RESUMO

Gray mold (Botrytis cinerea), late blight (Phytophthora infestans), powdery mildew (Leveillula taurica), pith necrosis (Pseudomonas corrugata), and bacterial canker (Clavibacter michiganensis) are major diseases that affect tomato (Solanum lycopersicum L.) in greenhouse production in Mexico. Management of these diseases depends heavily on chemical control, with up to 24 fungicide applications required in a single season to control fungal diseases, thus ensuring a harvestable crop. While disease chemical control is a mainstay practice in the region, its frequent use increases the production costs, likelihood of pathogen-resistance development, and negative environmental impact. Due to this, there is a need for alternative practices that minimize such effects and increase profits for tomato growers. The aim of this study is to evaluate the effect of biorational products in the control of these diseases in greenhouse production. Four different treatments, including soil application of Bacillus spp. or B. subtilis and foliar application of Reynoutria sachalinensis, Melaleuca alternifolia, harpin αß proteins, or bee honey were evaluated and compared to a conventional foliar management program (control) in a commercial production greenhouse in Central Mexico in 2016 and 2017. Disease incidence was measured at periodic intervals for six months and used to calculate the area under the disease progress curve (AUDPC). Overall, the analysis of the AUDPC showed that all treatments were more effective than the conventional program in controlling most of the examined diseases. The tested products were effective in reducing the intensity of powdery mildew and gray mold, but not that of bacterial canker, late blight, and pith necrosis. Application of these products constitutes a disease management alternative that represents cost-saving to tomato growers of about 2500 U.S. dollars per production cycle ha-1, in addition to having less negative impact on the environment. The products tested in this study have the potential to be incorporated in an integrated program for management of the examined diseases in tomato in this region.

RESUMO

Asian soybean rust is an aggressive disease and chemical control must be handled assertively to minimize productivity damage. The objective was to evaluate systemic fungicides and multisite mancozeb, combined or not, and the effects on disease control and soybean yield, cv. 'BMX Lança'. The work was conducted in the field in the 2016/17 and 2017/18 crops, in a randomized complete block design, with four replications. The following treatments were evaluated: T+P) trifloxystrobin + prothioconazole; A+B) azoxystrobin + benzovindiflupyr; T+P+MB) trifloxystrobin + prothioconazole + mancozeb; A+B+MB) azoxystrobin + benzovindiflupyr + mancozeb; MB) mancozeb; and Control (without fungicide application). After the occurrence of the first symptoms of the disease, the severity (%) was evaluated in five trifolia per plot, every seven days, making it possible to calculate the area under the disease progress curve (AUDPC). The yield components and productivity (kg ha-1) were also evaluated. In both crops, the combination of systemic fungicides and mancozeb reduced the severity (%) and progress of Asian rust, reaching a control above 81%. Treatment with trifloxystrobin + prothioconazole + mancozeb (T+P+MB) obtained the highest percentages of control (94.5% -2016/17,and 93.7% -2017/18) of Asian rust, and provided, in the 2016/17 crop, productivity at 15 sc ha-1, in relation to the fungicide applied alone (T+P). The combination of systemic fungicides and mancozeb, as proposed in this work, reduces the severity and progress of Asian rust and ensures the maintenance of the productive potential of the soybean.

A ferrugem asiática da soja é uma doença agressiva e o controle químico deve ser manejado assertivamente, para minimizar danos sobre a produtividade. Objetivou-se avaliar fungicidas sistêmicos e o multissítio mancozeb, combinados ou não, e os efeitos sobre o controle da doença e a produtividade da soja, cv. ‘BMX Lança’. O trabalho foi conduzido à campo nas safras 2016/17 e 2017/18, em delineamento de blocos ao acaso, com quatro repetições. Foram avaliados os tratamentos: T+P) trifloxistrobina + protioconazol; A+B) azoxistrobina + benzovindiflupyr; T+P+MB) trifloxistrobina + protioconazol + mancozeb; A+B+MB) azoxistrobina + benzovindiflupyr + mancozebe; MB) mancozeb; e Testemunha (sem aplicação de fungicidas). Após o surgimento dos primeiros sintomas da doença, a severidade (%) foi avaliada em cinco trifólios por parcela, a cada sete dias, possibilitando o cálculo da área abaixo da curva de progresso da doença (AACPD). Avaliou-se também os componentes de rendimento e a produtividade (kg ha-1). Em ambas as safras, a combinação entre fungicidas sistêmicos e o mancozeb reduziu a severidade (%) e o progresso de ferrugem asiática, atingindo um controle acima de 81%. O tratamento com trifloxistrobina + protioconazol + mancozeb (T+P+MB) obteve os maiores percentuais de controle (94,5% -2016/17; e 93,7% -2017/18) da ferrugem asiática, e proporcionou, na safra 2016/17, produtividade superior em 15 sc ha-1, em relação ao fungicida aplicado isoladamente (T+P). A combinação entre fungicidas sistêmicos e mancozeb, conforme proposto nesse trabalho, reduz a severidade e o progresso da ferrugem asiática e assegura a manutenção do potencial produtivo da soja.

