pink rose ID/what are these spots?

Discussion in 'Rosa (roses)' started by tash, May 14, 2008.

  1. tash

    tash Member

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    sorry if this is posted in the wrong place. useually I need help with houseplants, but we recently got a yard and it came with a rose in the front. It was growing ok, but had some issues with aphids/ants and some werid spotting. I still don't know what the spotting was but since getting rid of the aphids it seems better.


    here is a photo of the flower, it is a deep pink. and a photo of the aphids before I got rid of them. and a few of the spots.
     

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  2. Weekend Gardener

    Weekend Gardener Active Member 10 Years

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    The spots are blackspots, a fungal disease due to infection by Diplocarpon rosae. The spots appear in the warmer but wetter months - the fungus needs both warmth and moisture to germinate from the spores. The lesions first appear as black spots. These grow in size, and soon, a yellowing is seen in the surrounding leaf. The yellow area increase in size, and if there are several spots on the one leaflet, the yellow areas coalesce and the leaf drops off. With heavy infestation, all the leaves of the rose can drop off.

    It does not kill the rose, unless the rose is already weakened due to other reasons. But it is unsightly, and will interfere with flower production. In our garden, even completely defoliated rose bushes put on a second crop of fresh leaves later. And because the temperature would have cooled down by then, are less affected, allowing the rose to put on a second show.

    The spores are ubiquitous, and tend to be spread windborne. Once infected, there is very little that can be done to stop the leaves from falling off.

    It's not possible to avoid black spot altogether. You can reduce it's impact by implementing a preventative program. This should start with a thorough clean up in the fall or early winter. Clean up all the vegetative debris and detritus on the soil and throw them out (do not compost it at home). Pluck off any affected leaves still on the dormant plant (some rosarians recommend removing off all the leaves of overwintering roses). Remove any weak or damaged canes. Spray with lime-sulfur dormant spray. Through out the growing season, pay careful attention to removing all the leaves and vegetative materials that fall off and drop on to the ground. Use a layer of fresh mulch to keep the spores in the ground. Remove all the affected leaves at the earliest sign of disease (once the disease has taken hold, this would be an impractical method).

    There are fungicide sprays that can be used on a program of regular spraying to reduce the impact of the disease, but none of these are available in garden retail stores in Canada. There has been attempts to control the disease with other more benign chemical agents - e.g. Sodium bicarbonate. This works by raising the pH on the surface of the leaf when it gets wet. However, one would need to spray very frequently to maintain this - a good shower or drizzle would probably be enough to wash off the protective effect. There are some who suggest that Potassium Bicarbonate works better.

    Healthy vigorous plants appear to be more resistant to black spot. It may be that healthy plants have a thicker and more protective cuticle layer. So, keep your roses healthy by soil improvement, adequate feeding and consistent watering.

    One more thing one can do is that if you are considering replacing any of your roses, pick a selection that is more black spot resistant.
     
  3. tash

    tash Member

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    Thank you!

    I actually live in a townhouse, but we can do whatever with our gardens as long as it isnt edible. however we do have to put up a border of soem sort so that the lawn maintence people don't mow our plants down. they ran over a small azalia (sp?) I bought earlier this spring. it looks ok... just flat... but since then I put in some bricks as a border :D
    anyway back on topic....

    people move in/out here about every 2-3 years on avrage. I am guessing this rose was planted by the person before the person before me. it seems to have been neglected for a couple of years. it needs some major pruneing. I sprayed it with insecticidal soap and then with a strong jet of water the next day to get rid of the aphids (then more soap since I probably washed it all off). the water seemed to knock off a lot of the leaves, especilly the yellow ones. it looks a lot better now... if a little thinner. I plan on doing a lot of cutting back in the fall and see what happens next year. I guess I will throw the clippings in the trash then....
    I also bought some rose food and poured that around the base of the plant. the growth since then seems better. I don't know if it was the food or the wearther.....

    I am kinda using this as a "practice rose" since we plan on buying a house in a couple of years. then I can have a real rose garden. I figure if I can bring this poor neglected rose back then I should be able to do better with a fresh garden and new roses :D
     
  4. tash

    tash Member

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    still trying to find out what this one is.... does anyone think this might be it?
    http://www.helpmefind.com/rose/pl.php?n=601

    the flowers are about 2" and it has a very very mild fruity fragrence. I can try to get more photos......
     
  5. joclyn

    joclyn Rising Contributor

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    you need to treat with a fungicide that is specifically for blackspot on roses. remove all affected leaves when they fall to the ground - the spores will lay on the soil and cause problems next year. you can also remove affected leaves off the bush too (before they fall).
     
  6. Weekend Gardener

    Weekend Gardener Active Member 10 Years

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    There is no effective fungicide against black spot available in Canada for residential use.
     
  7. joclyn

    joclyn Rising Contributor

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    tash is in the us, so should be able to get something at the local home depot or lowes.

    we've also had the most effective fungicides taken off the market in recent years...still there ARE a couple of products that, if not completely rid the plant of the fungus, really do put it in decent check - you have to be vigilent with treating though.
     
