Chitosan is one of the few cationic polymers in nature.
Chitosan is a natural carbohydrate extracted from either the shell of shrimps or the cell walls of fungi.
It can be used as an organic biofungicide as it is listed as a ‘Basic Substance’ by the EU (regulations 1107/2009).
In agriculture, it can be used as a biostimulant to promote stress resistance, activate plant defences and improve the efficacy of co-applied chemicals and microbials.
It can be used by both conventional and organic farmers.
Chitosan is a potent elicitor of plant defence mechanisms. Plants detect chitosan as ‘non-self’ and signal that a pest or pathogen is attacking them. The crop plant itself defends against the pathogen, rather than direct biocidal activity, which is how conventional fungicides work.
Because of this mode of action, chitosan is best used preventatively rather than curatively.