Methods of analysis for the in vitro and in vivo determination of the fungicidal activity of seaweeds: a mini review

Biosecurity is emerging as one of the most important issues facing the agricultural and forestry communities, with the use of chemical pesticides being the main protocol for controlling plant pathogens. However, as a result of the emergence of resistance against these controls and the negative impact chemicals have on the environment, coupled with more stringent European Union regulations, this will have to change. The search for safer alternatives has begun, with seaweed becoming an interesting focus as a potential biopesticide due to its ability to produce a broad spectrum of chemically active secondary metabolites. These secondary metabolites possess biological properties including antimicrobial, antioxidant, anti-inflammatory, and antifungal. There is a need to develop reliable methods with the ability to rapidly screen and evaluate the potential pesticidal activity in seaweeds. This review focuses on the current methods used to investigate the fungicidal activity of seaweed extracts including in vitro methods namely disk diffusion and in vivo methods namely, the screen-house study and the advantages and disadvantages associated with each method. It was concluded that no one method is suitable for all test organisms or extracts after careful consideration of the literature. Additionally, this review confirms the promising potential of seaweeds as biopesticides with studies demonstrating that seaweeds are active against a wide variety of fungal diseases. It was noted that further research needs to be carried out on the isolation, purification, and identification of the bioactive compounds present in seaweeds in order to facilitate the future potential application of these novel biopesticides.