AQIS Chlorine Seed Treatment - Fact Sheet

What is chlorine seed treatment?

• Chlorine treatment is a process used to surface sterilise seeds for sowing. The most commonly used form of chlorine is sodium hypochlorite (NaOCl) solution (common ‘bleach’).
• AQIS treats certain seeds by immersing them in a solution of 1% sodium hypochlorite (1% available chlorine) for 10 minutes. Chlorine seed treatment reduces populations of pathogenic microorganisms on seeds but does not necessarily eliminate them.
• Chlorine treatment is also commonly used on dormant cuttings in post-entry quarantine.

Why use chlorine treatment on seeds?

• One of the ways plant pathogens are introduced into a new area is as an external contaminant on seeds.
• Chlorine is one of the most effective and widely used sanitisers in the world and it has been reported to eradicate or significantly reduce the incidence of plant pathogens, particularly bacteria and fungi, on the seed surface without affecting germination.
• Unlike hot water treatments used in quarantine, chlorine treatment does not eliminate pathogens within the seed, as it is a surface sanitising agent.

What seeds require chlorine treatment?

• Information on seed treatments and other import conditions can be accessed via the AQIS Import Conditions Database (ICON). ICON contains the current import conditions for seeds of more than 30,000 seed species. It can be used to determine if a species intended for import to Australia requires an import permit and/or seed treatment or if there are any other quarantine requirements.
• Carica papaya (papaya), Citrus spp. and Catharanthus roseus (periwinkle) seeds are examples of seeds requiring chlorine treatment.

Will chlorine treatment harm the seed?

• If importers are concerned about potential adverse effects of chlorine on seed germination, AQIS recommends they conduct their own trials prior to importing a large quantity of seed.