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Roses: Not the how but the why

B3B3 Posts: 27,505
in Plants
I've asked a similar question before and I sort of understood the answers but to be honest, I'm still mystified.
If you plant a rose where another rose has been, you risk replant disease , but it's ok to plant a rose beside another. Why?

In London. Keen but lazy.
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  • FireFire Posts: 19,096
    edited February 2022
    I've tried planting a rose within two feet of another rose and still had problems. You can try digging out old soil over a wide area where a rose was and add new soil/manure, but that hasn't worked for me, to date. You can try digging a space and sinking a box like a wine box with new soil in it, so that the rose isn't contaminated by surrounding pathogen fungi Streptomyces and Nectriaceae

    Adding mycorrhizal fungi apparently can really help in early stage planting, in some cases. Bunny Guinness explains the workings (2021):







  • GardenerSuzeGardenerSuze Posts: 5,692
    It is known as rose sickness. For some reason the 2nd rose will grow but it will not really thrive.@Malorena if you read this I am sure you will be amongst the best forum members to ask. OnceI dug out a big hole  and swapped it for soil elsewhere, it did work. I believe that this problem can affect other plants like shrubs occasionally but these are only my thoughts.
    I have worked as a Gardener for 24 years. My latest garden is a new build garden on heavy clay.
  • B3B3 Posts: 27,505
    I'm more interested in the science than the how. I know not to try but I'm curious why.
    In London. Keen but lazy.
  • GardenerSuzeGardenerSuze Posts: 5,692
    Not sure it is completely understood .I can only comment from a gardeners perspective.
    I have worked as a Gardener for 24 years. My latest garden is a new build garden on heavy clay.
  • PianoplayerPianoplayer Posts: 624
    The underlying processes are still being studied, and not fully understood. This article from RHS explains that it is caused by the build-up of fungal pathogens that the mature roses can withstand but that new roses can't:
    https://www.rhs.org.uk/prevention-protection/replant-disease

    Here's a scientific paper from 2020:
    https://academic.oup.com/hr/article/doi/10.1038/s41438-020-00365-2/6445652?login=false

  • Joyce GoldenlilyJoyce Goldenlily Posts: 2,933
    I thought it was to do with the micro organisms in the soil which a rose needs. When a rose has been growing in the same place for a long time it depletes the ground from what it needs so if a new rose is planted in the same area, the new rose will have depleted soil to try and grow in. I can only presume roses growing in the same place for many years must create a symbiotic balance enabling them to continue growing, although some roses certainly do not seem to live for long in the same place.

    I expect there is an expert out there who can shoot this idea down in flames.
  • B3B3 Posts: 27,505
    @Pianoplayer. I will look at your links. Thank you
    In London. Keen but lazy.
  • FireFire Posts: 19,096
    This article says what Bunny says in the vid, but gives a few more details.

    "A working hypothesis is that the bacteria are attracted to the phenolic compounds that the roses excrete, and these bacteria then weaken the rose root in some way, which allows fungal entry."

    Apples and other fruit face the same problems.

    In the article it mentions sinking a large pot and growing a bare root in that for a few years until the soil pathogens in the surrounding soil have dissipated. It can take 3-5 years.

    https://www.telegraph.co.uk/gardening/problem-solving/could-reason-roses-arent-growing/
  • cmarkrcmarkr Posts: 142
    I'm listening to 'Soil' on audiobook at the moment and the author suggested that for apple replant disease, the symbiotic fungi that support the apple tree that died then seek to kill a new plant that gets planted in the new spot. It's unknown why but a hypothesis is that it prevents competition from seeds that land not far from the tree (preferring them to be spread wider through an animals digestive system) but there wasn't any clarity in the book on whether the mature tree needs to die first or if it's just at any point during the fungi's life (which makes more sense for the seed theory).
    Apples are in same family as Roses.
  • gjautosgjautos Posts: 429
    @B3 that's a really interesting question. I wonder how professional rose growers, DA for example, grow their roses. They must grow roses in the same spots after digging them up to sell as bare root. Yet they don't have a problem.
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