Any mildew will destroy leaf growth, search for a mildew control which will suit you, any animals and your surroundings.

Greenfly love lupins and cause all sorts trouble try blasting with a hosepipe or just cut off infected parts and bin.

thanks for the info. Since posting nearly all the leaves are affected now and it has gone powdery white rather than just a white film. i've cut the white leaves off, don't want to use a spray that will hurt insects. Hoping it will go away but I have to say, it's got a lot worse.