Impatiens downy mildew - curses!

Just had to dispose of two lovely orange impatiens that had been struck down with this rotten disease - suddenly realised they were looking a bit sick and on investigation they had fine white powder on the underside of their leaves.

Now have a gap at the front of my border and am paranoid for the welfare of the double impatiens planted nearby. There's not even anything I can do to protect them apparently. Arrrgh.

Sorry, just had to vent.