. coffeicola causando mancha foliar en caoba africana en México.

A foliar disease was detected in the commercial plantation of Khaya senegalen with three years of age in Huimanguillo, Tabasco, Mexico. Through the morphological and molecular characterization and the compliance of the Koch's postulates, it was concluded that the causal agent corresponds to the fungus Sclerotium coffeicola. This is the first report of S. coffeicola causing leaf spot on African mahogany in Mexico.

Evaluation of the fungitoxic activity of vegetal extracts on the mycelial growth of phytopathogens / Avaliação da atividade fungitóxica de extratos vegetais sobre o crescimento micelial de fitopatógenos

Although the productivity of common bean in Tocantins is economically favorable, it has been infected by various pathogens found in soil. Among the major diseases is the web blight and root rot caused by Rhizoctonia solani and collar rot caused by the fungus Sclerotium rolfsii. This study aimed to evaluate the fungitoxic activity of methanol extracts of eight plant species on the inhibition of mycelial growth of S. rolfsii and R. solani. The fungitoxic activities were carried out over the inhibition of mycelial growth by means in vitro assays. The extracts were applied in concentrations of 250, 500, 1000, 2500 e 5000 µg ml-1 in PDA culture medium. In bioassays, it was found the significant effect of plant, concentration and also their interaction on the antifungal activity of the extracts. However, some extracts showed no inhibition of mycelial growth of the pathogens studied. Among those who had higher inhibitions is the extract of Lantana trifolia, which inhibited the mycelial growth of S. rolfsii in all concentrations, being the same as 97% for the highest concentration. When the methanol extract of Piper amplum Kunth, inhibition of the highest concentration was 83% for S. rolfsii and 74% for R. solani. These results show the potential of methanolic extract of Lantana trifolia and Piper amplum Kunth in the control set of plant pathogens studied.

Apesar da produtividade do feijão comum no Tocantins ser economicamente favorável, o mesmo pode ser infectado por vários patógenos habitantes do solo, dentre as principais doenças encontra-se a mela e a podridão radicular causadas pelo fungo Rhizoctonia solani e a podridão do colo causada pelo fungo Sclerotium rolfsii. Este trabalho teve como objetivo avaliar a atividade fungitóxica dos extratos metanólicos de oito espécies vegetais sobre a inibição do crescimento micelial de Sclerotium rolfsii e Rhizoctonia solani. As atividades fungitóxicas foram realizadas perante a inibição do crescimento micelial por meio de ensaios in vitro, sendo os extratos aplicados nas concentrações de 250, 500, 1000, 2500 e 5000 µg ml-1 em meio de cultura BDA. Observou-se o efeito significativo dos fatores planta, concentração e também da interação destes sobre as atividades fungitóxicas. No entanto, alguns extratos não apresentaram inibição do crescimento micelial dos fitopatógenos estudados. Entre os que apresentaram maiores inibições encontra-se o extrato de Lantana trifolia, que inibiu o crescimento micelial do S. rolfsii em todas as concentrações, sendo o mesmo de 97% para a maior concentração. Já a concentração mais elevada do extrato metanólico de Piper amplum apresentou inibição de 83% sobre o crescimento micelial de S. rolfsii e 74% sobre o crescimento micelial de R. solani. Tais resultados evidenciam a potencialidade dos extratos metanólicos das folhas de Lantana trifolia e de Piper amplum no controle dos fitopatógenos estudados.

Phylogenetic Placement and Morphological Characterization of Sclerotium rolfsii (Teleomorph: Athelia rolfsii) Associated with Blight Disease of Ipomoea batatas in Korea

In this study, we aimed to characterize fungal samples from necrotic lesions on collar regions observed in different sweetpotato growing regions during 2015 and 2016 in Korea. Sclerotia appeared on the root zone soil surface, and white dense mycelia were observed. At the later stages of infection, mother roots quickly rotted, and large areas of the plants were destroyed. The disease occurrence was monitored at 45 and 84 farms, and 11.8% and 6.8% of the land areas were found to be infected in 2015 and 2016, respectively. Fungi were isolated from disease samples, and 36 strains were preserved. Based on the cultural and morphological characteristics of colonies, the isolates resembled the reference strain of Sclerotium rolfsii. Representative strains were identified as S. rolfsii (teleomorph: Athelia rolfsii) based on phylogenetic analysis of the internal transcribed spacer and large subunit genes along with morphological observations. To test the pathogenicity, sweetpotato storage roots were inoculated with different S. rolfsii strains. ‘Yulmi’ variety displayed the highest disease incidence, whereas ‘Pungwonmi’ resulted in the least. These findings suggested that morphological characteristics and molecular phylogenetic analysis were useful for identification of S. rolfsii.

