Help! Nectarine tree is being covered in strange webs

I've got a dwarf nectarine tree that has fruited this summer but is now being covered in a weird spiderweb type substance on the leaves. It's in a polytunnel. Can anyone advise what it is and how I tackle it? I've tried cutting off the infected branches but it keeps reappearing. Apologies if it's an obvious problem - I'm a newbie gardener! Thank you.

 

Looks like red spider to me Carolien

Red spider likes warm dry conditions......spraying with water helps deter them.
There are chemicals but on edibles I would not use them.
I would simply try and wash your tree for now but for next year spray regularly....hose is as good as anything

 

Looks like a very advanced state of RSM.
You could try predators but probably a bit too far advanced for this year.

 

Thank you very much.

 

Thank you very much.