Assuntos

RESUMO

Asian soybean rust is an aggressive disease and chemical control must be handled assertively to minimize productivity damage. The objective was to evaluate systemic fungicides and multisite mancozeb, combined or not, and the effects on disease control and soybean yield, cv. 'BMX Lança'. The work was conducted in the field in the 2016/17 and 2017/18 crops, in a randomized complete block design, with four replications. The following treatments were evaluated: T+P) trifloxystrobin + prothioconazole; A+B) azoxystrobin + benzovindiflupyr; T+P+MB) trifloxystrobin + prothioconazole + mancozeb; A+B+MB) azoxystrobin + benzovindiflupyr + mancozeb; MB) mancozeb; and Control (without fungicide application). After the occurrence of the first symptoms of the disease, the severity (%) was evaluated in five trifolia per plot, every seven days, making it possible to calculate the area under the disease progress curve (AUDPC). The yield components and productivity (kg ha-1) were also evaluated. In both crops, the combination of systemic fungicides and mancozeb reduced the severity (%) and progress of Asian rust, reaching a control above 81%. Treatment with trifloxystrobin + prothioconazole + mancozeb (T+P+MB) obtained the highest percentages of control (94.5% -2016/17,and 93.7% -2017/18) of Asian rust, and provided, in the 2016/17 crop, productivity at 15 sc ha-1, in relation to the fungicide applied alone (T+P). The combination of systemic fungicides and mancozeb, as proposed in this work, reduces the severity and progress of Asian rust and ensures the maintenance of the productive potential of the soybean.(AU)

A ferrugem asiática da soja é uma doença agressiva e o controle químico deve ser manejado assertivamente, para minimizar danos sobre a produtividade. Objetivou-se avaliar fungicidas sistêmicos e o multissítio mancozeb, combinados ou não, e os efeitos sobre o controle da doença e a produtividade da soja, cv. ‘BMX Lança. O trabalho foi conduzido à campo nas safras 2016/17 e 2017/18, em delineamento de blocos ao acaso, com quatro repetições. Foram avaliados os tratamentos: T+P) trifloxistrobina + protioconazol; A+B) azoxistrobina + benzovindiflupyr; T+P+MB) trifloxistrobina + protioconazol + mancozeb; A+B+MB) azoxistrobina + benzovindiflupyr + mancozebe; MB) mancozeb; e Testemunha (sem aplicação de fungicidas). Após o surgimento dos primeiros sintomas da doença, a severidade (%) foi avaliada em cinco trifólios por parcela, a cada sete dias, possibilitando o cálculo da área abaixo da curva de progresso da doença (AACPD). Avaliou-se também os componentes de rendimento e a produtividade (kg ha-1). Em ambas as safras, a combinação entre fungicidas sistêmicos e o mancozeb reduziu a severidade (%) e o progresso de ferrugem asiática, atingindo um controle acima de 81%. O tratamento com trifloxistrobina + protioconazol + mancozeb (T+P+MB) obteve os maiores percentuais de controle (94,5% -2016/17; e 93,7% -2017/18) da ferrugem asiática, e proporcionou, na safra 2016/17, produtividade superior em 15 sc ha-1, em relação ao fungicida aplicado isoladamente (T+P). A combinação entre fungicidas sistêmicos e mancozeb, conforme proposto nesse trabalho, reduz a severidade e o progresso da ferrugem asiática e assegura a manutenção do potencial produtivo da soja.(AU)

Assuntos

RESUMO

Artificial neural networks (ANN) are computational models inspired by the neural systems of living beings capable of learning from examples and using them to solve problems such as non-linear prediction, and pattern recognition, in addition to several other applications. In this study, ANN were used to predict the value of the area under the disease progress curve (AUDPC) for the tomato late blight pathosystem. The AUDPC is widely used by epidemiologic studies of polycyclic diseases, especially those regarding quantitative resistance of genotypes. However, a series of six evaluations over time is necessary to obtain the final area value for this pathosystem. This study aimed to investigate the utilization of ANN to construct an AUDPC in the tomato late blight pathosystem, using a reduced number of severity evaluations. For this, four independent experiments were performed giving a total of 1836 plants infected with Phytophthora infestans pathogen. They were assessed every three days, comprised six opportunities and AUDPC calculations were performed by the conventional method. After the ANN were created it was possible to predict the AUDPC with correlations of 0.97 and 0.84 when compared to conventional methods, using 50 % and 67 % of the genotype evaluations, respectively. When using the ANN created in an experiment to predict the AUDPC of the other experiments the average correlation was 0.94, with two evaluations, 0.96, with three evaluations, between the predicted values of the ANN and they were observed in six evaluations. We present in this study a new paradigm for the use of AUDPC information in tomato experiments faced with P. infestans. This new proposed paradigm might be adapted to different pathosystems.(AU)

