Q.How do I get rid of Box Blight on my Conifer Hedge
The hedge has been there approx 30 years & is cut once a year. After cutting it this year it has all started going dark brown in big patches, Then there is like webs all over it like spiders webs. It looks like spray snow!!

Certified GKH Gardening Expert
Without a photo, I can guess at a few things. This could either be webworms, or likely spider mites.
These articles will help:
https://www.gardeningknowhow.com/plant-problems/pests/insects/spider-mite-treatment.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/controlling-fall-webworms.htm