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Re: Powdery Mildew and other diseases

>  All my 'Green Ice' mini roses in my window boxes have powdery mildew.  I
> have cut them back to about an inch from the dirt, do I have to remove them
> so my other plants don't get infected- is it in the soil?   Also my peonies
> are mysteriously drooping in some of their stems.  I keep cutting off the
> affected ones- anything else I can do.  Lastly columbine leaves have I
> think mosaic virus, squiggly marks on the leaves- again I cut them right
> off but they keep coming back with more like that.

Sulphur dust or sprays are supposed to prevent mildew.  The fungus only 
grows on the surface of the leaves, and may create fruiting bodies with
overwintering spores.  It could be eradicated in a single treatment.

Not too sure about the peonies, but you should make sure that your shears
are sterilized as you move between plants, or you could be spreading
botrytis blight.  Is it a visible wilting, or are the stems just too
weak?  Some peony varieties just have weaker stems than others, cauing
them to droop.

The squiggly lines are probably leaf miners, which often plague columbines.
Malathion is the usual control for leaf miners, but I don't know if it
will have an adverse affect on columbines or not.

Chris


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