Plant health: risks linked to import of soil and growing media

EFSA’s plant health experts have investigated the risk of harmful organisms and other non-native species entering the EU via soil or other growing media. The work was requested by the European Commission to support a review of the existing rules on the introduction of soil and growing media into the territory.

The review is in response to concerns that the current measures may not be sufficiently effective at preventing the entry of harmful organisms through this route.

EFSA’s Scientific Opinion uses the International Plant Protection Convention’s definition of a growing medium as “any material in which plant roots are growing or intended for that purpose”.

More than 800 types of soil and growing media that could be used to grow plants were identified through an extensive literature search. EFSA’s Plant Health Panel (PLH) consolidated these into eight groups – such as “media including plant materials”, “animal manure” and “synthetic media” – and assessed the likelihood of each group being a means of transmission for harmful organisms.

The great majority of the growing media identified by the literature search – 678 out of 880 – included plant materials. These media are highly diverse and include compost, food waste, green manure, straw and bark.

Among the growing media not containing plant material, the main groups were: inorganic media, such as sand, volcanic rock and gravel (78 types); growing media that have been processed to eliminate plant pests or reduce their presence (73 types), such as ash, tannery sludge, molasses and coal; and synthetic media (27 types), such as polymers, polyethylene terephthalate (PET) bottle particles and polystyrene granules.

The PLH experts assessed the effectiveness of measures such as heat treatment, use of pesticides and fumigation to reduce the presence of harmful organisms in soil and growing media. The Panel indicated that these treatments are not 100% effective in all cases and their effectiveness depends on several factors, such as soil characteristics, the type of harmful organism and the application procedures.

As part of its assessment, EFSA’s Panel evaluated the effectiveness of the current EU measures for controlling the introduction of soil and growing media into the EU and examined the legislation that is in place in several non-EU countries – Australia, Canada, New Zealand and the United States – covering plant quarantine, biosecurity, soil, growing media and fertilisers.

This review highlighted the importance of clear formulation and guidance on the implementation of measures for soil and growing media. Effective measures identified by the Panel include import prohibition and options related to pest-free production sites and preparation of consignments for transport.

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