  8. Weekend Gardener

    Weekend Gardener Active Member 10 Years

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    You are right, Joclyn.

    In which case, this Virginia Tech corporative extension web page also give a list of possible effective chemicals. I am not thoroughly familiar with a complete season long program of spraying - only limited targeted spraying with whatever is available. This currently means none of the chemicals available on that list as the last one, Funginex, have been off retail shelves for over a year. Others did not even make it to the shelves.

    If you are considering going this route, you need to make an informed choice about what you are intending to use or if you want to use sprays at all, which means learning as much as you can about the spray you are thinking of using. A helpful web site Cornell University extension website provides reasonably balanced and well referenced information on most products used in the industry. I won't use most of the fungicides on the above list based on information available, but others find acceptable with precautions.
     
  9. joclyn

    joclyn Rising Contributor

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    other than putting lime down on the soil (which doesn't actually do all that much good) there is no 'natural' treatment for the black spot fungus that i'm aware of. so using a chemical is the only way to go if you don't want to lose the whole bush.

    i've only used products that are specifically for that particular item - never anything that treats multiple issues (1 because there is no other issue present and 2) because i really would rather not use chemicals at all and want to limit any residual damage caused by having to use something).

    if anyone knows of a natural treatment that actually kills the spores, please let me know as i'd really rather not use the chemicals. in fact, i'd really love to be able to use something natural. the first product i'd used was taken off the market (which worked wonderfully) and the second thing i'd gotten didn't work as well (different chemical).

    we've had a lot of rain lately, so it's really bad this year...and showing much earlier than it usually does. the one bush i have is almost completely covered in it already - i've never seen it so bad so early!
     
  10. tash

    tash Member

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    I really prefer to go as natural as possible. and the thought of using something that may go off the market is just plain scary :eek: especilly since I have a toddler who loves to help me in the garden....

    so far the spray I did for the aphids seems to have knocked most of the black spoted leaves off the bush. today I put down some more mulch (part of it got washed away from all the rain and the fact that the gutter leaks, I told the complex office but I don't know if they actually fixed it, they said they did...). I go out about every day and prune off any leaves that have significant black spot on them. most seem much better now. I also tied up one cane that was getting really close to the ground with all the flowers on it. this fall I plan to do some major pruning, then take up all the mulch and get rid of it before putting down more for the winter.


    here is a photo of what it looked like before I did the spraying/pruning. I will try to get a photo of it now tomorrow...

    and another photo of a flower... still trying to figure out what it is. it appears to be own root as there are canes comeing from sevral places in the ground.
     

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  11. Weekend Gardener

    Weekend Gardener Active Member 10 Years

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    That's a better picture, but I still can't put a name to it.

    Your rose bush looks rather "crowded". Are there any dead, weak or old unproductive canes that you can prune off. Taking those off should improve the overall health of the bush and increase resistance to disease.
     
  12. tash

    tash Member

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    yeah, like I said it has been neglected plus whoever planted it put it really really close to the house too. I finally bought some loppers and took off anything that looked dead. since I knocked off a lot of leaves I don't want to take too much off of it for now but I am already planning cuts for fall...

    here is a photo of the whole bush from today. it lost a lot of leaves when I sprayed it with the hose to get rid of the aphids. most of them seemed to have some degree of blackspot. you can see the one I tied up too. It was touching the ground.

    (my lobella is doing quite well though)

    the first photo of the whole bush was taken on may 5th, this one was taken today (may 25th)
     

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  13. Weekend Gardener

    Weekend Gardener Active Member 10 Years

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    You have done a great job with your pruners. In my books, those small, twiggy, weak laterals should also be taken off. You should see new shoots starting to emerge in the next few weeks. This seems to be a reasonably predictable outcome of a good round of pruning.
     
  14. tash

    tash Member

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    thanks. I pruned off more today and did some dead heading. there already are a lot of new shoots comeing out from the pruning I did a couple weeks ago. it is looking so much better but I have to keep telling my husband that next year it will look even better :D
     
  15. Weekend Gardener

    Weekend Gardener Active Member 10 Years

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    Tash,
    It sounds like you don't have to wait till next year. That rose bush will already look much better in 2 month's time.

    Are you fertilising it?
     
  16. tash

    tash Member

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    yeah, I gave it some rose food a while back.... maybe April? I think the box said to do it again in July......

    I think it looks a lot better now. there are tons of new leaves. but it is still rather lankey. :)
     
  17. nic

    nic Active Member 10 Years

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    Rosa gallica? Not sure about the leaf, though. How thorny is it?
     
  18. joclyn

    joclyn Rising Contributor

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    do a heavy pruning in the fall...or you could wait until early spring next year (around st pat's day). that should help it grow more bushy next year.

    very pretty color!! i have no idea on which one it is though.
     
  19. lorax

    lorax Rising Contributor 10 Years

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    I'd lean towards Gallica as well... It reminds me of the wild doubles I used to have in Canada.
     

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