Is there an effective way to treat roses for powdery mildew and...?

Question

black spot naturally? Any successful recipes?

Answer 1

For powdery mildew, I have read that it grows in a very narrow ph range. To thwart it, mix 1/2 milk and 1/2 water in a spray bottle, and spray the leaves. This changes the ph enough so the powery mildew doesn't grow.

Note - this will not remove powdery mildew - I know of NOTHING that will remove it once it appears. It will just prevent its occurance.
I tried it last year - but it was toward the end of the season, so I don't know if it worked, or if the mildew was "done" for the year anyway. I will be trying again this year. You need to re-spray after each rain...but then again there is nothing bad for the environment in the mixture, either.

If you can improve air circulation through pruning or removing encroaching platns, that could help a lot, too.

Answer 2

Prune into a vase shape to increase air circulation. When you water do not water on the leaves water at the roots eg drippers.
Mulch with hay etc at the roots to cover the soil that harbours the blackspot spores. Remove any prunings and burn so you don't keep the cycle going. Hope this helps.

Answer 3

I agree, good air circulation is very important. Meanhwile you might try plain old sulphur from the pharmacist.

Answer 4

transplant to a drier location with more air circulation.