The improvement of competitive saprophytic capabilities of Trichoderma species through the use of chemical mutagens

Abstract The antagonistic potential of Trichoderma strains was assayed by studying the effect of their culture filtrate on the radial growth of Sclerotium rolfsii, the causal agent of chickpea collar rot. Trichoderma harzianum-1432 (42.2%) and Trichoderma atroviride (40.3%) were found to be strong antagonists. To enhance their antagonistic potential, mutagenesis of these two selected strains was performed. Two mutants, Th-m1 and T. atroviride m1, were found to be more effective than their parent strains. The enzymatic activities of the selected parent and mutant strains were assayed, and although both mutants were found to have enhanced enzymatic activities compared to their respective parent strains, Th-m1 possessed the maximum cellulase (5.69 U/mL) and β-1,3-glucanase activity (61.9 U/mL). Th-m1 also showed high competitive saprophytic ability (CSA) among all of the selected parent and mutant strains, and during field experiments, Th-m1 was found to successfully possess enhanced disease control (82.9%).

Chemical and biological control of Sclerotinia stem rot in the soybean crop / Controle químico e biológico da podridão branca da haste na cultura da soja

It was evaluated the effect of fungicides and the microbial control agent Trichoderma harzianum on the inhibition of the carpogenic and ascospore germination of Sclerotinia sclerotiorum. This study also evaluated the chemical, fungicidal and microbial control of white mold or Sclerotinia stem rot of soybean in the field. Three experiments were conducted, as follows: 1) inhibition of carpogenic germination of sclerotia, 2) inhibition of ascospore germination, and 3) control of Sclerotinia stem rot in a soybean crop under field conditions. The treatments evaluated were fluazinam, procymidone, iprodione, thiophanate-methyl, carbendazim, benzalkonium chloride + fluazinam, and T. harzianum. Procymidone resulted in an inhibition of 13.5% and benzalkonium chloride in an inhibition of 13.9% in an ascospore germination test. Fluazinam and procymidone were the most effective in reducing the production of ascospores/apothecium, representing 65.6% and 82.4% of inhibition. Procymidone and fluazinam if combined or not with benzalkonium chloride were the most effective in controlling sclerotinia stem rot under field conditions when applied at the onset of flowering and 15 days later. In the 2009-10 harvest, these two fungicides reduced the incidence of Sclerotinia stem rot by 73.1 and 71.6% and in the 2010-11 harvest by 75.7 and 77.6%, respectively.

Avaliaram-se o efeito de fungicidas e agente de controle biológico Trichoderma harzianum na inibição da germinação carpogênica e de ascósporos de Sclerotinia sclerotiorum. Também foram avaliados os controles químico e biológico do mofo branco ou podridão branca da haste na cultura da soja em condições de campo. Foram desenvolvidos três ensaios, sendo: 1) inibição da germinação carpogênica; 2) inibição da germinação de ascósporos; e 3) controle da podridão branca da haste na cultura da soja em condições de campo. Os tratamentos avaliados foram fluazinam, procimidona, iprodione, tiofanato metílico, carbendazim, cloreto de benzalcônio + fluazinam e T. harzianum. O procimidona resultou em inibição de 13,5% e o cloreto de benzalcônio + fluazinam em 13,9% de inibição no teste de inibição da germinação dos ascósporos. Fluazinam e procimidona foram os mais eficientes na redução da produção de ascósporos/apotécio representando 65,6% e 82,4% de inibição. O procimidona e fluazinam se combinados com cloreto de benzalcônio ou não foram os mais eficientes no controle da podridão branca da haste em condições de campo, quando aplicados no início do florescimento e 15 dias após. Na safra 2009-10, esses dois fungicidas reduziram a incidência da podridão branca da haste, em 73,1 e 71,6% e, na safra 2010-11, reduziram em 75,7 e 77,6%, respectivamente.

