Black marks on rose leaves

We have recently seen what looks like black marks on the leaves of one of our rose bushes. Can any one tell us what it is and what we should do to get rid of it. Just hope it is not some sort of disease. See pic.

 

Thanks. Probably get some sulphur spray later today as we don't want it spreading to the other roses.

 

With respect, may I ask
Apart from being unsightly on the leaves does the black spot do the flowers any harm ?
If the leaves are really badly affected - all the leaves - should they all be picked off and leave the plant denuded.
I've had roses with the leaves with blackspot but they flowered wonderfully.
Fortunately I don't have it now (I thought it was down to pollution in my last garden)
Is there anything I can do to avoid it.

 

Not a rose grower by any means but as I understand it black spot being a fungal disease is actually killed by pollution, which is why sulphur is used as a remedy.
i've seen some rose bushes without any leaves by August around here and they look awful, one reason why I dont bother with roses.

 

We live in the country so no pollution here, well not like in the cities. As it is probably about that time now, we will probably prune the roses right down at the same time removing the leaves with fungus on them. Only one plant was affected.

 

I get black spot badly on one particular rose. I started spraying my roses early Spring as soon as the new red shoots appeared, at fortnightly intervals. I seemed to have quite good success, but over the past few weeks it has started to appear Do I have to keep treating them through the Autumn/ Winter when there are no leaves ?

Thank you

Blue

 

Thank you WOO. That's very informative.

 

We have had pretty much no black spot all Summer, and only sprayed them a couple of times (despite best-intentions and a reminder in my Electronic Calendar that has been bugging me repeatedly!! to spray them every two weeks).

We now have a lot of black spot, having had a very wet Autumn and now some mild weather.

I agree with WOO that having their leaves mucked about with by the fungus weakens the plant, and that then means it gets more diseases. People who come here always remark how healthy my Roses look - well ... its not that I mollycoddle them I'm afraid, I just don't have time. But we are pretty fanatically about removing diseased leaves, and we do spray "now and again".

WRT the perennial debate on pruning.

I find that wherever I cut in November there is some die-back on some stems by Spring. So from that I have concluded that cutting half-way back in November (to stop the plants being knocked / rocked about by the weather) and then pruning hard in February seems to be for-the-best as the outward facing bud I prune to is not on a stem that then has die-back from the cold.

One trick I learnt years ago - when pruning to an outside bud if there is another, bigger / more prominent "inner" bud a bit lower down which is not one you want to flourish, then just scrap it off with the secateurs' blade. Roses will sprout from pretty much anywhere, so no guarantees, but it does help you get control of the plant a bit :thumb: