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Help With Aphid Invasion

My workplace has a polytunnel and the person in charge let the plants in there become infested with aphids. I mean every inch covered with aphids side by side and they had grown wings to signal that even they knew it was crowded in there. Before I knew this, I had started growing some plants in a separate greenhouse and they inevitably became covered too. I spent hours removing every insect from my chilli plants and took them home to quarantine them, they have remained almost clear, one plant will occasionally see a few on the level which I promptly remove.

However today I was so disappointed to see my borage plants covered in aphids. Chillis are still free from aphids, so I've moved these away until I decide if I have the energy to tackle the borage now. Has anyone ever cleared a heavy infestation? What can I do? I want to start fresh at work and grow salad and plants to sell to raise funds for the children there, but what's the point if they will all become covered in aphids? Any idea how to completely eradicate and start a new growing season clean and healthy and disease free?



  • ObelixxObelixx Posts: 29,130
    I don't like using chemicals a sthey are indiscriminate so my usual approach when I see them on my roses and one tender hibiscus houseplant is to squish as many as I can with my fingers and then spray off the rest with a blast from the hosepipe or shower head as appropriate.  For the roses, I then keep an eye on them and hope the ladybirds, hoverflies, lacewings and blue tits will be along to hoover up the rest.

    The RHS offers this info on its website - and if you scroll down to the link to biological controls you'll see there seem to be some available for aphid infestations.   They may be temperature dependent tho so, until it warms up I would suggest you try to empty all plants out of the polytunnel and clean them up and then keep them elsewhere while any remaining aphids in the polytunnel die of starvation.

    As a last resort/insurance policy, you could also try closing the doors and spraying with a pesticide all over the inner walls and the soil as the enclosed space would limit damage to beneficial predators and pollinators.

    Then you just have to put all new plants in quarantine before they go into the PT after you're sure they're aphid free.   Unfortunately, one little aphid can soon become thousands as they can and do clone themsleves very quickly.

    Vendée - 20kms from Atlantic coast.
    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
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