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Zapata J.,Colombian Corporation of Agricultural Research | Acosta C.,Colombian Corporation of Agricultural Research | Diaz A.,Colombian Corporation of Agricultural Research | Villamizar L.,Colombian Corporation of Agricultural Research | Cotes A.M.,Colombian Corporation of Agricultural Research
Acta Horticulturae | Year: 2011

Antagonistic microorganisms are affected by abiotic factors such as pH, temperature UVB radiation and A w when they are applied to the phyllosphere or undergo a formulation processes. However, the selection and design of a correct formulation and manufacturing process, could contribute to solve this problem. In this sense, three isolates of Pichia onychis, Lv027, Lv297 and Lv315 and three isolates of Rhodotorula glutinis, Lv316, Lv317 and Lv318 were characterized by determining the effect of pH, temperature, UVB radiation and A w on growth. The biocontrol activity against Botrytis cinerea in blackberry flowers and cells stability under storage conditions were measured when biomass was dried or suspended in an isotonic solution. A w and UVB radiation were the most limiting factors, when A w was reduced to 0.94 yeast growth reduction of 80% was observed. The growth of P. onychis strains was inhibited completely by UVB, while R. glutinis strains showed a growth inhibition between 16 and 42%. Temperatures between 5 and 37°C and pH between 3 and 9 did not affect yeasts growth. The highest stability was obtained for all yeasts, when cells were suspended in the isotonic solution. All evaluated yeasts reduced the incidence of B. cinerea between 11 and 81% in comparison with the control (90% incidence). However, isolate Lv316 of R. glutinis was selected to continue with a biopesticide development process as an aqueous formulation due to its high biocontrol activity (disease incidence of 18%) and tolerance to the UVB radiation. Source

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