Assuntos

RESUMO

Artificial neural networks (ANN) are computational models inspired by the neural systems of living beings capable of learning from examples and using them to solve problems such as non-linear prediction, and pattern recognition, in addition to several other applications. In this study, ANN were used to predict the value of the area under the disease progress curve (AUDPC) for the tomato late blight pathosystem. The AUDPC is widely used by epidemiologic studies of polycyclic diseases, especially those regarding quantitative resistance of genotypes. However, a series of six evaluations over time is necessary to obtain the final area value for this pathosystem. This study aimed to investigate the utilization of ANN to construct an AUDPC in the tomato late blight pathosystem, using a reduced number of severity evaluations. For this, four independent experiments were performed giving a total of 1836 plants infected with Phytophthora infestans pathogen. They were assessed every three days, comprised six opportunities and AUDPC calculations were performed by the conventional method. After the ANN were created it was possible to predict the AUDPC with correlations of 0.97 and 0.84 when compared to conventional methods, using 50 % and 67 % of the genotype evaluations, respectively. When using the ANN created in an experiment to predict the AUDPC of the other experiments the average correlation was 0.94, with two evaluations, 0.96, with three evaluations, between the predicted values of the ANN and they were observed in six evaluations. We present in this study a new paradigm for the use of AUDPC information in tomato experiments faced with P. infestans. This new proposed paradigm might be adapted to different pathosystems.

Assuntos

RESUMO

Present study was aimed to screening the population of 25 wheat genotypes from Baluchistan region of Pakistan along with five commercial cultivars for leaf rust adult plant resistance (APR) through gene postulation using natural inoculation of Puccinia triticina Erikss local pathotype. Infection severity was recorded on scale in comparison with susceptible control "Morroco" cultivar. On the basis of phenotypic score, seven accessions and four varieties (Zardana-89, Sariab-92, Zarlashta-99 and Raskoh-05) with AUDPC values up to 20% were characterized as resistant genotypes. Coefficient of infection (CI) score ranged from 0-10 for some accessions and cultivars showing high level of adult plant resistance. Furthermore, bi-allelic STS marker csLV34 having close linkage with Lr34 (0.4cM). This marker amplified one gene specific allele of 150bp in 21 genotypes, including 19 accessions and two commercial varieties (Sariab-92 and Zarghoon-79) which confirmed presence of Lr34 gene conferring adult plant resistance against leaf rust. The rust pathogenicity scale varied for accessions from resistant to moderately susceptible. However, beside Lr34, phenotypic gene postulation, in combination with marker assisted selection for leaf rust resistance, has revealed presence of some other unknown resistance genes in local wheat germplasm which signified its use in wheat improvement programs both locally and abroad.

O presente estudo teve como objetivo a triagem da população de 25 genótipos de trigo do Baluchistão, região do Paquistão, juntamente com cinco cultivares comerciais para o estudo da resistência à ferrugem da folha em plantas adultas (leaf rust adult plant resistance, APR, em inglês) através da postulação gênica usando a inoculação natural do patótipo local da Puccinia triticina Erikks. A gravidade da infecção foi registrada na escala em comparação ao cultivar de controle suscetível "Morroco". Com base na pontuação fenotípica, sete acessões e quatro variedades (Zardana-89, Sariab-92, Zarlashta-99 and Raskoh-05) com valores de AUDPC (area under the disease progress curve, em inglês) até 20% foram caracterizados como genótipos resistentes. A pontuação do coeficiente de infecção (CI) variou no intervalo de 0-10 para algumas acessões e cultivares evidenciando uma elevada resistência nas plantas adultas. Além disso, o STS marker para o csLV34 bi-alélico demonstrou uma ligação estreita com o Lr34 (0.4cM). Este marcador amplificou um alelo específico do gene do 150bp em 21 genótipos, incluindo 19 acessões e duas variedades comerciais (Sariab-92 and Zarghoon-79) o que confirmou a presença do gene Lr34 conferindo resistência às plantas adultas contra a ferrugem da folha. A escala de patogenicidade da ferrugem para as acessões de resistente a moderadamente suscetível. Contudo, além do Lr34, a postulação gênica fenotípica, em combinação com a seleção auxiliada (ou assistida) por marcadores para a resistência da ferrugem da folha, revelou a presença de outros genes resistentes desconhecidos no germoplasma do trigo local o que justifica a sua utilização em programas de melhoramento do trigo tanto a nível local quanto a nível internacional.

