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1.
Braz. j. microbiol ; 46(4): 1093-1101, Oct.-Dec. 2015. graf
Article in English | LILACS | ID: lil-769640

ABSTRACT

Abstract Sampling of agricultural soils from the Mexican northeastern region was performed to detect Trichoderma spp., genetically characterize it, and assess its potential use as a biologic control agent against Macrophomina phaseolina. M. phaseolina is a phytopathogen that attacks over 500 species of cultivated plants and causes heavy losses in the regional sorghum crop. Sampling was performed immediately after sorghum or corn harvest in an area that was approximately 170 km from the Mexico-USA border. Sixteen isolates were obtained in total. Using colony morphology and sequencing the internal transcribed spacers (ITS) 1 and 4 of 18S rDNA, 14 strains were identified as Trichoderma harzianum, T. koningiopsis and T. virens. Subsequently, their antagonistic activity against M. phaseolina was evaluated in vitro, and 11 isolates showed antagonism by competition and stopped M. phaseolina growth. In 4 of these isolates, the antibiosis phenomenon was observed through the formation of an intermediate band without growth between colonies. One strain, HTE808, was identified as Trichoderma koningiopsis and grew rapidly; when it came into contact with the M. phaseolina colony, it continued to grow and sporulated until it covered the entire petri dish. Microscopic examination confirmed that it has a high level of hyperparasitism and is thus considered to have high potential for use in the control of this phytopathogen.


Subject(s)
Antibiosis/microbiology , Antibiosis/physiology , Antibiosis/prevention & control , Ascomycota/microbiology , Ascomycota/physiology , Ascomycota/prevention & control , Mexico/microbiology , Mexico/physiology , Mexico/prevention & control , Plant Diseases/microbiology , Plant Diseases/physiology , Plant Diseases/prevention & control , Sorghum/microbiology , Sorghum/physiology , Sorghum/prevention & control , Trichoderma/microbiology , Trichoderma/physiology , Trichoderma/prevention & control , Zea mays/microbiology , Zea mays/physiology , Zea mays/prevention & control
2.
Braz. j. microbiol ; 46(4): 1077-1085, Oct.-Dec. 2015. tab, graf
Article in English | LILACS | ID: lil-769659

ABSTRACT

Abstract The entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae, Lecanicillium lecanii and Isaria fumosorosea were tested for their efficacy in managing the exotic spiraling whitefly Aleurodicus dispersus (Hemiptera, Aleyrodidae) on cassava (Manihot esculenta) during 2 seasons (2011-2012 and 2012-2013). The fungi I. fumosorosea and L. lecanii exhibited promising levels of control (> 70% mortality of the A. dispersus population). The percent mortality increased over time in both seasons. Application of I. fumosorosea was highly pathogenic to A. dispersus in both seasons compared to the other entomopathogenic fungi. Analysis of the percent mortality in both seasons revealed differences in efficacy between 3 and 15 days after treatment. The season also influenced the effects of the fungi on the A. dispersus population. Thus, entomopathogenic fungi have the potential to manage A. dispersus infestation of cassava.


Subject(s)
Animals/microbiology , Animals/parasitology , Animals/physiology , Animals/prevention & control , Hemiptera/microbiology , Hemiptera/parasitology , Hemiptera/physiology , Hemiptera/prevention & control , Hypocreales/microbiology , Hypocreales/parasitology , Hypocreales/physiology , Hypocreales/prevention & control , Manihot/microbiology , Manihot/parasitology , Manihot/physiology , Manihot/prevention & control , Pest Control, Biological/microbiology , Pest Control, Biological/parasitology , Pest Control, Biological/physiology , Pest Control, Biological/prevention & control , Plant Diseases/microbiology , Plant Diseases/parasitology , Plant Diseases/physiology , Plant Diseases/prevention & control
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