Episode 177: biological controls part two
Yellow sticky traps can help to catch adult fungus gnats while nematodes deal with the larvae. Photograph: Andermatt UK.
Transcript
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Listen to the second part of my interview on biological controls for pests, plus I answer a question about an Oxalis and give an update on the sowalong, and we hear from listener Tate.
If you haven’t heard episode 176 yet, hold off listening and head over to part one of my chat about biological controls, which is here.
(If you want to check out the dryer rack you can hang on a window to display plants, as suggested by Scottish Plant Dad, here’s a couple of examples from Argos and Amazon.com.)
Amblyseius andersoni are supplied in slow-release sachets to treat red spider mite. Photograph: Ladybird Plantcare.
This week’s guests
Tessa Cobley of Ladybird Plantcare sells biological controls to UK gardeners for pest control on plants inside and outside. She is on Instagram as @ladybirdplantcare.
Dr Andy Brown is managing director of Andermatt UK. a manufacturer and seller of biological controls. Follow Andermatt UK on Twitter here.
Check out the notes below as you listen…
Mealy bugs
Brown Australian ladybirds (Cryptolaemus montrouzieri) can be used to treat mealy bugs, but they are best used in large greenhouses full of plants rather than a couple of plants. They need good light levels and a temperature of more than 20C.
When these ladybirds are used on larger plants, they are often contained with fleece to stop them flying away. Check out the University of Exeter’s use of Australian ladybirds as biological controls on trees in their atrium here on the university’s blog and also on Instagram.
For more on mealy bugs check out my episode on these pests here.
BTI
BTI stands for Bacillus thuringiensis subspecies israelensis: this is a biological control made from a group of bacteria that produces toxins which kill the larval stage of flies in the order Diptera, which includes fungus gnats, aka sciarid flies as well as mosquitoes. They are usually sold in the North American domestic market as Mosquito Dunks or Mosquito Bits.
BTI is not licensed for use in the UK so is hard to get hold of in this country, but it is seen as being a very safe product.
For treating fungus gnats, you can add the Bits to potting mixes when potting up.
Thrips
Thrips are another common pest of houseplants - there’s a good RHS page about thrips here.
Cucumeris (Neoseiulus cucumeris) - these predators come in slow release sachets and eat the larval stage of thrips
Amblyseius swirskii requires higher temperatures (20C) to work and also come in sachets, but it ins’t licensed for domestic settings (ie non-professional growers) in the UK. (You can see the full list of biological controls that are licensed for home/professional use in the UK here.)
Nematodes such as Steinernema feltiae can work on thrips in their larval form.
Orius (Orius insidiosus), aka the minute pirate bug eat all stages of thrips and are the most effective treatment. You can watch a video showing orius at work here.
Sticky traps vary in colour as different pests are attracted to different colours. Photograph: Ladybird Plantcare.
Scale
Scale insects can also be controlled using a foliar spray of nematodes.
I treated scale on my Pellionia repens with frequent sprays of SB Plant Invigorator.
While waiting for your biological controls to arrive, if you’re planning on using horticultural soap sprays or a product such as SB Plant Invigorator Tessa recommends stopping using such sprays the night before the biological controls are applied to make sure you are not killing off beneficial insects.
Mites - on my face?!
Yes. There are mites that live on human skin. More here, if you dare.
Sticky traps
These are useful for early warning about pests in your home, and can also help in terms of controlling the adult population of things like fungus gnats. The grid markings on many traps allow growers to keep an eye on numbers of insects caught. Different colours work for different pests depending on what colour the adult pest is attracted to - here’s a guide. Yellow for fungus gnats, blue for thrips, yellow patterned for whitefly and red for leaf hoppers.
Sowalong update
Thanks to all of you who are sharing your sowing successes (and failures!) on social media. Remember to include #OTLsowalong so I can spot your post and give you a shoutout on the show! Join Houseplant Fans of On The Ledge on Facebook to chat with other listeners about your seed sowing - remember to add OTLsowalong as a topic when posting.
If you haven’t listened to all the episodes talking about the sowalong, there’s a complete list here: and if you want to grow chillies indoors, do listen to my chilli episode too.
If you want to check out the cactus and succulent sowing leaflet I mentioned, it’s here.
Clare’s falseleaf shamrock.
QUESTION OF THE WEEK
Clare emailed about her Oxalis triangularis subsp. papilionacea, aka purple falseleaf shamrock. She was worried because the plant’s corms are close to the surface, and she wonders whether they should be planted deeper. The wonderful thing about this plant is how adaptable it is: normally when planting corms or bulbs, the rule is that they should be planted at least 3 times as deep as the diameter of the bulb/corm. I have buried Oxalis corms deep and left them almost on the surface, and they grow either way, but planting deeper does help to anchor the fragile stems of the plants, and also prevents corms from drying out.
The other Oxalis I mention as worth growing are Oxalis corymbosa ‘Aureoreticulata’ and Oxalis tetraphylla 'Iron Cross'.
Do listen to my Oxalis episode for more on these wonderful plants!
Want to ask me a question? Email ontheledgepodcast@gmail.com. The more information you can include, the better - pictures of your plant, details of your location and how long you have had the plant are always useful to help solve your issue!
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CREDITS
This week's show featured the tracks Roll Jordan Roll by the Joy Drops, Chiefs by Jahzzar, Rashem Pidity, Pokhara by Samuel Corwin and Sundown by Josh Woodward.