Assuntos

RESUMO

A ferrugem asiática, causada pelo fungo Phakopsora pachyrhizi Sydow & P. Sydow, é uma das principais doenças foliares da cultura da soja. Assim, objetivou-se com esse trabalho avaliar os efeitos das épocas de semeadura, populações de plantas e doses reduzidas de fungicidas na severidade da ferrugem asiática e seus reflexos no desenvolvimento e na produtividade da soja, cultivar MG/BR-46 (Conquista). Experimentos de campo foram conduzidos nos anos agrícolas de 2009/2010 e 2010/2011, sob infestação natural da ferrugem asiática. A partir do surgimento dos primeiros sintomas da ferrugem, iniciaram-se as pulverizações com os tratamentos fungicidas e as avaliações da severidade da doença. Para compreender a natureza e a extensão dos efeitos dos tratamentos, uma análise multivariada de fatores foi aplicada. Para a maioria das diferentes características agronômicas avaliadas e fatores, de um terço a dois terços da variabilidade pode ser explicada por mudanças na população de plantas ou por diferenças nos tratamentos com fungicidas; e o restante, pela variação na época de semeadura. Os tratamentos com fungicidas e a época de semeadura são determinantes na severidade da doença e na interferência desta na produtividade da cultura. Caracteres relacionados ao desenvolvimento vegetativo são mais dependentes das variações na população de plantas. As menores severidades da ferrugem asiática com os tratamentos fungicidas azoxystrobina + ciproconazol, refletiram em produtividades superiores. A população de plantas pode ser reduzida até 160 mil plantas ha-1 sem prejuízos no controle da doença e na produtividade da soja. No geral, semeaduras mais precoces proporcionaram aumento das características agronômicas relacionadas ao desenvolvimento vegetativo das plantas, apesar do controle menos eficiente da ferrugem.

Soybean rust caused by Phakopsora pachyrhizi Sydow & P. Sydow is one of the major diseases of the soybean crop. The aim of this study was to evaluate the effects of sowing dates, plant populations and reduced doses of fungicides on soybean rust severity and its effects on plant development and yield, cultivar MG/BR- 46 (Conquista). Field experiments were conducted in the 2009/2010 and 2010/2011 harvests, under natural rust infestation of soybean rust. As from the appearance of the first disease symptoms, also began the fungicide spraying and the disease severity assessments. To understand the nature and extent of the effects of different treatments, a multivariate analysis of factors was applied. For the majority of the agronomic characters and factors, one-third to two-thirds of their variability can be explained by changes in plant populations or by differences in the fungicide treatments, and the remainder, was explained by sowing date variations. The fungicide treatments and sowing dates are determinants in disease severity and its interference on crop productivity. The characters of plant growth are more dependent on plant population variations. Treatments with azoxystrobina + ciproconazol promoted smaller disease severities, reflecting in productivity increase. The plant populations can be reduced up to 160.000 plants ha-1 without losses in the disease control and the soybean yield. In general, the earliest sowings provided increase in the plant development, although the rust control was less efficient.

Assuntos

RESUMO

O fungo Phakopsora pachyrhizi Sydow & Sydow representa grande ameaça à sojicultura nas principais regiões produtoras do mundo, onde significativas perdas foram relatadas. Na quantificação de danos causados, muitas são as variáveis a serem estudadas, como área abaixo da curva de progresso da doença (AACPD), absorção de luz da área foliar sadia (HAA) e duração da área foliar sadia (HAD), além das curvas de progresso da doença. Neste trabalho, objetivou-se verificar a influência de diferentes herbicidas e fungicidas no progresso da doença, bem como suas implicações nas variáveis referentes à área foliar sadia e à produtividade da cultura. Os tratamentos testados em duas cultivares ('MG/BR46 Conquista' e 'BRS Valiosa RR') foram: 1. Testemunha; 2. Testemunha com herbicidas; 3. Herbicidas e pyraclostrobin (V4) + pyraclostrobin + epoxiconazole (R2 e R5.1); 4. Herbicidas e pyraclostrobin (V4) + epoxiconazole (R2 e R5.1); e 5. Herbicidas (V4) + pyraclostrobin + epoxiconazole (R2 e R5.1). Os herbicidas utilizados em 'MG/BR-46 Conquista' foram sethoxydim, bentazon e chlorimuron-ethyl, sendo utilizado glyphosate na 'BRS Valiosa RR'. O modelo logístico foi o que melhor se adequou à severidade média das avaliações e à curva de progresso da doença. Para o terço inferior, posição do dossel mais propícia à doença, o modelo logístico com taxa variável foi o que mais se ajustou aos dados. A pulverização de pyraclostrobin + epoxiconazole reduziu a taxa de desenvolvimento de P. pachyrhizi em relação à epoxiconazole. A utilização da mistura influenciou as variáveis AACPD, HAA e HAD, sendo estas consideradas apropriadas para a quantificação dos danos provocados pela ferrugem asiática. Na 'MG/BR-46 Conquista', a ação dos herbicidas afetaram temporariamente a área foliar, atingindo indiretamente as variáveis HAA e HAD.

