This topic contains 1 reply, has 2 voices, and was last updated by  Bob 1 week, 5 days ago.

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  • #22091
     Koen 
    Moderator
    @khurtekant
    Topics: 28
    Replies: 16

    I was reading an article about peony diseases today and it happened to mention (partial) resistance to botrytis (grey mould). This is an interesting topic as I would very much like to incorporate some resistance into some of my seedlings. After all, there’s no cheaper (and more environmentally friendly) way to control that disease than by growing those that are not susceptible to it. The article noted a research project whereby over a hundred cultivars were tested and grouped according to their (partial) resistance. Unfortunately the research is old (1930) and thus contains mostly lactiflora cultivars that are no longer grown. