Red spider mite on Nectarine

I have a small Nectarine tree (fan-trained 4-5 years old) in my lean-to greenhouse. This year, for the first time, I had lots of fruits and they were growing nicely.
Towards the end of July I noticed that it was looking a bit "off", the leaves were starting to take on a faint yellowish, mottled look. The same applied to my cordon tomatoes.
Off I went on holiday for two weeks, with my clue-less (as far as gardening is concerned) son doing the watering. On my return there was no doubt, Red Spider Mite with quite a lot of webbing present.
I pulled the toms out right away and sprayed the tree with the recommended Bug Clear Ultra, according to the instructions. Re-applied after 14 days as advised. As the leaves fall, I collect them and get rid of them.
Now, dear gardeners, what else can I do to avoid this happening next year? Can the mites overwinter somewhere? The greenhouse sits against a really old stone wall, with masses of holes and cracks in it, mite heaven perhaps? The tree is very close to the wall.
Apart from a Dahlia (large) there are no other plants inside and this is the first time I have had any problems with pests or deceases in there.
By the way, I harvested all the fruit before spraying and they were fine, apart from a bit unripe! Any advice would be greatly appreciated.

 

Hello ellabella, They probably will re-appear next year once it gets hot and dry. As the problem is in a greenhouse, your best bet for getting rid of them in future would be a biological control called phytoseuilius. If you Google it, there are various suppliers in the UK. It's a predator that feeds on the mites and it really does work!

 

I used to use the preditory mites and they do work, trouble I found was it ran out pretty expensive as you need new introductions all through the summer.
And they aint cheap.

There are pesticides out there that work well, and only one application each year, but do they let the amatuers buy them, no way.
If you know a fruit farmer just mention it.

 

Thanks noisette47, I will look in to the biological control!

 

Thanks Pete,
Alas, I don't know a fruit farmer, that would have been handy!
I will have a look at the predators, but will remember your advice re cost......

 

Just out of interest, this is what the professionals use.
There are probably others.
Its a very simple one spray early in the season.
http://www.bayercropscience.co.uk/our-products/insecticides/envidor/