Phakopsora pachyrhizi Sydow & Sydow is the worst threat for soybean crop in the most important growing regions around the world, where great losses were observed. Many variables are studied in the quantification of damage such as area under the disease progress curve (AUDPC), healthy leaf area absorption (HAA), healthy leaf area duration (HAD), in addition to disease progress curves. The present research aimed to evaluate the effect of several herbicides and fungicides on the progress of the disease and its implications for variables related to healthy leaf area and yield. The treatments were evaluated in two cultivars (MG/BR-46 Conquista e BRS Valiosa RR): 1. Control; 2. Control with herbicides; 3. Herbicides and pyraclostrobin (V4) + pyraclostrobin+ epoxiconazole (R2 and R5.1), 4. Herbicides and pyraclostrobin (V4) + epoxiconazole (R2 and R5.1). 5. Herbicides (V4) + pyraclostrobin + epoxiconazole (R2 and R5.1). The herbicides used in MG/BR-46 Conquista were sethoxydim, bentazon and chlorimuron-ethyl; in BRS Valiosa RR, glyphosate was used. The logistic was the model that best adapted to the mean severity ratings and the disease progress curve. At the bottom of canopy, position more favorable to this disease, the logistic model with variable rate was the model that better explain the data. The spraying of strobilurin's group associated with triazole (pyraclostrobin + epoxiconazole) reduced the rate of asian rust development, in relation to the group of ergosterol biosynthesis inhibitors fungicide (epoxiconazole). The pyraclostrobin + epoxiconazole influenced the variables AUDPC, HAA and HAD, and these can be considered suitable to quantify damage caused by this disease. In MG/BR-46 Conquista, the herbicides action affects temporarily the leaf area, affecting indirectly the HAA and HAD variables.

RESUMO

Phakopsora pachyrhizi Sydow & Sydow is the worst threat for soybean crop in the most important growing regions around the world, where great losses were observed. Many variables are studied in the quantification of damage such as area under the disease progress curve (AUDPC), healthy leaf area absorption (HAA), healthy leaf area duration (HAD), in addition to disease progress curves. The present research aimed to evaluate the effect of several herbicides and fungicides on the progress of the disease and its implications for variables related to healthy leaf area and yield. The treatments were evaluated in two cultivars (MG/BR-46 Conquista e BRS Valiosa RR): 1. Control; 2. Control with herbicides; 3. Herbicides and pyraclostrobin (V4) + pyraclostrobin+ epoxiconazole (R2 and R5.1), 4. Herbicides and pyraclostrobin (V4) + epoxiconazole (R2 and R5.1). 5. Herbicides (V4) + pyraclostrobin + epoxiconazole (R2 and R5.1). The herbicides used in MG/BR-46 Conquista were sethoxydim, bentazon and chlorimuron-ethyl; in BRS Valiosa RR, glyphosate was used. The logistic was the model that best adapted to the mean severity ratings and the disease progress curve. At the bottom of canopy, position more favorable to this disease, the logistic model with variable rate was the model that better explain the data. The spraying of strobilurin's group associated with triazole (pyraclostrobin + epoxiconazole) reduced the rate of asian rust development, in relation to the group of ergosterol biosynthesis inhibitors fungicide (epoxiconazole). The pyraclostrobin + epoxiconazole influenced the variables AUDPC, HAA and HAD, and these can be considered suitable to quantify damage caused by this disease. In MG/BR-46 Conquista, the herbicides action affects temporarily the leaf area, affecting indirectly the HAA and HAD variables.

