I was at my wits end 8yrs ago when I first encountered YBS & was culling left right & centre ....when I happened to mention this to a local fancier he said not to kill but to give Garden Lime in the water, but with strict instructions on how to administer this in the water, I was sceptical but despartate I had tried everything else so I gave it a shot .....I'm still using it years later so you can gather that it worked.
Stevie Barbour