Optimizing culture conditions for the antagonistic activities of Trichoderma viride against Sclerotium rolfsii causative agent of southern blight disease of tomato

Aims: Sclerotium rolfsii is a pathogen of agricultural crops such as tomatoes. Trichoderma viride has been shown to control this pathogen effectively but the optimum conditions of this biocontrol agent need to be determined. This piece of research was therefore aimed at studying the conditions that could be maintained in maximizing the full potential of T. viride. Methodology and results: Malt extract agar was separately supplemented with different carbon sources (glucose, sucrose, maltose, lactose, and mannitol), nitrogen sources (peptone, ammonium nitrate, zinc nitrate and sodium nitrate) as well as salts (NaCl, CaCl2, KI, BaCl2) at different concentrations. Effect of different temperature and pH ranges was also evaluated. All the carbon used supported the growth of both S. rolfsii and T. viride at all concentrations. The growth of S. rolfsii was less than 90 mm at 3% of all the carbon used compared to the plates in which no carbon sources were added whereas the growth of T. viride was 90 mm. There were morphological changes in the growth of both T. viride and S. rolfsii with increase in concentrations of peptone and ammonium nitrate. The greenish colour of T. viride was completely lost while S. rolfsii became fluffier. For peptone, the percentage reduction ranged from 68.52 to 63.33 while for zinc nitrate and sodium nitrate, the percentage reduction ranged from 85.19 to 80.74 and 55.00 to 43.70 respectively. Also, there was increase in antagonistic property of T. viride with the inclusion of salts (NaCl, CaCl2 and KI) at all concentrations used. However, barium chloride was toxic to T. viride at 2-5% (w/v). The optimum temperature and pH for the antagonistic property of T. viride appeared to be 37 °C and 6.0 respectively. Conclusion, significance and impact of study: Inclusion of different carbon, nitrogen and salts increased the antagonistic activities of T. viride against S. rolfsii although lactose appeared to be the best carbon source while zinc nitrate and CaCl2 were the best nitrogen and salt respectively. Barium chloride was toxic to T. viride at 2-5% (w/v).

Potential of Microbispora sp. V2 as biocontrol agent against Sclerotium rolfsii, the causative agent of southern blight of Zea mays L (Baby corn)–in vitro studies.

The study was undertaken with the aim of exploring novel and beneficial agro activities of rare actinomycetes like Microbispora sp. V2. The antagonistic activity of Microbispora sp. V2 was evaluated as a biocontrol agents against Sclerotium rolfsii, a soil-borne fungal plant pathogen. The methodology performed for evaluation of biocontrol agent was in vitro evaluation assay which comprised of three tests viz., cellophane overlay technique, seed germination test and Thiram (fungicide) tolerance of Microbispora sp. V2. The isolate was found to inhibit the fungal pathogen Sclerotium rolfsii to 91.43% in cellophane assay. In seed germination assay, Microbispora sp. V2 treated seeds resulted in 25.75% increased germination efficiency, as compared to seeds infected by Sclerotium rolfsii. The isolate Microbispora sp. V2 could tolerate 1000 µg mL-1 of Thiram (fungicide). The in vitro assay studies proved that Microbispora sp. V2 can be used as antifungal antagonist and thus posses’ great potential as biocontrol agent against southern blight caused by Sclerotium rolfsii in Zea mays L (Baby corn) which causes large economical losses.

Nature and flavor pharmacology of Fuling and its components for learning and memory improvement as well as sedative and hypnotic effects / 中草药

