Orange crusty leaves causing shrubs to die back

For the last couple of years a previously healthy lavetera bush has become infected with something causing every leaf to suddenly die covered with orange crustiness despite having looked fine for a bout 3 weeks.  this year this seems to have spread to my Moroccan broom tree which is about 12 feet away  this is a well established tree but this year looks very sorry for itself. Despite lots of research I have been unable to discover what might be causing such catastrophic damage and what to do about it. If anyone has experience of this I would be grateful for any advice please. I am happy to dig up the bush but would dearly love to save the lovely pineapple tree. Thank you