Verifying the biocontrol activity of novel film‐forming formulations of Candida sake CPA‐1: resilience in relation to environmental factors, rainfall episodes, and control of Botrytis cinerea on different hosts

BACKGROUND The efficacy of Candida sake CPA‐1 as a biocontrol agent against several diseases has been studied since it was isolated 20 years ago. However, it was only recently that two suitable and effective film‐forming formulations based on potato starch and maltodextrins were developed using the fluidized‐bed spray‐drying system. The present work aimed to confirm the capability of both novel formulations by testing their resilience on grapes at different temperatures (0, 22, and 30 °C), relative humidities (40% and 85%), and simulated rainfall levels. Another objective was to examine the control of Botrytis cinerea in different hosts. RESULTS The CPA‐1 cells from both dried formulations survived better than the liquid formulation on grapes stored at 0 and 22 °C regardless of the relative humidity. After simulated rainfall, potato starch formulation achieved significantly higher populations than maltodextrin formulation, although the highest reduction was −1.6 log N N0−1. A positive effect of cell establishment prior to the simulated rainfall was shown, and recovered cells from the potato starch formulation were significantly higher after 72 h of cell establishment. Finally, both formulations reduced the incidence and severity of B. cinerea on pears, apples, and tomatoes. CONCLUSION The potential of these novel film‐forming formulations of C. sake CPA‐1 was verified. The resilience of formulated C. sake was better than the commercialized liquid formulation, the adherence of the formulations to the grapes improved after an establishment period prior to rain exposure, and the control of B. cinerea was verified in a wider range of hosts. © 2019 Society of Chemical Industry

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