Allotment Gardening Advice Help Chat

Growing => Growing in Greenhouses & Polytunnels => Topic started by: MichelleC on May 23, 2011, 19:07

Title: Red Spider Mite in my greenhouse?
Post by: MichelleC on May 23, 2011, 19:07

I've recently noticed a slight mottling on my squash leaves in the greenhouse. After a little research I think it may be red spider mite. I didn't use a magnifying glass but I can see clear lone eggs, I think. There are no webs as yet.  Can I just spray these with water or should I use a soapy or oil spray on them? Any help much appreciated as I'm down the lottie tomorrow. x

Title: Re: Red Spider Mite in my greenhouse?
Post by: Babstreefern on May 23, 2011, 19:11

You can use soapy water, but I tend to use the insect/bug killer spray, and make sure you kill them.  Also they usually come in from outside, so check the guttering of your greenhouse and other hidey holes - they're not difficult to miss.  If you see them then you can definitely pour on soapy water:)

Good luck - one thing when you get damp/wet weather and its humid as well, you will nearly always get red spider.  So keep an eye out.

Title: Re: Red Spider Mite in my greenhouse?
Post by: mumofstig on May 23, 2011, 19:26

I think you'll find that red spider mite prefers hot dry conditions,  keeping plants sprayed with a fine mist of water, specially under the leaves, is a good way of controlling them.
Bifenthrin which used to kill them, is now one of the withdrawn insecticides :(

I've had it badly on some of my houseplants this year, and have been misting them daily!

Title: Re: Red Spider Mite in my greenhouse?
Post by: MichelleC on May 23, 2011, 19:28

Thanks for the reply. Can I just check one thing. I thought I read somewhere that by spraying your plants and wetting the floor makes it humid and the spider doesn't like that. It prefers hot and dry conditions or am I wrong?

Title: Re: Red Spider Mite in my greenhouse?
Post by: mumofstig on May 23, 2011, 19:30

Quote from: MichelleC on May 23, 2011, 19:28

It prefers hot and dry conditions

That's what I just said  ;)

Title: Re: Red Spider Mite in my greenhouse?
Post by: MichelleC on May 23, 2011, 19:34

Sorry. I replied to the first posting before seeing yours. I have lots of plants in the greenhouse waiting to go out. Shall I spray everything one of them or wait until I see sign of this spider?

Title: Re: Red Spider Mite in my greenhouse?
Post by: mumofstig on May 23, 2011, 20:24

You can see them as little brown dots if that's what you have, and eventually the webs covered in dots.
If you think you have them I would water the path/borders well to encourage humidity and dscourage them a bit.
Get the stuff outside as soon as you can, cos they don't usually last long outside in the open.
If you're sure that's what they are, or you get webs start spraying.
RHS suggests

Quote

plant oils or extracts (Vitax Organic 2 in 1 Pest and Disease Control, Growing Success Fruit & Veg Bug Killer, Scotts Bug Clear for Fruit & Veg) or fatty acids (Bayer Organic Pest Control, Doff Greenfly and Blackfly Killer or Greenfingers Organic Pest Spray) or urea/mineral lattice (SB Plant Invigorator),