|Authors: ||Y. Zapata, A. Díaz, E. Grijalba, F. Rodríguez, Y. Elad, A.M. Cotes|
|Keywords: ||biocontrol, adherence, gray mold, diseases, postharvest|
The use of naturally occurring yeasts as biocontrol agents has attracted special interest because of their special attributes, nevertheless it has been recognized that the efficacy and consistent performance of such agents are affected by different factors.
In order to select a biocontrol agent for controlling gray mold, 23 indigenous phyllosphere yeasts were tested accordingly to different criteria, as biocontrol activity and adherence on rose petals, tolerance to UVB radiation and growth by micro-fermentation.
Results showed that all the evaluated yeasts significantly reduced gray mold development down from 17 to 64% and severity down from 2.5 to 30.0%, in comparison with the untreated control (100%). Yeast adherence ranged from 55 to 99%. Thirty percent of the tested yeasts showed less than 45% growth inhibition after UVB radiation exposure.
With respect to the maximum specific growth rate in micro-fermentation, yeast isolates showed values between 0.00525 and 0.6145. Accordingly to the above criteria and on their growth at standard conditions, five of the yeast isolates were selected and identified as Rhodotorula mucilaginosa (Co3), Rhodotorula glutinis (Si6), Debaryomyces hansenii (Si29) and Pichia onychis (F11 and F14). Taking into account that R. glutinis fulfilled other criteria for product development and commercialization, a liquid biopesticide formulation was developed.
However, further experiments should be conducted to determine the efficacy of this product under commercial rose production.
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