Black dots on roses

Discussion in 'Rosa (roses)' started by jreidsma, Oct 3, 2009.

  1. jreidsma

    jreidsma Active Member

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    In front of my house I have 4 roses (I don't know what type they are) and they have been there for 5+ years. But in the last month the smallest one got a black dot on a leaf and after a couple days all the plants had it on almost all of their leaves. Is there anything I can do to save them from this? I heard that watering from the bottom and not getting the leaves wet would help with not spreading it. The dots are only on the top of the leaves and they turn yellow and fall off after a day or two.
     
  2. lily

    lily Active Member 10 Years

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  3. joclyn

    joclyn Rising Contributor

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    definitely sounds like black spot - which is a fungal infection. it happens when it's very rainy and the roses don't have sufficient time to dry out - and it can spread quickly.

    there are products on the market to treat it - use something by ortho as theirs are most effective. also, remove any infected leaves - completely. do not allow the leaves to lay on/stay on the ground around the bushes as that will allow the spores to get to the soil and reinfect next season. you can also remove a thin layer of soil (to get rid of any spores) and then replace it with fresh soil/compost.

    this is something that you 'control' rather than get rid of. some varieties are prone to it and others never get it (i have one bush in the row that never has it; yet, all the rest do - even the one that has canes hanging right above it).

    treat now with the spray and then, in spring, as soon as you see even a touch of infection, get the bushes sprayed and follow package directions faithfully (barring rain interferring) and it shouldn't get out of control. it's something that will need to be done all summer long usually.
     
  4. jreidsma

    jreidsma Active Member

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    I might not be able to put anything on them soon. It has been raining for a week and still hasnt stopped. And its supposed to snow alittle in a week...... maby I will be able to do it soon.
     
  5. joclyn

    joclyn Rising Contributor

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    well, i wouldn't really worry all that much at the moment. with winter weather coming in, the bushes are going into dormant phase, so, don't fret over it.

    just stock up on something so you have it at the ready in spring time when the leaves start budding out again. you can spray them as soon as they're about an inch long (as preventative) and then continue periodically spraying throughout the season.

    that's what i usually do.
     
  6. jreidsma

    jreidsma Active Member

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    Im still going to put the stuff on them in the begining of early spring or when ever they start to make leaves, but all but one of the rose plants seem to be fighting it off. They were covered completely in deseased leaves but now there are only about 10-25% of the leaves infected now. Infact the one plant is now flowering again.
     
  7. lily

    lily Active Member 10 Years

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    I was also told to be sure to pick up and 'get rid of' any infected leaf parts.
     
  8. 2annbrow

    2annbrow Active Member

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    This is really common here in Oregon, and everyone deals with it the in ways you've all described. But one other thing most folks do is to wipe or dip the blades or pruners in a peroxide solution before moving from one plant to another, to minimize the spread of the blackspot.
     
  9. Ron B

    Ron B Esteemed Contributor 10 Years

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    It is probably not necessary to sterilize pruning tools to prevent transmission of
    soil- or air-borne pathogens. These diseases, generally bacterial or fungal in nature, are more likely to be
    transferred by your hands and clothing than by your pruning tools. Obviously you should avoid being a
    direct vector in disease transmission, but you will probably have better success in controlling these
    diseases through preventative landscape management practices (e.g. pruning diseased parts, disposal of
    contaminated leaf litter, and use of disease-free compost and mulch)

    http://www.puyallup.wsu.edu/~linda chalker-scott/FactSheets/Pruning.pdf
     
  10. joclyn

    joclyn Rising Contributor

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    what he said!! :)
     
  11. 2annbrow

    2annbrow Active Member

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    Ron - Thanks for the good info. Now, if I could only get the deer to sterilize their noses as they move from rose to rose, eating all my flower buds . . .
     

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