Report from the Sub-comittee on the environment and health

Conclusions concerning
environmental impacts
182
The following specific conclusions can be drawn:
• With a total phase-out of pesticides, direct exposure of flora and fauna
in terrestrial and aquatic ecosystems due to spraying and spray drift
would end immediately, and exposure via run-off would be greatly
reduced within about one year. However, it would take considerably
longer for <strong>the</strong> flora outside <strong>the</strong> cultivated areas to re-establish.
• Stopping seed-dressing would remove a risk to birds and small
mammals, which eat <strong>the</strong> seed.
• If <strong>the</strong> mechanical weeding were very effective, <strong>the</strong> amount of weed
would not differ significantly <strong>from</strong> <strong>the</strong> amount in fields treated with
pesticides, so <strong>the</strong>re would be no environmental benefit for <strong>the</strong> flora in
<strong>the</strong> field itself. On <strong>the</strong> o<strong>the</strong>r hand, mechanical weeding would be of
great importance to adjacent areas and small biotopes, since <strong>the</strong>se
would no longer be affected by spray drift.
• It is considered that mechanical control of couch grass in <strong>the</strong> autumn
would have a negative side effect in <strong>the</strong> form of increased nitrogen
leaching during <strong>the</strong> winter months because of increased nitrogen
mineralisation, while mechanical control in <strong>the</strong> spring is also known
to increase nitrogen metabolism, which is often seen as having a
positive effect on crops, which have a good possibility of utilising <strong>the</strong>
released nitrogen in <strong>the</strong> growth season.
• Mechanical weed control can have a considerable negative impact on
<strong>the</strong> soil’s mesofauna and macrofauna – particularly springtails and
earthworms. However, a clearly beneficial effect is achieved with a
diversified crop rotation with 2-year clover.
• Increased soil treatment could increase <strong>the</strong> risk to farmland birds,
which nest in <strong>the</strong> midfield.
• The use of beneficial organisms and microbiological products for
biological control of pests in <strong>the</strong> field would involve a serious risk of
proliferation of foreign organisms, which could have an adverse effect
on <strong>the</strong> environment. Theoretically, <strong>the</strong> proliferation of indigenous
species could also upset natural ecological balances. In Denmark,
beneficial organisms have been used for a long time to combat pests
in greenhouses. The species used cannot survive outdoors and can
<strong>the</strong>refore not spread.
• Genetically modified plants that are resistant to insects could affect
o<strong>the</strong>r species than <strong>the</strong> pest – for example, predatory insects and birds
that eat herbivores living in <strong>the</strong> genetically modified crop.
Fur<strong>the</strong>rmore, possible effects of insect-resistant plants differ <strong>from</strong>
those of spray products in that <strong>the</strong>y last for <strong>the</strong> whole of <strong>the</strong> growth
season. However, it is likely that some non-target organisms would be
less affected by genetically modified plants than by conventional
spray products. Genetically modified plants that have instead been
made resistant to fungi and viruses would be gentle with <strong>the</strong> insect
populations.