Cobwebs on compost

I wonder if its from the compost? As you,ve used the propagator for some years you,d know if its too wet etc.

Are there any caterpillars anywhere you can see, at either end of the silky path/trail through your seedlings?

its not a fungi bye any chance as they like dark warm conditions and can look at a glance like spiders web ?

Noseypotter's suggestion 'rings a bell'!! Did you ever have mushrooms, or mushroom compost in your compost? If so, then it could well be a fungi of some sort and you will need to treat with appropriate fungicide.

Thanks for responses. The compost was a bag of multipurpose which was bought last year but was unopened until mid Feb this year. I have since stopped using it and purchased fresh as I also had problems with cabbage seedlings - were fine until I pricked them out into individual pots and returned them to the propagator where they slowly succumbed one by one to some sort of wilting disease. I don't think it was damping off as the stems were (and still are) strong and sturdy. The seed leaves withered, and looked a bit like powdery mildew. I sprayed with a solution of bicarb of soda and soap but it hasn't stopped the continuing demise of every plant leaf by leaf. I have now resowed all varieties - fingers crossed. I'll use the bag of compost on my ornamentals!

your more than welcome .