Objective: To evaluate the activities of Fuling (the dried sclerotium of Poria cocos) and its components, then its nature and flavor were attributed by traditional Chinese medicine (TCM) theory. Methods: Scopolamine was used to cause learning and memory impairment in mice, and Morris water maze test was used to observe the effects of Fuling and its components on learning and memory of mice, and shaking cage method and pentobarbital sodium were used to evaluate the sedative and hypnotic effects of Fuling and its components. Results: Water decoction of Fuling (crude drug 8.56 g/kg), ethyl acetate, petroleum ether, crude polysaccharides, and refined polysaccharides components could significantly shorten the latency of scopolamine-induced memory impairment in mice to reach the platform; Acetylcholinesterase activity in mice brain was decreased, the effects of the components washed with alcohol and water on latency were less obvious and the individual components of the cerebral index showed an increase in different proportions; Crude drug (42.8 g/kg) water decoction of Fuling could significantly prolong the sleeping time, but had no effect on sleep latency; Crude polysaccharides could significantly shorten the sleep latency while the refined polysaccharides could significantly increase sleeping time; Followed by ethyl acetate components, the petroleum ether components showed a weak antagonistic effect. Conclusion: The learning and memory improvement as well as the sedative and hypnotic effects are associated with Fuling's sweet taste which can tonify spleen to calm nerves; The ethyl acetate, petroleum ether, and polysaccharides components are the basic materials of sweet taste.

Evaluation of Trichoderma SPP. Against Sclerotium Rolfsii In Vitro.

To evaluate the effect of Trichoderma spp. on radial growth of Sclerotium rolfsii, three species of Trichoderma viz., Trichoderma viride, Trichoderma harzianum and Trichoderma longibrachiatum were selected. The results from this experiment revealed that T. viride (TvL), T. harzianum 4 (Th 4) and T. harzianum 14 (Th14) isolates were found effective and showed lowest radial growth of 3.50 cm and highest per cent inhibition (56.25%) of S. rolfsii but were statistically on par with each other. The highest radial growth (4.23 cm) and lowest per cent inhibition (47.1%) were recorded with T. longibrachiatum (Tl2). Results from non-volatile assay indicated that irrespective of concentration, culture filtrate of T. viride (TvL) was found to be most effective; recorded lowest radial growth and highest per cent inhibition followed by T. harzianum 14 (Th14) and T. harzianum 4 (Th4).

Effect of Plant Extracts on Radial Growth of Sclerotium Rolfsii Sacc. Causing Stem Rot of Groundnut.

To evaluate certain plant extracts on development of Sclerotium rolfsii causing stem rot in groundnut, we conducted an in vitro experiment in Department of Plant Pathology, Agricultural College, Bapatla. For this, we selected eight plant species viz., Ashoka (Polyalthia longifolia), Garlic (Allium sativum), Ginger (Zingiber officinalis), Neem (Azadirachta indica), Seetha Phal (Annonas squamosa), Tulasi (Ocimum sanctum), Milk weed (Calotropis gigantean) and Peri Winkle (Vinca rosea) and are tested at 10% concentration. Among these plant extracts, clove extract of garlic was most effective and recording lowest mycelial growth (0.0 cm) and highest per cent inhibition (PI) (100%) in both sterilized and un-sterilized conditions. In sterilized condition, garlic followed by tulasi (4.62 cm, 48.70 PI) and neem (7.38 cm & 17.9 PI) were recorded the lowest mycelial growth and highest per cent inhibition over control, respectively. In un-sterilized condition, garlic followed by ginger (2.43 cm & 72.96 PI) and tulasi (2.52 cm & 72.04 PI) were recorded the lowest mycelia growth and highest per cent inhibition over control, respectively.

Effect of Bio-Control Agents on Radial Growth of Sclerotium Rolfsii In Vitro.

To know the efficacy of bio-control agents on growth of Sclerotium rolfsii causing stem rot of groundnut, an in vitro study was conducted in the Department of Plant Pathology, Agricultural College, Bapatla. For this, three Trichoderma spp., two Pseudomonas fluorescens isolates and one Bacillus subtilis were selected as biocontrol agents. We observed that, there is a significant difference among all the treatments. The lowest radial growth (1.9 cm) and highest per cent inhibition (79.26%) were recorded with T. viride PDBC isolate followed by T. harzianum 4 (2.3 cm and 74.81%) and Trichoderma harzianum PDBC (2.6 cm and 70.74%) isolates, respectively. Among the bacterial isolates, lowest radial growth (4.6 cm) and highest per cent inhibition (48.89%) of S. rolfsii were recorded with Bacillus subtilis PDBC isolate. But the highest radial growth (7.6 cm) and lowest per cent inhibition (15.56%) was recorded with P. fluorescens SPA1 isolate.

