Question Red Spider (2 spotted) mite

Helen Auriga

Ecological Farming & Landcare
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Having big troubles with Red spider mite (Tetranychus urticae ) this and last year.

We have been tried:
1. Increasing the humidity (helped a little bit)
2. Released Californicus predatory mite (helped reduce mite numbers)
3. Released Persimillis predatory mite (helped reduce numbers).

The problem is that above 35C the predator mites can't reproduce and above 40C they only survive a few days. The temperature around here has been regularly over 40C for the past few weeks.

Does anyone have any ideas under to keep spider mites under control in hot weather?
 

ClissAT

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Hello Helen & welcome to the group.
What plants are they inhabiting?
Generally red spider mite will go for plants that are a bit unwell to begin with.
Check that there aren't any ants on the same plants.
If so treat soil with ant sand or simply spray the whole plant with something like pyrethrum.
Another way is to remove all the inhabited leaves which could leave your plant bare but will severely deplete the mite numbers too.
 

Helen Auriga

Ecological Farming & Landcare
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Hello ClissAT. They are on cape gooseberries. Yes picking off any leaves when you see the first signs of them definitely works, this years infestation has gone beyond that now, I think they over wintered in the soil then came back in force this year. We've been discussing discarding the plants and soil (they are in pots) and starting fresh.
H
 

ClissAT

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I think they over wintered in the soil then came back in force this year. We've been discussing discarding the plants and soil (they are in pots) and starting fresh.H

There's your answer! The pot mix is old & worn out, so the plants are struggling & have no resources to withstand the fresh onslaught.
If the plants are not bearing yet, you could try saving them by repotting into brand new potting mix after hosing off the old soil & the whole plant too.
Then spray with some garlic or pyrethrum & replant into new mix.
Then after a few days for the insect spray to take affect, mist the plants everyday for a week with weak Seasol.

I hope this edit is not too late for you H. I reread my post today then realised I may not have sufficiently clarified myself!
I meant to say when you hose the old potting mix off the roots & the whole plant also, to do that while you have the bare rooted plant in your hand so you can hold it upside down. Use the flat spray setting on the hand nozzle as that can get right under their webs under the leaves. This enables you to get under the leaves properly to hose those little blighters right off the plant. Do the hosing well away from any plants you don't want infested as they can march a good distance once on the ground. I think it is always worthwhile attempting to save well grown plants if possible as it is rather like saving time.
 
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