Plant Health

Fungal spores that develop mycorrhiza and their effect on biodiversity


Report no: 2020:09

Published: 25.06.2020

Key message:

It is unlikely that the fungi and bacteria used in six mycorrhizal products could be detrimental to Norwegian nature.

This is the key finding in VKM’s risk assessment, commissioned by the Norwegian Environmental Agency. They required an evaluation of potential negative consequences for biodiversity, stemming from the import and release of these species for their use in Norwegian agriculture.


Mycorrhiza, a beneficial association between plant roots and fungi, is essential to plant growth in most natural terrestrial ecosystems and in agriculture. Commercial mycorrhizal products containing fungi and bacteria may promote plant growth, especially where no natural microbial community is found. In Norway, the addition of different fungal spores of mycorrhiza-forming fungi to agricultural products is a growing trend.


Most of the evaluated fungi and bacteria are probably already present in Norway. However, data is only found for two of the fungi.

We consider it as moderately likely that the assessed fungi could become established in the areas where the products being used, says Iben Margrethe Thomsen, Scientific Leader of the project team. The is moderate uncertainty regarding this conclusion.

The likelihood of the six bacteria becoming established ranges from very unlikely to very likely, depending on which type it is. There is low uncertainty about this conclusion.

The probability of spread to the wider environment ranges from unlikely (four fungal species), to moderately likely (two fungal species), to very likely (five of the six bacterial species).

However, for all species it is considered unlikely that establishment and spread would have negative effects on other native species, habitats and ecosystems in Norway, concludes Thomsen.

This risk assessment is approved by VKM's Panel on Plant Health.


lite bilde av Daniel Flø

Daniel Flø

Project manager, PhD

M: 91145274
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