O fungo Phakopsora pachyrhizi Sydow & Sydow representa grande ameaça à sojicultura nas principais regiões produtoras do mundo, onde significativas perdas foram relatadas. Na quantificação de danos causados, muitas são as variáveis a serem estudadas, como área abaixo da curva de progresso da doença (AACPD), absorção de luz da área foliar sadia (HAA) e duração da área foliar sadia (HAD), além das curvas de progresso da doença. Neste trabalho, objetivou-se verificar a influência de diferentes herbicidas e fungicidas no progresso da doença, bem como suas implicações nas variáveis referentes à área foliar sadia e à produtividade da cultura. Os tratamentos testados em duas cultivares ('MG/BR46 Conquista' e 'BRS Valiosa RR') foram: 1. Testemunha; 2. Testemunha com herbicidas; 3. Herbicidas e pyraclostrobin (V4) + pyraclostrobin + epoxiconazole (R2 e R5.1); 4. Herbicidas e pyraclostrobin (V4) + epoxiconazole (R2 e R5.1); e 5. Herbicidas (V4) + pyraclostrobin + epoxiconazole (R2 e R5.1). Os herbicidas utilizados em 'MG/BR-46 Conquista' foram sethoxydim, bentazon e chlorimuron-ethyl, sendo utilizado glyphosate na 'BRS Valiosa RR'. O modelo logístico foi o que melhor se adequou à severidade média das avaliações e à curva de progresso da doença. Para o terço inferior, posição do dossel mais propícia à doença, o modelo logístico com taxa variável foi o que mais se ajustou aos dados. A pulverização de pyraclostrobin + epoxiconazole reduziu a taxa de desenvolvimento de P. pachyrhizi em relação à epoxiconazole. A utilização da mistura influenciou as variáveis AACPD, HAA e HAD, sendo estas consideradas apropriadas para a quantificação dos danos provocados pela ferrugem asiática. Na 'MG/BR-46 Conquista', a ação dos herbicidas afetaram temporariamente a área foliar, atingindo indiretamente as variáveis HAA e HAD.

RESUMO

Phakopsora pachyrhizi Sydow & Sydow is the worst threat for soybean crop in the most important growing regions around the world, where great losses were observed. Many variables are studied in the quantification of damage such as area under the disease progress curve (AUDPC), healthy leaf area absorption (HAA), healthy leaf area duration (HAD), in addition to disease progress curves. The present research aimed to evaluate the effect of several herbicides and fungicides on the progress of the disease and its implications for variables related to healthy leaf area and yield. The treatments were evaluated in two cultivars (MG/BR-46 Conquista e BRS Valiosa RR): 1. Control; 2. Control with herbicides; 3. Herbicides and pyraclostrobin (V4) + pyraclostrobin+ epoxiconazole (R2 and R5.1), 4. Herbicides and pyraclostrobin (V4) + epoxiconazole (R2 and R5.1). 5. Herbicides (V4) + pyraclostrobin + epoxiconazole (R2 and R5.1). The herbicides used in MG/BR-46 Conquista were sethoxydim, bentazon and chlorimuron-ethyl; in BRS Valiosa RR, glyphosate was used. The logistic was the model that best adapted to the mean severity ratings and the disease progress curve. At the bottom of canopy, position more favorable to this disease, the logistic model with variable rate was the model that better explain the data. The spraying of strobilurin's group associated with triazole (pyraclostrobin + epoxiconazole) reduced the rate of asian rust development, in relation to the group of ergosterol biosynthesis inhibitors fungicide (epoxiconazole). The pyraclostrobin + epoxiconazole influenced the variables AUDPC, HAA and HAD, and these can be considered suitable to quantify damage caused by this disease. In MG/BR-46 Conquista, the herbicides action affects temporarily the leaf area, affecting indirectly the HAA and HAD variables.

