Which rose has been the worse Black Spot victim this year?

Discussion in 'Rosa (roses)' started by Weekend Gardener, Sep 26, 2005.

  1. Weekend Gardener

    Weekend Gardener Active Member 10 Years

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    Which rose has been the worse Black Spot victim this year? In British Columbia? I thought it would be informative to know. This year has been one of the better year for black spot in our garden. A number our roses seem to be unscathed at this point. But Moonstone and Gemini are outstandingly badly affected. How can it get any worse when there only a few leaves left on their poor skeletonised bushes?
     
  2. Ron B

    Ron B Paragon of Plants 10 Years

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    If might be more efficient to list those that were largely unaffected, as this problem is so pervasive among hybrid roses.
     
  3. angilbas

    angilbas Active Member

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    All of the roses in my garden had Black Spot, but 'Queen Elizabeth' and 'Mister Lincoln' were least affected. A 'Double Delight' succumbed; 'Love,' 'Peace' and 'Chicago Peace' were badly affected.


    -Tony
     
  4. Weekend Gardener

    Weekend Gardener Active Member 10 Years

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    End of the season. Time to reflect.
    Worse Blackspot magnets this year (total defoliation):
    - Abraham Darby (English)
    - Fire 'n Ice (Grandiflora)

    The least affected are (i.e. clean):
    - Golden Celebration (English)
    - Evelyn (English)
    - Frederic Mistral (HT - 'Romantica')
    - Felicia (Hybrid Musk)

    The rest of my 50 or so roses are somewhere in between.

    But overall, the first half of the season has been a good year with relatively clean roses. It only started to be a real problem at the end of August.
     
  5. westcoastgarden

    westcoastgarden Active Member

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    "Hot Chocolate" was a black spot magnet last summer.
     
  6. Ron B

    Ron B Paragon of Plants 10 Years

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    Maybe you should call it 'Dark Chocolate' then. Or maybe 'Chocolate Drops'.
     
  7. Dee M.

    Dee M. Active Member 10 Years

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    And yet 'Hot Cocoa' is resistant.
     
  8. westcoastgarden

    westcoastgarden Active Member

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    Very funny Ron - and sadly accurate.

    Dee - My mistake, I meant "Hot Cocoa". I bought it because of the unique colour and I collect plants that have chocolate in the name - not sure why because I don't particularly like chocolate....

    Anyway, "Hot Cocoa" pretty much defoliated for me last year. An Austin rose "Falstaff" four feet away and in the same conditions was clean all season. Another five feet away the ubiquitous "Pink Flower Carpet" (between my neighbour and I we have four) was its usual vigorous, clean self.
     
  9. Dee M.

    Dee M. Active Member 10 Years

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    Just goes to show how it varies with location and year. I have some friends who swear that 'Hot Cocoa' is very resistant, I don't grow it myself because I didn't like the color.
     
  10. Weekend Gardener

    Weekend Gardener Active Member 10 Years

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    Through the years of rose growing, I realise that another factor that affects black spot resistance is the maturity of the rose plant. This applies to the larger shrub roses. I have an Eglantyne whic was totally defoliated every year by blackspot for the first 3 years. Now that it is topping 6-8 feet in height, it has been the least affected of the roses in the garden. It makes sense, because the infection occurs from spores splashed on to healthy leaves, either from the soil or from lesions in affected leaves in the vicinity. The taller roses, therefore, would be the last to be affected - and, so, remain healthier longer.

    If you have any roses that you really want but appear to be affected, give it a chance and grow it on to maturity and find out how it fares then before taking out the shovel.
     
  11. Cathy W

    Cathy W Member

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    I’m in New England (Northeastern Massachusetts, on the seacoast). I’m not quite sure how our climates compare, but we had a veritable plague of black spot in this entire area last year.

    For the first time ever, I lost roses over the winter because they were so weakened. I went so far as to consult with the rose and garden supervisor for the Trustees of the Reservation (a nature group here in our state). They have been bequeathed behemoth estates and large open lands to preserve green space. They maintain these large estates and their gardens for people to tour and visit. I was sad but relieved to see that they were having just as terrible a time as we were having with it. I learned a lot about this plague hands on in one of the Trustees’ rose gardens. That’s why I love this forum, by the way – you get great advice from people who live it.

    Anyway, in addition to the usual hygiene and sanitation things and fungicides, he suggested I look into transpiration and also recommended that I apply dormant oil in the fall. As (bad) luck would have it, I became quite ill in the fall and did neither. I had to rely heavily on friends and family to put the roses to bed for the winter and not always with the same diligence that I would ordinarily use. Still, without them, I would have easily lost twice as many.

    I have six large rose beds and there were several roses that fared well and were scarcely affected or not affected at all. These included Mr. Lincoln, Mary Rose, Europeana, Smooth Lady, Millennium, JFK, Boule de Neige,and all four of my Queen Elizabeths. All of my climbers that are on a fence away from the main beds, and New Dawn, which is on a trellis and was playing footsies with a Chrysler Imperial that was horribly hit, were all spot free.

    Ironically, another Millennium I had in the next bed over from the unaffected one suffered terribly and we lost it. Go figure. But it just goes to show that regardless of whether the rose is supposed to be resistant or not, you can’t always count on it. I lost three Chrysler Imperials but the Queens, who are in the middle of the mess, did just fine, as did all of my hedge roses and simplicity roses.

    Our Lady of Guadalupe was the first to be hit and didn’t even make it to winter. She was infected over a weekend and from Friday to Monday the change was devestating. I saw a small spot on Friday morning and picked that one leaf off. But by Monday every leaf was heavily infected and they were more black and yellow than green. She just couldn’t recover from that.

    What I found fascinating is that the healthy roses were surrounded by literally dozens of others that had infections ranging from minimal to completely defoliated. There didn’t seem to be any rhyme nor reason for it. Despite all of our best efforts to stay on top of it, we lost almost a quarter of our roses this winter, and they were all the ones that had the most severe infection. We dug them out, cleaned out all the soil and replaced the loam and compost, and what a job that was. But the rose supervisor said that infected leaves and spores that might remain in the soil could bring it back with a vengeance and very quickly. We have already started preventive treatments with garlic oil and an Ortho product, alternating weeks.

    Has anyone tried transpiration? Any suggestions? Also, does anyone have a favorite dormant oil for over wintering? We have to be careful what we use and in what beds we use the various chemicals because we have a koi pond. I do use a lot of garlic spray, peppermint soap, Neem Oil, and Bt.

    Cathy W.
     

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