Question
i would like to know if i can buy a rose  that is black is there such a colour for a rose  and i have 4to 5 wild rose bushes they have a nice scent to them they are huge do i need to prune or cut old flowers of or can i just leave them to do there own thing  also i am spending to much on black spot treatment is there something i can make up instead as im a pensioner i have put so much on but it still does nothing can you help i have roses out the front of the house which get the morning and afternoon sun the ones out the back get full sun at about 10 oclock and still get the sun till 6  oclock im in western australia in a small town called collie it gets  hot and cold right now its nearly spring time we are fairley high up from sea level  im sorry if this is to much for you  but i will be gratefull for some help thank you  

Answer
To answer your questions. First there is no such thing as a black rose
only very dark purple ones. Rose genes do not contain any black in them
or for that matter blue ones.
Species roses bloom on the last years wood so if you cut them back, you
are cutting off some of the flowers. You can prune them right back if
you want to but you will have to wait until the following year for more
flowers.
The spores of black spot float around in the air and when it rains or is
windy, they are forced to the ground. If they land on soil or fallen
leaves, they soon die but if they land on a rose leaf then they start
their life cycle by pushing their roots below the surface of the leaf.
When they have killed that part of the leaf it goes yellow and you see
the black spots. Too many spots on the leaves will kill the whole leaf.
Good success has been attained by using a dormant oil spray in the
spring before the roses leaf out. Then you kill the spores that have
over wintered on the canes. The weather does have something to do with
this disease as fungus like damp and humid conditions to grow well.
There are also certain colours which are far more prone to black spot
than others, such as scarlet reds, apricots and yellow.  You can also
start to spray with any rose fungicide just as the roses are starting to
leaf out then you kill the spores that have over wintered on the canes.
Spray weekly for a month and then just once a month and you will see a
big difference in your roses. Make sure you alternate two different
sprays. Spraying on leaves that already have black spots on them is
useless The way current fungicides do help is by preventing new
infections. The goal is to have new growth coated with the fungicide
before any attack, so that when a spore lands, it lands in a pile of
fungicide, rather than on a clean and vulnerable leaf surface.
I wish there was something that one could mix up and use for black spot
but even the organic mixtures really don't do any good for a fungus such
as black spot. If you spray baking soda and water on roses every day it
will help to keep mildew away but you have to do it daily which is a
chore. The logical answer is to only grow those roses which are disease
resistant. That of course means the very old roses such as Gallicas,
Centifolias, Mosses, Damasks etc as they are completly disease free.
Even the modern shrub roses do well without a lot of fussing. When you
hear about roses being difficult to grow, it is always the hybrid teas
and floribundas they are talking about.
It appears that spraying the roses before they start to leaf out with
the tree spray of dormant oil and sulphur and then another spray of the
summer strength of the oil and sulphur is about the best thing you can
do to keep the fungus at bay. Constant spraying with the sane fungicide
doesn't work either as the roses get immuned to a spray and so you have
to alternate them at every spraying.
I have over 800 roses now and all I grow are the old garden ones, modern
shrubs, ramblers, the old climbers and about 25 hybrid teas in a
protected area. If a rose bush constantly gets black spot for three
years running, then it is given away to someone who is prepared to spray
constantly. At my age I am not prepared to be a slave to roses! Hope
this helps. Lynnette