O fungo Phakopsora pachyrhizi Sydow & Sydow representa grande ameaça à sojicultura nas principais regiões produtoras do mundo, onde significativas perdas foram relatadas. Na quantificação de danos causados, muitas são as variáveis a serem estudadas, como área abaixo da curva de progresso da doença (AACPD), absorção de luz da área foliar sadia (HAA) e duração da área foliar sadia (HAD), além das curvas de progresso da doença. Neste trabalho, objetivou-se verificar a influência de diferentes herbicidas e fungicidas no progresso da doença, bem como suas implicações nas variáveis referentes à área foliar sadia e à produtividade da cultura. Os tratamentos testados em duas cultivares ('MG/BR46 Conquista' e 'BRS Valiosa RR') foram: 1. Testemunha; 2. Testemunha com herbicidas; 3. Herbicidas e pyraclostrobin (V4) + pyraclostrobin + epoxiconazole (R2 e R5.1); 4. Herbicidas e pyraclostrobin (V4) + epoxiconazole (R2 e R5.1); e 5. Herbicidas (V4) + pyraclostrobin + epoxiconazole (R2 e R5.1). Os herbicidas utilizados em 'MG/BR-46 Conquista' foram sethoxydim, bentazon e chlorimuron-ethyl, sendo utilizado glyphosate na 'BRS Valiosa RR'. O modelo logístico foi o que melhor se adequou à severidade média das avaliações e à curva de progresso da doença. Para o terço inferior, posição do dossel mais propícia à doença, o modelo logístico com taxa variável foi o que mais se ajustou aos dados. A pulverização de pyraclostrobin + epoxiconazole reduziu a taxa de desenvolvimento de P. pachyrhizi em relação à epoxiconazole. A utilização da mistura influenciou as variáveis AACPD, HAA e HAD, sendo estas consideradas apropriadas para a quantificação dos danos provocados pela ferrugem asiática. Na 'MG/BR-46 Conquista', a ação dos herbicidas afetaram temporariamente a área foliar, atingindo indiretamente as variáveis HAA e HAD.

RESUMO

Phakopsora pachyrhizi Sydow & Sydow is the worst threat for soybean crop in the most important growing regions around the world, where great losses were observed. Many variables are studied in the quantification of damage such as area under the disease progress curve (AUDPC), healthy leaf area absorption (HAA), healthy leaf area duration (HAD), in addition to disease progress curves. The present research aimed to evaluate the effect of several herbicides and fungicides on the progress of the disease and its implications for variables related to healthy leaf area and yield. The treatments were evaluated in two cultivars (MG/BR-46 Conquista e BRS Valiosa RR): 1. Control; 2. Control with herbicides; 3. Herbicides and pyraclostrobin (V4) + pyraclostrobin+ epoxiconazole (R2 and R5.1), 4. Herbicides and pyraclostrobin (V4) + epoxiconazole (R2 and R5.1). 5. Herbicides (V4) + pyraclostrobin + epoxiconazole (R2 and R5.1). The herbicides used in MG/BR-46 Conquista were sethoxydim, bentazon and chlorimuron-ethyl; in BRS Valiosa RR, glyphosate was used. The logistic was the model that best adapted to the mean severity ratings and the disease progress curve. At the bottom of canopy, position more favorable to this disease, the logistic model with variable rate was the model that better explain the data. The spraying of strobilurin's group associated with triazole (pyraclostrobin + epoxiconazole) reduced the rate of asian rust development, in relation to the group of ergosterol biosynthesis inhibitors fungicide (epoxiconazole). The pyraclostrobin + epoxiconazole influenced the variables AUDPC, HAA and HAD, and these can be considered suitable to quantify damage caused by this disease. In MG/BR-46 Conquista, the herbicides action affects temporarily the leaf area, affecting indirectly the HAA and HAD variables.

O fungo Phakopsora pachyrhizi Sydow & Sydow representa grande ameaça à sojicultura nas principais regiões produtoras do mundo, onde significativas perdas foram relatadas. Na quantificação de danos causados, muitas são as variáveis a serem estudadas, como área abaixo da curva de progresso da doença (AACPD), absorção de luz da área foliar sadia (HAA) e duração da área foliar sadia (HAD), além das curvas de progresso da doença. Neste trabalho, objetivou-se verificar a influência de diferentes herbicidas e fungicidas no progresso da doença, bem como suas implicações nas variáveis referentes à área foliar sadia e à produtividade da cultura. Os tratamentos testados em duas cultivares ('MG/BR46 Conquista' e 'BRS Valiosa RR') foram: 1. Testemunha; 2. Testemunha com herbicidas; 3. Herbicidas e pyraclostrobin (V4) + pyraclostrobin + epoxiconazole (R2 e R5.1); 4. Herbicidas e pyraclostrobin (V4) + epoxiconazole (R2 e R5.1); e 5. Herbicidas (V4) + pyraclostrobin + epoxiconazole (R2 e R5.1). Os herbicidas utilizados em 'MG/BR-46 Conquista' foram sethoxydim, bentazon e chlorimuron-ethyl, sendo utilizado glyphosate na 'BRS Valiosa RR'. O modelo logístico foi o que melhor se adequou à severidade média das avaliações e à curva de progresso da doença. Para o terço inferior, posição do dossel mais propícia à doença, o modelo logístico com taxa variável foi o que mais se ajustou aos dados. A pulverização de pyraclostrobin + epoxiconazole reduziu a taxa de desenvolvimento de P. pachyrhizi em relação à epoxiconazole. A utilização da mistura influenciou as variáveis AACPD, HAA e HAD, sendo estas consideradas apropriadas para a quantificação dos danos provocados pela ferrugem asiática. Na 'MG/BR-46 Conquista', a ação dos herbicidas afetaram temporariamente a área foliar, atingindo indiretamente as variáveis HAA e HAD.

