Effect of plant essential oils on the growth of Botrytis cinerea Pers.: Fr., Penicillium italicum Wehmer, and P. digitatum (Pers.) Sacc., diseases

Abstract

The current study was conducted to evaluate the effect of eight Palestinian indigenous plant essential oils (EOs) under in vitro and in vivo conditions against Botrytis cinerea Pers.: Fr., Penicillium italicum Wehmer, and Penicillium digitatum (Pers.) Sacc., three common postharvest pathogens of tomato and strawberry fruits. In vivo tests showed that thyme, sesame and sage EOs exhibited high antifungal activity against B. cinerea on strawberry and tomato fruits, compared with rosemary, mint and eucalyptus. In vitro agar, disk-diffusion tests showed that B. cinerea, P. digitatum and P. italicum mycelium growth was completely inhibited when treated with clove and sage EOs caused 50% inhibition of B. cinerea and P. italicum mycelium growth. Fruit decay and fruit quality index values measured in total soluble solids and fruit flesh firmness showed that EO coated strawberries had significantly less fruit decaying and ripping compared to control, while EO coated tomatoes showed no significant difference compared to control. EO constituents fall into different chemical classes, including sterols, caffeoylquinic acids, flavonoids, terpenoids, coumarins, and acetylenes. Chemical analysis of the EO preparations using gas chromatography-mass spectrometry determined that the main components in sesame oil were octadecenoic acid-(56%) and hexadecanoic acid (26%), while clove oil consisted of eugenol (53%). In the other EOs, the principal compounds were: menthol (44% in mint oil), eucalyptol (37% in sage oil), while bornanone (18% in rosemary oil) and γ-terpinene (21% in thyme oil) were present at lower concentrations. The EO of sage plants could potentially be a useful alternative to synthetic pesticides to control post-harvest diseases and prolong the shelf life of fruit products.