Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Aplicação foliar de fungicidas e incidência de grãos ardidos e fumonisinas totais em milho(Pesquisa Agropecuária Brasileira, 2016-05) Lanza, Fabrício Eustáquio; Zambolim, Laércio; Costa, Rodrigo Veras da; Silva, Dagma Dionísia da; Queiroz, Valéria Aparecida Vieira; Parreira, Douglas Ferreira; Mendes, Simone Martins; Souza, André Gomes Coelho; Cota, Luciano VianaO objetivo deste trabalho foi avaliar a eficiência da aplicação foliar de fungicidas na redução da incidência de patógenos fúngicos, de grãos ardidos e de fumonisinas totais em grãos de milho (Zea mays). Foram conduzidos três ensaios: um no município de Luís Eduardo Magalhães, na Bahia, e dois em Sete Lagoas, em Minas Gerais, nas safras 2010/2011 e 2011/2012, com cultivo de diferentes híbridos comerciais. Os seguintes fungicidas foram aplicados zero, uma e duas vezes: picoxistrobina + ciproconazol, piraclostrobina + epoxiconazole, trifloxistrobina + tebuconazole, azoxistrobina + ciproconazol e tiofanato metílico. Em todos os ensaios, foram realizados a quantificação da incidência de grãos ardidos, o teste de patologia de sementes e a quantificação dos teores de fumonisinas totais. Não foi observada diferença significativa para os fatores fungicida e número de aplicações, exceto para rendimento de grãos, em todos os ensaios. Esses resultados são indicativos da ineficiência da aplicação de fungicidas na redução da incidência de patógenos fúngicos, de grãos ardidos e dos teores de fumonisinas totais em grãos de milho.Item Resistance of Botrytis cinerea to fungicides controlling gray mold on strawberry in Brazil(Bragantia, 2017-04) Zambolim, Laércio; Lopes, Ueder Pedro; Capobiango, Nayara Pereira; Gracia, Nicolas Arturo Osorio; Freitas-Lopes, Rejane LivramentoThe aim of this study was to evaluate the resistance of Botrytis cinerea to the fungicides currently used for its control in Brazil. Isolates of the fungus were collected from different strawberry-producing fields in the states of Espírito Santo, Minas Gerais, and São Paulo, Brazil. First, a total of 183 isolates were identified at the species level using specific primers for the glyceraldehyde-3-phosphate dehydrogenase (G3PDH) gene. The isolates were grown on potato dextrose agar (PDA) containing the fungicides procymidone, iprodione, and thiophanate-methyl in different concentrations: 0.0 (control), 0.1; 1.0; 10.0; 100.0 and 1,000.0 μg∙mL−1. The percentage of mycelial growth inhibition was used to determine the effective concentration of the fungicide that was able to inhibit colony growth by 50% (EC50). Approximately 25.7% of the isolates were resistant to iprodione, 53.0% were resistant to procymidone, and 93.0% were resistant to thiophanate-methyl. Moreover, crossresistance and multiple resistance were verified, with 19.7% of the isolates showing resistance to 3 fungicides simultaneously. This finding explains the ineffectiveness of fungicides application to control gray mold in strawberry fields in Brazil and highlights the need for new strategies to manage this disease in the culture.Item DMI and QoI fungicides for the control of coffee leaf rust(Australasian Plant Pathology, 2015-09) Zambolim, Laércio; Lopes, Uilton do Nascimento; Lopes, Ueder Pedro; Honorato Jr., Jaime; Duarte, Henrique da Silva SilveiraThis study investigated the ability of different triazole and strobilurin fungicides either alone or combination when applied to the leaves and triazole to the soil for control of Coffee Leaf Rust (CLR). The experiments were performed in a greenhouse using three month-old coffee seedlings, and in the field with five years old plants using the susceptible variety ‘Catuai vermelho’, at elevation of 750 m, from 2010 to 2012, in Viçosa, Minas Gerais State, Brazil. The effects of triazole (triadimenol, cyproconazole and epoxiconazole) and strobilurin (azoxystrobin, trifloxystrobin, pyraclostrobin) was first studied in a greenhouse to evaluate the translaminar effect on CLR control. Based on the results obtained in the greenhouse, a field