Plant essential oils for controlling plant pathogenic fungi

Abstract

Phytopathogenic fungi consider the causal agents of plant diseases than any other group of plant pathogens, about 8000 species shown to cause many plant diseases on many crops. Some of the world's great famines and human suffering can be blamed on plant pathogenic fungi. The most important natural products derived from plants are the essential oils (EOs), as it has various biological properties and medicinal and nutritional uses. Excessive usage of synthetic chemical fungicides in the environment has increased risks to humans, flora, and fauna in recent years. Moreover, the development of resistance in species of pathogenic fungi due to the indiscriminate use of chemical fungicides for controlling plant pathogenic fungi. Most plant essential oils (EOs) are relatively nontoxic to laboratory animals and fish; they meet the criteria for "reduced risk" pesticides. Many EOs show a broad spectrum of activity against plant pathogenic fungi and have a long tradition application in the protection of stored products. Moreover, many EOs and their constituents are widely used as flavoring agents in foods and beverages. The special regulatory status, combined with the wide availability of EOs from the flavor and fragrance industries, has made it possible to fast-track commercialization of EO-based pesticides as green pesticides. Such green pesticides have been received by consumers and companies to be applied against home and garden field pests; these can also prove effective in agricultural situations, particularly for organic food production. This chapter provides a review of several different aspects relating to plant essential oils (EOs) including a historical perspective, main sources and antifungal activity, bioactive single constituents of EOs and their modes of action, and, moreover, the chemical measures necessary for controlling plant pathogens and their negative impact on human health and/or the environment. This chapter also reviews the different sources of plant essential oils. The antimicrobial activity of EOs, with particular emphasis on the antifungal properties exhibited against some serious pathogenic fungi and postharvest disease, is reviewed. Moreover, various antimicrobial tests and techniques are included.