Assessing the Control of Postharvest Gray Mold Disease on Tomato Fruit Using Mixtures of Essential Oils and Their Respective Hydrolates.

Conny Brito,Katy Díaz,Sebastián Pino,Luis Espinoza,Henrik Hansen,Martín Faúndez,Andrés F Olea

doi:10.3390/plants10081719

Abstract

Gray mold disease, which is caused by Botrytis cinerea Pers ex. Fr., results in serious economic losses to Lycopersicum esculentum (tomato) crop productivity. In this study, we explored the possibility that mixtures of essential oils (EOs) and their respective hydrolates (HYSs) could be used to control this disease. Thus, EOs and HYSs were obtained from Origanum vulgare, Thymus vulgaris, Citrus limon, and Citrus sinensis by hydrodistillation. In vitro antifungal activities were evaluated, and EC50 values of 15.9 and 19.8 µg/mL were obtained for EOs of thyme and oregano, respectively. These activities are due mainly to volatile compounds, thymol and carvacrol. Results from in vivo assays show that although most tomatoes were infested five days after inoculation, the damage was considerably reduced by the application of an EO/HYS mixture of thyme. The disease incidence indexes of B. cinerea tomato rot, percentage and severity, measured four days after inoculation, were reduced by 70% and 76%, respectively, as compared with the inoculum control. These results suggest that a combination of HYSs and EOs enhances antifungal activity, and that optimization of relative concentrations, volumes, and the nature of the compounds, could design a formulation able to control B. cinerea inoculum on tomato fruits.

Highlights

Botrytis cinerea is a phytopathogenic fungi, known as “gray mold fungus”, that causes serious pre- and postharvest diseases in more than 200 different plant species, but considering other Botrytis spp., this number increases to 1500, including important food crops [1,2]
The latter are especially important in C. sinensis, where the lowest EC50 value was obtained for HYSs, several times lower than that measured for C. limon
Assessments of the in vivo preventive effects against B. cinerea were carried out using tomato fruit and essential oils (EOs)/HYS formulations

Summary

Introduction

Botrytis cinerea is a phytopathogenic fungi, known as “gray mold fungus”, that causes serious pre- and postharvest diseases in more than 200 different plant species, but considering other Botrytis spp., this number increases to 1500, including important food crops [1,2]. The negative public perception related to application of chemicals that could contaminate ground and natural water sources, has led this research to assess natural products with antifungal properties In this approach, numerous plants have been studied and plant metabolites with various antibiotic, anticancer, and antifungal activities have been extracted, isolated, and characterized [5,6,7,8,9,10]. Different series of synthetic analogs have been evaluated against B. cinerea and results have been used to establish structureactivity relationships [14,15,16] It has been known for many centuries that aromatic plants are a source of compounds possessing interesting properties for different applications. We have focused our attention on tomato (Lycopersicum esculentum) because it is one of the most important Solanaceous crops and gray mold affects leaves and fruits, and even during postharvest, B. cinerea induces severe fruit rot [38,39,40]

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Results

Conclusion