experiment was performed to evaluate the effect of triazole applied to the soil and triazole + strobilurin sprayed on CLR control and the effect on coffee berry yield of the plants. The different fungicides applied in the greenhouse reduced CLR severity by 8.9 % (trifloxystrobin), 79.4 % (azoxystrobin), 82.0 % (triadimenol), 93.2 % (cyproconazole), 96.6 % (epoxiconazole) and 98.5 % (pyraclostrobin) compared to that in the control plants. In the field experiment triazole + strobilurin fungicides provided effective CLR control. The co-application of epoxiconazole and pyraclostrobin or azoxystrobin sprayed twice resulted in the most effective CLR control and maintained the highest coffee berry yield. The incidence of CLR was 83.5, 54.0 and 78.5 % for the control treatments, whereas the incidence did not exceeded 24.4, 37.0 and 39.0 % on the sprayed plants. The average coffee berry yield increased by 33.9 % (lowest value) when applying triadimenol to the soil in November followed by cyproconazole + trifloxystrobin sprayed in December and February, and increased by 99.1 % (highest value) in the treatment with epoxiconazol + pyraclostrobin sprayed in December and March compared with plants that did not receive any fungicide application. The control treatment and that of triadimenol applied to the soil in November followed by cyproconazole + trifloxystrobin sprayed in December and February yielded less than 1800 (1320 to 1800) kg/ha of processed coffee, whereas the other treatments more than 2100 (2142 to 2676) kg/ha. Treatments with cyproconazole applied to the soil in November followed by cyproconazole + azoxystrobin sprayed on the leaves in December and February, epoxiconazol + pyraclostrobin sprayed on the leaves in December and March, and cyproconazole + azoxystrobin sprayed on leaves in December, February and April yielded more than 2340 (2340 to 2676) kg/ha of processed coffee. This is the first report indicating that a triazole fungicide applied to the soil and triazole + strobilurin fungicide sprayed on the leaves, efficiently controlled CLR and significantly increased coffee berry yield for three seasons.Item Biological control by Clonostachys rosea as a key component in the integrated management of strawberry gray mold(Biological Control, 2009-05-06) Cota, L. V.; Maffia, L. A.; Mizubuti, E. S. G.; Macedo, P. E. F.Gray mold, caused by Botrytis cinerea, is an important strawberry disease. As gray mold control is difficult, there is a need to evaluate integrated methods to successfully manage the disease. The efficiency of integrating Clonostachys rosea sprays, fungicide sprays, and crop debris removal to manage gray mold was evaluated in field experiments conducted in 2006 and 2007. Leaf colonization by C. rosea (LAC), average number of B. cinerea conidiophores (ANC), gray mold incidence in both flowers (Iflower) and fruits (Ifruit), and yield were evaluated weekly. In both years, LAC was higher in the treatments with no fungicide. When compared to the check, ANC, Iflower and Ifruit were most reduced in treatments that included C. rosea sprays. Maximal reductions were achieved with the combination of C. rosea sprays, fungicide sprays and debris removal (96.62%, 86.54% and 65.33% reductions of ANC, Iflower and Ifruit, respectively). Otherwise, maximal yield (103.14% increase as compared to the check) was achieved with the combination of the three treatments. With just C. rosea sprays, ANC, Iflower and Ifruit were reduced by 92.01%, 68.48% and 65.33%, respectively, whereas yield was increased by 75.15%. Considering the individual effects, application of C. rosea was the most efficient treatment. Chemical control was effective only in plots without debris removal. Elimination of crop debris was the least effective method in reducing gray mold incidence in both flowers and fruits. The integrated control approach enhanced the efficacy of the individual methods of gray mold control and provided high strawberry yield. An important component of this integrated approach it the biological control with C. rosea.