Check it's from them. I doubt it. I wouldn't mind betting that's seed being shed from some nearby poplar trees. Phil J

Ah, you must be the Guest who asked earlier, Flack, welcome. Could be woolly aphid, could be button or some other form of scale, could be mealybug - if you can't post a picture, then suggest you google those three conditions for pictures to ID your problem. There are many forms of scale, some of which produce large amounts of white fluffy stuff, and a lot which don't.

Check out your previous question, Flack. I've left some advice there.

Interesting and highly possible suggestion from Philjeffs there - be great if it was just that, no need to do anything, lol!