Bob said

Don't forget that there are many areas of the world that do not have
problems with blackspot, rust and mildew at all.

And therefore it is completely pointless for people in these areas to
spray their roses with lime sulpher oil or any other winter applied
fungicides.

To the best of my knowledge, FEW IF ANY rose growers in my area do it
for example. It just isn't necessary for people in dry air climates.

Your advice is good in areas that have bad fungal infections, but
realize that that is not everywhere.

Bob Bauer
In the Arid Western USA


I guess in the first message (the reason why I placed the second) for some
unknown reason this paragraph was missing (it can be seen in the answer
that went as an answer instead of the message again who knows why):

" The winter season is the time to apply dormant oil sprays to plants, for
the control of insects and disease. Covering the dormant stems of a plant
with a highly refined oil such as Cookes Dormant Oil Spray suffocates
overwintering insect eggs and fungal spores. Before you spray make sure to
clean up the fallen leaves around your plants and remove any left over fruit
that may be still hanging on your trees. Roses can also benefit from the use
of horticultural oils in the control of black spot, powdery mildew and rust.
Powdery mildew can be effectively controlled by using a mixture of 2 Tsp. of
Baking Soda with 2 Tbs. of Horticultural Oil in 1 Gallon of Water."

We personally continue to stick to Bordeaux because the above formula did
not work very well for us, but this is black spot, rust, mildew, you name it
country. And we spray the second and third time to smother egg sacks and
larvae.

Allegra