Rose black spots?

So I always thought any black coloured spots on rose leaves are black spots, as in the fungal infection. But recently I read somewhere that nutrient deficiencies can also result in black coloured spots on leaves and when I looked at the pictures they actually look very much like the ones I have on my plant- which I have been treating as fungal disease all this time - ie pruning them off and spraying. Have I been treating these spots the wrong way all this time? Also i always thought I’ve been overfeeding my roses so nutrient deficiency just doesn’t sound plausible- I’ve used fish blood bone, granule fertiliser, liquid fertiliser and rose tonic. I would have thought that’s pretty hardcore fertilising (probably over) and how could my roses still suffer from nutrient deficiency? 

Here are are some pictures of those black coloured spots


Posts

  • amancalledgeorgeamancalledgeorge South LondonPosts: 401
    That definitely is nothing fungal...if that was my plant I'd think this was maybe wildlife related...any birds pecking at leaves or any bugs. Your fertilisation regime sounds absolutely mad to me...yes roses are greedy but surely they just need a good mulch and some granular fertiliser early spring and mid summer. The leaves don't look too bad...so not sure if you're maybe overreacting in the pursuit of perfection. Happy to be corrected by any more experienced gardeners...
    To Plant a Garden is to Believe in Tomorrow
  • @amancalledgeorge Yes i have realised my fertilising regime is mental as I typed it up lol. I’m in my first year of rose growing so I’ll put that down to beginner’s (over) enthusiasm. 

    I grow mine in pots on a rooftop terrace and apart from seagulls I don’t get many birds or insects hanging around as it’s so high up. 

    So do blackspots need to have a tinge of yellow to be considered as true fungal ‘blackspots’?
  • amancalledgeorgeamancalledgeorge South LondonPosts: 401
    What makes me think it's not fungal is that they go through the leaves and make holes, most fungal infections only affect the surface of the leaf which is why they are treatable with sprays if one's inclined to use them. I can imagine growing them in pots you want to give them as much nutrition as you can. Just keep them well watered and step back from the fertiliser cupboard of yours  :D worth remembering that roses usually take at least a couple of years to look their best, so don't beat yourself too much if the leaves are not picture perfect, they'll only grow stronger with age. The longevity of roses is their nicest attribute, I have one that lived in a pot for at least ten years, and have now treated it to a spot in our front garden, feels like an old friend. 
    To Plant a Garden is to Believe in Tomorrow
  • Ha fair enough. Just out of interest how big is that pot of yours? 
  • MarlorenaMarlorena East AngliaPosts: 2,357
    ….sorry to butt in... what George said mainly, although I would say it's fungal.. a very minor issue at this stage...
    ...there is also some cercospora leaf spot - very low level..

    ..here are some [shocking] examples from my roses right now..  those new to roses panic at the sight of this and reach for sprays [keeping Bayer happy]… because they don't understand the life cycle of rose leaves, and how the foliage in Spring goes through what is called 'senescence' at this time of year - natural ageing - whereby the rose reduces the immune system of those leaves so they succumb to disease and fall off..  new growth should be arriving disease free, on good roses...  there is no need to reach for sprays... if the new foliage is also diseased then it would be time to consider a different variety..

    ...old leaves with various fungal issues... these leaves will be removed shortly and disposed of... but there's no need to be too fussy because it will return next year anyway..

    ..this is Cercospora Leaf Spot [Cercospora rosicola].. white eye black circle.. there is also some black spot [Diplocarpon rosae].. black spot with yellow.. and also some discolouration caused by mites under the leaves [small yellowy spots]..

    ..new healthy foliage on Munstead Wood.  you can see the old leaves senescing  below.. waiting to be removed.. full of black spot and cercospora...


    ...if this new foliage was also diseased I would get rid of this rose...



    ...your roses are a picture of health in the main..
  • amancalledgeorgeamancalledgeorge South LondonPosts: 401
    That was an education @Marlorena thanks for that. And more than happy to be corrected on the leaf disease ;) 
    To Plant a Garden is to Believe in Tomorrow
  • @Marlorena Thank you for ‘butting in’, I wanted to tag you actually but thought that might be too imposing of me given how many questions I’ve asked you in the past 😝 

    The new foliage seem to be disease free. It’s just the more mature leaf sets having some very small black spots. Most don’t have a yellow tinge at all, some do, but those I have removed for sure. Would you recommend removing the leaves that have thee spots on them (even if just a little bit)? I’m a bit obsessive with things so always trying to make my roses look perfectly spotless... 
  • MarlorenaMarlorena East AngliaPosts: 2,357
    ..that's ok, no problems and thank you...
    @celcius_kkw … no I wouldn't remove those with minor issues... roses do need as many leaves as possible to produce buds and blooms, so we should only be removing those which are the most unsightly.. they kind of reach a point of no return and we don't want to look at them.. I should be clear I don't blame anyone for spraying say in April or May time to keep their roses clean for the main flush ahead, but if mine got diseases that early I would reconsider the variety... 

    ... I wonder Adrian if you might need to adjust your expectations of roses a little bit...  accept some imperfections?.. I used to spray when I first started out but came to realise that this wasn't what I wanted to spend my time doing... but I know what it's like, I enjoy seeing perfect foliage too, and it still irritates me when I see blemishes.. but I have learned to turn a blind eye to most of it..


  • @Marlorena yes I do think I should grow to appreciate the odd spots. I guess I’m still on the process of getting used to what normality is like for roses. I’m learning by the day :) 


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