Manejo da podridão-de-Sclerotium em pimentão em um argisolo no Amazonas / Southern blight management of bell pepper in an argissol in the Amazonas State

Southern blight is a common disease in plants belonging to the Solanaceae family in the Amazon. To compare southern blight management strategies for bell pepper (Capsicum annuum, L. Solanaceae) a field experiment was conducted in a split plot design with main plots arranged in randomized blocks, with six replicates for each treatment, in a red-yellow Argisol (Ultisol) artificially infested with Sclerotium rolfsii. The main factor was soil cover (sawdust mulch or bare soil) The secondary factors were the incorporation to the soil: 1) compost (3 L by planting hole), 2) rice colonized by Trichoderma harzianum (90 g by planting hole, with ≈ 1.4 x 10(9) conidia g-1) and 3) compost and T. harzianum in the same proportion described previously; 4) control. All plants were fertilized with 1.5 L of compost by planting hole except those in the treatments with 3 L of compost by hole. The main plot had three rows with ten bell pepper plants (0.50 x 1.0 m) and the subplot, three rows with five plants. Southern blight incidence was accessed twice a week. The sawdust mulch increased the disease incidence significantly. In the mulched plots the disease intensity, expressed as the area under disease progress curve (AUDPC), increase 35.5% compared with bare soil. Trichoderma harzianum or the increase in the amount of compost (1.5 L to 3 L by planting hole) reduced the AUDPC by 38.1% and of 37.5%, respectively. Furthermore T. harzianum or the increase in the amount of compost, even with sawdust mulch added, reduced the AUDPC by 52.8% and in 55.1%, respectively, in comparison with mulch alone. These results suggested that the utilization of T. harzianum or the increase in the amount of compost by planting hole are viable strategies to southern blight management in bell pepper. The sawdust surface mulch is not recommended in an S. rolfsii infested area.

A podridão-de-Sclerotium é uma doença comum em plantas da família Solanaceae na Amazônia. Visando avaliar estratégias de manejo para esta doença em pimentão (Capsicum annuum, L. Solanaceae), foi conduzido experimento em campo em blocos casualizados com parcelas subdivididas e seis repetições, em Argissolo Vermelho-Amarelo artificialmente infestado com Sclerotium rolfsii. O tratamento principal foi a cobertura do solo (cobertura do solo com serragem ou solo nu). Os tratamentos secundários consistiram na adição ao solo de: 1) composto vegetal (3 L por cova), 2) arroz colonizado com Trichoderma harzianum (90 g por cova contendo ≈ 1,4 x 10(9) conídios g-1), 3) composto vegetal e T. harzianum nas mesmas proporções descritas anteriormente e 4) testemunha. Todas as plantas receberam apenas adubação orgânica com composto vegetal na proporção de 1,5 L por cova, exceto as dos tratamentos com 3 L de composto por cova. A parcela principal foi constituída de três fileiras com dez plantas de pimentão (0,50 x 1,0 m) e cada subparcela continha três fileiras com cinco plantas. A incidência da podridão-de-Sclerotium foi avaliada duas vezes por semana. A cobertura morta favoreceu significativamente a ocorrência da doença. Nas parcelas com esse tratamento o aumento da intensidade da doença, expressa em área abaixo da curva de progresso da doença (AACPD), foi 35,5% maior, em comparação com as parcelas sem cobertura morta. A aplicação de T. harzianum ou o incremento na quantidade de composto (de 1,5 para 3 L por cova) reduziu a AACPD em 38,1% e 37,5%, respectivamente. A aplicação de T. harzianum ou o incremento na quantidade de composto, mesmo nos tratamentos com cobertura morta, reduziu significativamente a AACPD em 52,8% e em 55,1%, respectivamente, em comparação com o tratamento apenas com cobertura morta. Esses resultados sugerem que a utilização de T. harzianum e o aumento na quantidade de composto por cova são estratégias eficientes de manejo da podridão-de-Sclerotium em...