RESUMO

The aim of this work was to evaluate the efficiency of alternative products to control downy mildew in grapevine cv. Niágara Branca. The experiment was carried out at Epagri/Urussanga Experimental Station, in Santa Catarina State, Brazil, from September 2005 to February 2006. The following treatments were tested: phosphite K, phosphite PK, citric biomass, Bordeaux mixture, extract of the alga Ulva fasciata and control. The disease was evaluated by its area under disease progress curve in leafs (AUDPC), disease incidence in bunchs (ID) and productivity at harvest. The experimental design was completely randomized with four repetitions. Treatments were compared by the Duncans test (P5%). Bordeaux mixture reduced 59% of AUDPC in leafs and 45% of ID; phosphite K 0,2% and phosphite PK 0,2% reduced only AUDPC by 59% and 71%, compared with control, respectively. The algae U. fasciata extract 0,5% and citric biomass 0,25% didnt reduced disease development. Productivity was not affected by treatments.

Este trabalho teve como objetivo avaliar a eficiência de produtos alternativos para o controle do míldio da videira cv. Niágara Branca. O experimento foi conduzido em Urussanga, SC, no período de setembro de 2005 a fevereiro de 2006. Foram testados os seguintes tratamentos: fosfito K 0,2%, fosfito PK 0,2%, biomassa cítrica, calda bordalesa 0,5%, extrato da alga Ulva fasciata e testemunha. A sanidade foi avaliada pela área abaixo da curva de progresso da doença (AACPD) nas folhas, incidência da doença nos cachos (PCD) e produtividade no momento da colheita. O experimento foi conduzido em delineamento inteiramente casualizado e os tratamentos comparados pelo teste de Duncan. Destacaram-se a calda bordalesa 0,5% pela redução de 59% da AACPD na folha e 45% da PCD; fosfito K 0,2% e fosfito PK 0,2% somente na folha com 59% e 71% de redução da AACPD, comparados com a testemunha, respectivamente. Extrato de U. fasciata 0,5% e biomassa cítrica 0,25% não diferiram da testemunha em nenhuma das variáveis avaliadas. Os tratamentos não proporcionaram diferenças significativas na produtividade da cultura.

RESUMO

The aim of this work was to evaluate the efficiency of alternative products to control downy mildew in grapevine cv. Niágara Branca. The experiment was carried out at Epagri/Urussanga Experimental Station, in Santa Catarina State, Brazil, from September 2005 to February 2006. The following treatments were tested: phosphite K, phosphite PK, citric biomass, Bordeaux mixture, extract of the alga Ulva fasciata and control. The disease was evaluated by its area under disease progress curve in leafs (AUDPC), disease incidence in bunchs (ID) and productivity at harvest. The experimental design was completely randomized with four repetitions. Treatments were compared by the Duncans test (P5%). Bordeaux mixture reduced 59% of AUDPC in leafs and 45% of ID; phosphite K 0,2% and phosphite PK 0,2% reduced only AUDPC by 59% and 71%, compared with control, respectively. The algae U. fasciata extract 0,5% and citric biomass 0,25% didnt reduced disease development. Productivity was not affected by treatments.

Este trabalho teve como objetivo avaliar a eficiência de produtos alternativos para o controle do míldio da videira cv. Niágara Branca. O experimento foi conduzido em Urussanga, SC, no período de setembro de 2005 a fevereiro de 2006. Foram testados os seguintes tratamentos: fosfito K 0,2%, fosfito PK 0,2%, biomassa cítrica, calda bordalesa 0,5%, extrato da alga Ulva fasciata e testemunha. A sanidade foi avaliada pela área abaixo da curva de progresso da doença (AACPD) nas folhas, incidência da doença nos cachos (PCD) e produtividade no momento da colheita. O experimento foi conduzido em delineamento inteiramente casualizado e os tratamentos comparados pelo teste de Duncan. Destacaram-se a calda bordalesa 0,5% pela redução de 59% da AACPD na folha e 45% da PCD; fosfito K 0,2% e fosfito PK 0,2% somente na folha com 59% e 71% de redução da AACPD, comparados com a testemunha, respectivamente. Extrato de U. fasciata 0,5% e biomassa cítrica 0,25% não diferiram da testemunha em nenhuma das variáveis avaliadas. Os tratamentos não proporcionaram diferenças significativas na produtividade da cultura.