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1.
Braz. j. microbiol ; 40(2): 308-313, Apr.-June 2009. graf, tab, ilus
Article in English | LILACS | ID: lil-520235

ABSTRACT

Citrus black spot (CBS) is a plant disease of worldwide occurrence, affecting crops in Africa, Oceania, and South America. In Brazil, climate provides favorable conditions and CBS has spread to the Southeast and South regions. CBS is caused by the fungus Guignardia citricarpa (anamorph: Phyllosticta citricarpa) and its control is based on the use of fungicides, such as benzimidazoles. In South Africa, the disease was kept under control for 10 years with benomyl, until cases of resistance to high concentrations of this fungicide were reported from all citrus-producing areas. Azoxystrobin (a strobilurin) has been found effective in controlling phytopathogens, including CBS, in a wide range of economically important crops. The present study investigated in vitro the effects of the fungicides benomyl and azoxystrobin on 10 strains of G. citricarpa isolated from lesions in citrus plants from Brazil and South Africa. Benomyl at 0.5 µg/mL inhibited mycelial growth in all strains except PC3C, of African origin, which exhibited resistance to concentrations of up to 100.0 µg/mL. The spontaneous mutation frequency for resistance to benomyl was 1.25 ï 10-7. Azoxystrobin, even at high concentrations, did not inhibit mycelial growth in any of the strains, but significantly reduced sporulation rates, by as much as 100%, at a concentration of 5.0 µg/mL. Variations in sensitivity across strains, particularly to the strobilurin azoxystrobin, are possibly related to genetic variability in G. citricarpa isolates.


A Mancha Preta dos Citros (MPC) tem ocorrência mundial afetando a produção de citros na África, Oceania e América do Sul. No Brasil, onde o clima é favorável ao seu desenvolvimento, a doença está espalhada nas regiões Sul e Sudeste. O controle da MPC, causada pelo fungo Guignardia citricarpa (anamorfo: Phyllosticta citricarpa) é baseado na aplicação de fungicidas, como os benzimidazóis. Na África do Sul, após 10 anos de controle da doença com o fungicida benomil, os casos de resistência a altas concentrações deste fungicida atingiram todas as áreas produtoras. O fungicida estrolilurina chamado azoxistrobina tem se mostrado eficiente no controle dos fitopatógenos de uma grande variedade de culturas economicamente importantes, incluindo a MPC. Neste trabalho foram investigados os efeitos in vitro dos fungicidas benomil e azoxistrobina em 10 linhagens de G. citricarpa isoladas de lesões em plantas cítricas no Brasil e na África do Sul. Houve inibição do crescimento micelial a 0,5 µg/mL do fungicida benomil entre as linhagens testadas, com exceção de PC3C de origem sul-africana, que apresentou resistência até a concentração de 100,0 µg/mL de benomil. A freqüência de mutação espontânea para resistência ao benomil foi de 1,25 ï 10-7. A estrobilurina azoxistrobina, mesmo em altas concentrações, não inibiu o crescimento micelial dos isolados, entretanto reduziu significativamente a produção de esporos, chegando a 100% de inibição em concentrações de 5,0 µg/mL de azoxistrobina. A variação na sensibilidade das linhagens, principalmente com a estrobilurina azoxistrobina, possivelmente está relacionada com a variabilidade genética dos isolados de G. citricarpa.


Subject(s)
Benomyl/analysis , Citrus , Drug Resistance, Microbial , Plant Diseases/genetics , Fungicides, Industrial/analysis , Fungicides, Industrial/isolation & purification , In Vitro Techniques , Micelles , Genetic Variation , Methods , Plants , Methods , Virulence
2.
Journal of Shaheed Sadoughi University of Medical Sciences and Health Services. 2006; 13 (5): 65-70
in Persian | IMEMR | ID: emr-164326

ABSTRACT

Considering the importance and usefulness of fruits in people's daily diet as they play an important role in determining public health and also considering the significance of pesticide residues in foods and fruits, measurement of which has been repeatedly reiterated by WHO and FAO, this research was done. Irregular use of pesticides by farmers knowingly or unknowingly without observing its caress period has led to the contact of these pesticides with humans through foods and fruits and in the long run, they will surely cause chronic complications. In this study, after collecting cucumbers form 76 sample regions, we rinsed them carefully, sliced them thinly and mashed them up. Then, we extracted them three times with n butyl acetate. Later, we evaporated the solvent. At the end, we measured the residue by chromatographic gas [GC] and detector [ECD]. The results obtained were analyzed with the help of two-way ANOVA. It indicated that there is a correlation between the investigated regions and the residual amount [P>0.05]. Calculation of the mean ratings showed that the levels of these two pesticides are higher than the acceptable level in most of the regions. [0.01]


Subject(s)
Pesticides/adverse effects , Benomyl/analysis , Maneb/analysis , Zineb/analysis , Agriculture , Cucumis sativus
3.
Pesticidas ; 6: 43-54, jan.-dez. 1996. tab
Article in Portuguese | LILACS | ID: lil-187318

ABSTRACT

Mangas tratadas pós-colheita por imersao em Benomil (1OOO mg/Kg) foram armazenadas a 13 graus Celsius e 95 ñ 5 por cento UR, com e sem modificaçao da atmosfera por O, 10 e 20 dias. Os frutos foram descascados e nas polpas, os resíduos de Benomil foram quantificados por cromatografia líquida de alta eficiência com detector de ultravioleta-visível a 286 nm. Nao foram detectados resíduos de Benomil em nenhum dos tratamentos, dentro do limite de quantificaçao do método (O,3 mg/Kg). Os resultados obtidos sugerem que a modificaçao da atmosfera nao exerceu influência sobre os níveis residuais de Benomil nas polpas de mangas.


Subject(s)
Atmosphere , Benomyl/analysis , Fruit/chemistry , Fungicides, Industrial/analysis , Pesticide Residues/analysis , Chromatography, Liquid , Temperature
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