How can I prevent or control rust on campanula glomerata superba?
This is a tricky job as rusts are difficult to control. Collect up the dead stems and foliage at the end of the season and dispose of it in the dustbin rather than composting it. You could water the soil around the base of the plant with Armillatox during the winter in order to kill any over wintering spores. Next spring as soon as the foliage opens out treat it with either Bio Systhane Fungus Fighter or Dithane 945 repeating the dose at least twicw at 10 day intervals. It is a bit of an uphill task but if you give it a go and maybe do more fungicicde sprays over the growing season you could well improve the situation.
