Plants look dusty and is spreading

Sooo this was a problem when I first put my sage plant in our new garden a year ago but I thought it might just be the plant being transplanted/dust from planting it. Seeing as how now all the plants nearby look like they have the same problem to various degrees, I'm thinking it's mould/mildew/fungus?

What it looks like: like the plant has been dusted with fine soil. Some leaves turn yellow and drop off. The plants don't die but I'd hazard the vigour of the growth is affected. The marjoram also shows little white spots.

Related to aphids possibly? The garden does not get loads of sun, in part because of the position of my little front garden and in part because numerous neighbours don't cut their hedges. It has been a dismal wet summer.

I try not to leave leaves lying up but quite possibly have helped the spread by touching one plant then another. The plants are close together but not packed - I moved in to empty beds so have been trying to populate them, but slugs/wet weather/budget means progress is slow.

Aaaanyway, what is it? Can I treat it? Am thinking of cutting down older sage growth anyway - but when should I do it? How do I avoid spread?

 

Might it be rust? Maybe have a google about for images to see if it looks the same.

 

I did originally wonder if it was then read something about leaves looking rusty...and this is black dusty rather than rusty I will get a pic of the leaves to see if I can illustrate

 

Would it be sooty mould or mildew?http://en.wikipedia.org/wiki/Sooty_mold

Not terminal but it looks terrible.

I wouldn't expect to see it in the winter, though, but check it out.

If you plan to hard prune your salvia now you will probably lose most of this year's flower crop, which would be a shame as it is well worth having. I'm assuming it is a culinary salvia. You could cut it down when it has finished flowering, about mid June, and it will remain more compact. They do much better in good sunshine, though.

 

Could be mildew? I got a photo of the sage (yes the culinary type) and a nearby chrysanthemum



Neem oil says one page?