Ideas to help me deal with an insect infestation on herbs

Discussion in 'Edible Gardening' started by Matt Ellis, Apr 27, 2020.

  1. Matt Ellis

    Matt Ellis Apprentice Gardener

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    Hello everyone, nice to join your little community.

    I am a novice gardener, my wife and I bought our first place three years ago, we have a flat in Bristol city centre. We are on the fifth floor and are lucky to have two balconies, one facing mainly east and another facing southwest. We have plenty of pots, tubs, bags and troughs where we've grown mostly edibles on general purpose compost with some gravel thrown in to try to improve drainage.

    Towards the end of last summer we had a large number of insects on our mint, sage and thyme, and they almost killed off the sage. I guess they laid eggs and the adults died off over winter because they've just come back in force on the thyme (see the pictures). Only about ten days ago it was lush with new growth, but now there are vast numbers of these tiny horrors. When you brush your hand over it a few winged insects flutter around erratically. There does seem to be some stickiness on the side of the pot although they don't exactly look like the greenfly I've encountered before. Last year I used repeat applications of an organic insecticide which was fairly effective on the usual greenfly, but not so much on these. I think it was one based on rapeseed oil and an emulsifier.

    It's not an enclosed environment so I don't know if biological control would work. We try to encourage small birds, but they rarely come close to the flat. I think they don't expect to find our feeder and nest box up here, and they are put off by the large numbers of pigeons and seagulls.

    Any thoughts on what these are and any advice on the best methods of control please?
    20200424_122611.jpg20200424_122942.jpg20200424_122950.jpg

    Thank you!
     
  2. mazambo

    mazambo Forever Learning

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    The picture's aren't to clear, maybe white fly? Are they anything like this?
    greenhouse-whiteflies-2x.jpg
     
  3. ricky101

    ricky101 Total Gardener

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    Hi,

    Think they looks too small for true WhiteFly as @mazambo shows, though you may have the odd one flying around.

    They look more like typical Aphids which can be in a variety of colours and you see lots of white husks around on the compost etc where they have molted their skins.

    Because there are so many, think your only choice is a proper insecticide like Bug Clear which is safe for food crops etc, though do read the labels instructions.

    An alternative, but expensive is Nematoes, though some say they will only limit things, not erradicate them.

    Sometimes with such heavy infestations and where the plant is sickly, its just simpler to discard the plant and compost and start again in a clean tub.

    Sage and Thyme can get too woody with time and often worth getting younger more productive plants anyway.
     
  4. Matt Ellis

    Matt Ellis Apprentice Gardener

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    That's worth knowing, thank you. I rather hoped/thought that these plants would last a really long time, and I could eventually plant them out into a proper garden when I have one in years to come. I'd like to support my local garden centre but I don't know if I can get delivery on a new plant at the moment, and I don't want to wait for seeds to grow and become established.

    You are right ricky101, there are lots of white husks around in the compost. I took those photos on my phone, but I also have a DSLR around at the moment- usually it would be left at work- and I can try to get a better picture in a bit.
     
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