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)

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)

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

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 -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%). (AU)

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...

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.(AU)

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...(AU)

Isolation and fusion of protoplasts from the phytopathogenic fungus Sclerotium rolfsii (Sacc.)

Sclerotium rolfsii (Sacc.) is a serious plant pathogenic fungus and lacks perfect (basidial) stage in production. Protoplast fusion technology was employed to reconstruct fusants from this fungus. Two strains designated as A and R were used. Maximum protoplast yields of 3.8x10(5) /g mycelia and 2.8x10(5) /g mycelia were formed in strains A and R respectively. Osmotic stabilizer sucrose 1M gave maximum yield. Lysing enzyme at the rate of 15mg/ml was found best for yield. Fusion of protoplasts from strains A and R was carried out in fusion media containing PEG 4000 30% (w/v) with 0.2mM CaCl2. Four fusants F1, F2, F3 and F4 were recovered. Morphological, physiological and pathogenic characters of fusants were compared with parent strains on carrots, beans and tomato.

Secondary metabolites from Diplodia maydis and Sclerotium rolfsii with antibiotic activity

Ethyl acetate extracts of the phytopathogenic fungi Diplodia maydis and Sclerotium rolfsii presented antibacterial activity against multidrug resistant bacteria isolated from patients in the University Hospital (HUOP-Unioeste, Brazil).

Extratos de acetato de etila obtidos dos fungos fitopatogênicos Diplodia maydis e Sclerotium rolfsii mostraram atividade bactericida contra bactérias multi droga resistentes isoladas de pacientes de Hospital Brasileiro.

Fungitoxicty of Bidens pilosa, Thymus vulgaris, Lippia alba and Rosmarinus officinalis in the in vitro development of phytophatogens fungi / Fungitoxidade de Bidens pilosa, Thymus vulgaris, Lippia alba e Rosmarinus officinalis no desenvolvimento in vitro de fungos fitopatogênicos

The fungitoxicity of aqueous crude extracts (ACE) of Bidens pilosa, Thymus vulgaris, Lippia alba and Rosmarinus officinalis was evaluated in vitro on development of Alternaria alternata, Colletotrichum graminicola, Rhizoctonia solani and Sclerotium rolfsii. The active ACE were incorporated to Potato- Dextrose-Agar (PDA) alone or in mixture, at 0%, 1%, 5%, 10%, 15%, 25% and 50% concentrations. Measurement in fungal colonies was taken daily until the control treatment covered 2/3 of the culture media. The mixtures of T. vulgaris with B. pilosa did not have positive effect because the ACE of B. pilosa did not reduce the fungal growth of R. solani and in mixture inhibited the effect ACE of T. vulgaris. However, the mixture of ACEs of R. officinalis and L. alba produced better results than isolated ACEs, with 60% of growth inhibition of A. alternata. The ACE of T. vulgaris inhibited the growth of C. graminicola at 97%. The results show that ACEs have significative fungitoxicity in the evaluated phythopathogens.

Avaliou-se in vitro, a atividade fungitóxica dos extratos brutos aquosos (EBA) em diferentes concentrações isolados e em misturas de Bidens pilosa, Thymus vulgaris, Lippia alba e Rosmarinus officinalis no desenvolvimento dos fungos Alternaria alternata, Colletotrichum graminicola, Rhizoctonia solani e Sclerotium rolfsii. A avaliação foi realizada incorporando os extratos brutos aquosos (EBAs) ao meio BDA isolados e em mistura, nas concentrações 0%, 1%, 5%, 10%, 15%, 25% e 50%. Foram feitas medições diárias das colônias fúngicas até o momento em o tratamento controle cobriu 2/3 da superfície do meio de cultura. Verificou-se que a mistura de T. vulgaris com B. pilosa não teve efeito positivo, pois o EBA isolado de B. pilosa não reduziu o crescimento do fungo R. solani e em mistura reduziu o efeito do EBA de T. vulgaris. Porém, o EBAs de R. officinalis e L. alba em mistura levaram a melhores resultados, reduzindo em até 60% o crescimento de A. alternata, do que os EBAs isoladamente. O extrato isolado de T. vulgaris reduziu em até 97% o crescimento de C. graminicola. Os resultados demonstraram que os extratos brutos das plantas testadas tiveram ação fungitóxica significativa contra os quatro fitopatógenos.

Fungitoxicty of Bidens pilosa, Thymus vulgaris, Lippia alba and Rosmarinus officinalis in the in vitro development of phytophatogens fungi / Fungitoxidade de Bidens pilosa, Thymus vulgaris, Lippia alba e Rosmarinus officinalis no desenvolvimento in vitro de fungos fitopatogênicos

The fungitoxicity of aqueous crude extracts (ACE) of Bidens pilosa, Thymus vulgaris, Lippia alba and Rosmarinus officinalis was evaluated in vitro on development of Alternaria alternata, Colletotrichum graminicola, Rhizoctonia solani and Sclerotium rolfsii. The active ACE were incorporated to Potato- Dextrose-Agar (PDA) alone or in mixture, at 0%, 1%, 5%, 10%, 15%, 25% and 50% concentrations. Measurement in fungal colonies was taken daily until the control treatment covered 2/3 of the culture media. The mixtures of T. vulgaris with B. pilosa did not have positive effect because the ACE of B. pilosa did not reduce the fungal growth of R. solani and in mixture inhibited the effect ACE of T. vulgaris. However, the mixture of ACEs of R. officinalis and L. alba produced better results than isolated ACEs, with 60% of growth inhibition of A. alternata. The ACE of T. vulgaris inhibited the growth of C. graminicola at 97%. The results show that ACEs have significative fungitoxicity in the evaluated phythopathogens.

Avaliou-se in vitro, a atividade fungitóxica dos extratos brutos aquosos (EBA) em diferentes concentrações isolados e em misturas de Bidens pilosa, Thymus vulgaris, Lippia alba e Rosmarinus officinalis no desenvolvimento dos fungos Alternaria alternata, Colletotrichum graminicola, Rhizoctonia solani e Sclerotium rolfsii. A avaliação foi realizada incorporando os extratos brutos aquosos (EBAs) ao meio BDA isolados e em mistura, nas concentrações 0%, 1%, 5%, 10%, 15%, 25% e 50%. Foram feitas medições diárias das colônias fúngicas até o momento em o tratamento controle cobriu 2/3 da superfície do meio de cultura. Verificou-se que a mistura de T. vulgaris com B. pilosa não teve efeito positivo, pois o EBA isolado de B. pilosa não reduziu o crescimento do fungo R. solani e em mistura reduziu o efeito do EBA de T. vulgaris. Porém, o EBAs de R. officinalis e L. alba em mistura levaram a melhores resultados, reduzindo em até 60% o crescimento de A. alternata, do que os EBAs isoladamente. O extrato isolado de T. vulgaris reduziu em até 97% o crescimento de C. graminicola. Os resultados demonstraram que os extratos brutos das plantas testadas tiveram ação fungitóxica significativa contra os quatro fitopatógenos.