Plants interact with their environment by sensing elicitor molecules produced by infecting fungi, bacteria and viruses. These bind to special receptors in the plant membrane and trigger defence responses such as production of plant proteins with antifungal and antimicrobial properties. The seaweed storage carbohydrate laminarin has been shown to trigger the same response and has been used as the basis for a protectant systemic spray (Scyon) to improve disease resistance in many crops.
How it works
Crops exposed to laminarin, found in seaweed, produce a disease signalling pathway in the plant. These signals lead to expression of proteins with antifungal properties, and also defence enzymes which produce compounds which have antimicrobial properties. Products such as Scyon are claimed to activate both pathways but are protectant only. The target application period is early season as a protectant spray when used in mixtures with conventional chemistry. Laminarin products are systemic and non-toxic.
Farmer / Agronomist benefits
Although yet unproven, biopesticides such as Scyon used as a protectant and applied mixtures may play a helpful role in reducing fungal resistance risk to conventional chemistry providing they work in an aligned time period. Used on their own, biopesticides have the advantage of being inherently less toxic to humans and the environment, they don’t leave harmful residues, and are usually more specific to target pests.
University of Santiago