EFFECT OF ESSENTIAL OILS IN THE CONTROL OF THE Clavibacter michiganensis SUBESPECIE michiganensis IN TOMATO (Lycopersicum esculentum L.) PLANTS

Abstract

Plants produce compounds with antimicrobial properties that can be used to control diseases of horticultural products, for this reason, the aim of this study was to enlarge the knowledge on the effect of essential oils as an alternative for control for bacterial canker Clavibacter michiganensis subsp. michiganensis (Smith) (Cmm). Essential oil of Lippia palmeri was obtained by hydridestillation from plants collected in Sonora, Mexico. Essential oils of Origanum vulgare, Thymus vulgaris and Cinnamomum zeylanicum were obtained from commercial stores in Hermosillo, Sonora, Mexico. To evaluate the effect of the essential oils on the bacterium Cmm, direct applications in two concentrations (1:1 and 1:5 (v/v)) on tomato plants foliage were carried out. Then, plants were inoculated with 1x10-7 CFU/mL of the bacterium and observed for 12 days. The evaluated parameters were incidence and severity. The essential oils and chemical compounds of Origanum vulgare and Thymus vulgaris had effect against Clavibacter michiganensis subsp. michiganensis up to 9 days after application in a 1:1 (v/v) concentration and up to 12 days after application with the 1:5 (v/v) concentration. The essential oil of Lippia palmeri only had effect until six days after the application with both concentrations; that is to say, only these three types of essential oils had bactericidal properties, since with the essential oil of Cinnamomum zeylanicum the inhibition of Cmm was very limited, both in incidence as in severity.

Antibacterial Activity of Essential Oils and Trametes versicolor Extract against Clavibacter michiganensis subsp. michiganensis and Ralstonia solanacearum for Seed Treatment and Development of a Rapid In Vivo Assay

“…Oregano oil and cinnamon oil confirmed their antibacterial efficacy also by in vivo trials against Cmm, showing the possibility of using these EOs as tomato seeds treatments to prevent possible Cmm infection. These results are in agreement with with those of Flores et al [57] (2018), in which oregano, thyme, and cinnamon EOs were tested on tomato plants (but not on seeds) against Cmm, and the genus Origanum predominated in the inhibition of Cmm bacterium.…”

“…Besides the antibacterial activity and the phytotoxicity of the six EOs and Tve, in the present study, the in vivo effectiveness of two essential oils (oregano and cinnamon) in relation to seed treatments was evaluated. The choice of these oils was made on the basis of their known strong antibacterial activity and our previous experience with other pathogens [37,[57][58][59]. In particular, for Cmm, this antimicrobial efficacy is reported to be related to the high content of thymol and carvacrol [60] as well as cinnamaldehyde and cinnamic acid [61], even if significant variations that can occur in the chemical composition are likely to influence their antimicrobial features.…”