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I am growing a lemon tree indoors. It got infested with spider mite (at least I think that based on the look of it see picture at the end).

I noticed it bit late and it caused my lemon tree to loose all leaves on 1 branch.

I applied this spray against bugs, but wonder if I should do something more. Do I need to prune infested branches and cut them off or will the spray be enough? Is there anything else I can do to help the tree survive? Should I also clean the leaves with water?

Picture of infestation here:

enter image description here

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  • What is the active ingredient/s in the spray you used - I can't seem to find that information on line? Just trying to work out whether it will work against spider mite because it only mentions aphids...
    – Bamboo
    Jun 1 at 16:24
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    @Bamboo According to the Google-translated version of that webpage, the active ingredient is deltamethrin.
    – csk
    Jun 1 at 17:06
  • @Bamboo yes deltamethrin
    – 1muflon1
    Jun 1 at 17:20
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That's a pretty severe infestation but not uncommon on indoor citrus. In order to control them you have to understand what the control agents do. Whether it's deltamethrin, neem or dish soap these are all contact pesticides. They have to coat the spider mite to kill it.

The webbings are an effective way of preventing sprays from touching the adults and the eggs.

A very effective way of controlling spider mites is mixing 5 ml of dish soap with one liter of water. Then take a cloth and get it good and soapy. Wipe down every leaf and stem and then repeat three times at five day intervals. This will get any eggs that hatch later. After wiping the plant down send it to the showers to wash the soap off.

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  • thanks by the way do I need to wash just the green parts or the whole tree?
    – 1muflon1
    Jun 1 at 19:10
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    If you are going to go to the trouble do every thing. Eggs can be laid on the stem or trunk so you want to get those too
    – kevinskio
    Jun 1 at 19:11
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    @1muflon1 I would start with the non toxic easy to do solution. If it doesn't provide the results you want then escalate to neem oil or more permethrin based solutions
    – kevinskio
    Jun 1 at 19:38
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    @1muflon1 Citrus bud out readily from green and even woody stems. remove all dead and dying leaves, move to better light, cut back water a bit and wait up to a month. New leaves will bud out
    – kevinskio
    Jun 4 at 15:42
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    @1muflon1 No feeding, the plant is stressed, any fertilizer with nitrogen will force the growth of new leaves. Patience is your ally to let the plant recover naturally
    – kevinskio
    Jun 4 at 16:56
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Thanks for clarifying the active ingredient. Although that product is said to be kind of effective against spiders, spiders are not spider mites, so I'm not entirely sure it will work on spider mite, though it's more likely it will than not.

If it doesn't work, I'd suggest you try neem oil spray instead next time, which is a more natural and less harmful (to humans and animals) substance than deltamethrin. There is nothing else you should be doing to get rid of the mites as well as spraying, although increasing humidity around the plant will help - spider mites like dry, hot conditions, so misting occasionally with ordinary water might help. If you are intending to move the plant outdoors during summer, spider mites are less likely to be a problem, until you bring it back inside again for winter.

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  • Thanks for the advice, by the way I think that one of the new branches that lost a lot of leaves is most infested (I see a lot of mites crawling up and down on it) does it make sense to just cut it? Does the mite get inside the branch or is it just leaves
    – 1muflon1
    Jun 1 at 19:00
  • Just affects the leaves, though over time if the damage goes on long enough, then dieback can occur. If the branch appears dead or dying, remove it - if its not that bad, leave it because once the mites have been dealt with, it might put out new growth. I'm slightly worried by the fact you can see mites moving, even though you've already sprayed the plant though ...
    – Bamboo
    Jun 1 at 19:13
  • oh sorry, I used wrong tense, I seen them crawling before I sprayed the plant, the spray seems to have helped a bit (relative to the morning although I still see 1 or 2 moving)
    – 1muflon1
    Jun 1 at 19:16
  • Ah, okay,hopefully they will die off shortly.
    – Bamboo
    Jun 1 at 19:17

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