Essential oil chemical composition and antifungal effects on Sclerotium cepivorum of Thymus capitatus wild populations from Calabria, southern Italy

The paper reports the qualitative and quantitative composition and its antifungal activities of Thymus capitatus (L.) Hoffmanns. & Link, Lamiaceae, essential oils isolated by hydrodistillation from the aerial parts of plants collected in Calabria, Southern Italy. The essential oils of 22 samples were analysed by GC-Flame ionization detection and GC/MS. A total of sixty five compounds were identified. Phenols were present in highest percentage (average: 79,03%). Carvacrol was the main component (81,52%-78,40%) in all samples, confirming that T. capitatus is a carvacrol chemotype, according to literature data for this species. This essential oil was also characterized by high level of biogenetic precursor of the phenols: p-cimene (4,98%), γ-terpinene (3,13%) and by β-cariophyllene, were the most abundant sesquiterpene hydrocarbons. Antifungal activity against Sclerotium cepivorum Berk., a soil born fungus, was tested. At the concentration of 250 ppm there was no development of fungal mycelium. To our knowledge, studies have never been conducted on Calabria wild populations of T. capitatus essential oil nor were conducted studies on parasitic fungi of specific interest for crops such as Sclerotium cepivorum.

Evaluación in vitro de aislamientos de Trichoderma harzianum para el control de Rhizoctonia solani, Sclerotium rolfsii y Fusarium oxysporum en plantas de tomate / In vitro evaluation of Trichoderma harzianum for control of Rhizoctonia solani, Sclerotium rolfsii, and Fusarium oxysporum in tomato plants

En este estudio se determinó la capacidad antagónica de aislamientos de T. harzianum para el control de Rhizoctonia solani, Sclerotium rolfsii y Fusarium oxysporum en raíces de plantas de tomate. Se obtuvieron 6 aislamientos de T. harzianum de 6 municipios del estado Trujillo, empleando la técnica de siembra directa de raíces en agar agua acidificada. El antagonismo se realizó en cultivos duales utilizando agar papa dextrosa, incubados a 25 ºC, bajo un diseño al azar, con 18 tratamientos conformados por cada aislamiento de T. harzianum y cada patógeno, 3 tratamientos testigos correspondientes a cada patógeno y 3 repeticiones por tratamiento, evaluándose el modo de acción e inhibición del crecimiento radial al tercer día. Todos los aislamientos de T. harzianum mostraron un rápido crecimiento sin diferencias significativas entre ellos (p>0,05), aún cuando se observó que el T121 fue más eficaz como controlador. Al comparar el crecimiento de los aislamientos de T. harzianum con el de los hongos patógenos, se obtuvieron diferencias significativas (p<0,05). Cuatro aislamientos de T. harzianum presentaron acción micoparasítica y dos de tipo antibiosis, mecanismos característicos de estas especies de biocontroladores. Todos los aislamientos de T. harzianum estudiados pueden ser utilizados para el control de patógenos de tomate.

This study determined the antagonistic capacity of T. harzianum isolates for control of Rhizoctonia solani, Sclerotium rolfsii, and Fusarium oxysporum in the roots of tomato plants. Six T. harzianum isolates were obtained from 6 municipalities of Trujillo State, using the direct inoculation of roots in acidified water agar technique. The antagonism was carried out in dual cultures using potato dextrose agar, incubated at 25 ºC, under a random design, with 18 treatments conformed for each T. harzianum isolate and each pathogen, 3 control treatments corresponding to each pathogen, and 3 repetitions per treatment, evaluating the mode of action and inhibition of radial growth at the third day. All the T. harzianum isolates showed rapid growth without significant differences among them (p>0.05), even though it was observed that T121 was more efficient as controller. When comparing the growth of the T. harzianum isolates with that of the pathogenic fungi, there were significant differences (p<0.05). Four T. harzianum isolates showed mycoparasitic action, and two antibiosis type action, which are characteristic mechanisms of these bio-controlling species. All the T. harzianum isolates studied can be used for the control of tomato pathogens.

First Report of Sclerotium Rot on Cymbidium Orchids Caused by Sclerotium rolfsii in Korea

Sclerotium rot was found on Cymbidium orchids at Seosan-si, Chungcheongnam-do, Korea, in July, 2010. Symptoms occurred on low leaves, which turned yellowish, after which the entire plant wilted. Severely infected plants were blighted and eventually died. White mycelial mats and sclerotia appeared on pseudobulbs. Based on the mycological characteristics and pathogenicity, the causal fungus was identified as Sclerotium rolfsii. This is the first report of new Sclerotium rot on Cymbidium spp. caused by S. rolfsii in Korea.