Botanical active substances: a prospering field of research

Since months, the Journal of Plant Diseases and Protection receives a rising number of submissions concerned with the search for alternatives for chemically synthetic pesticides. In the centre of interest are simple plant extracts including botanical active substance like essential oils for use in plant protection. The term ‘botanical active substance’ covers an extremely heterogeneous group of substances ranging from simple plant powders to unprocessed and processed plant extracts. Furthermore, plant extracts may be highly refined (i.e. one single active substance) or represent a complex mixture of components of which all or only some are biologically active. This topic collection focuses on botanicals in plant protection, particularly natural plant extracts and essential oils. These active substances have gained popularity as alternatives to chemical–synthetical pesticides, as they are assumed to offer benefits like low toxicity and environmental compatibility for sustainable agriculture. The collection includes 12 selected papers from different countries summarizing recent studies on the effectiveness of natural products in controlling pests and diseases of economically important food crops in agriculture, as well as their potential use in systemic acquired resistance and reducing pesticide residues. Substances referred to as analogues, mimics, naturalidentical synthesised molecules and biosimilars are not covered by these research reports. This shows that we might be at the beginning of a development not to explore botanical actives as resource for industry but for direct use by farmers as self-preparations. The issue starts presenting the European Union legislative situation on the use of botanicals in plant protection. Regulation (EC) No. 1107/2009 requires evaluation and authorization before any substance can be marketed as an active ingredient in a plant protection product. This regulation does not cover botanical extract which are produced by farmers and used directly on the own field without being placed on the market as a plant protection product. In the articles published here but in former issues also, a ‘botanical active substance’ consists of one or more components found in plants and obtained by subjecting plants or parts of plants of the same species to a process such as pressing, milling, crushing, distillation and/or extractions. The process may include further concentration, purification and/or blending, provided that the chemical nature of the components is not intentionally modified/altered by chemical and/or microbial processes. The authors reported pesticide properties of plant extracts, essential oils, plant-derived powders and other natural or processed plant derived materials as potential insecticide, acaricide, molluscicide, rodenticide, fungicide, antiviral, herbicide or resistance inducers in plant protection. Repellency and antifeedant characteristics of botanical substances and the potential use in plant protection programs were described, even allelopathic effects were also discovered. Exemplarily, the use of botanical substances was matter of these studies: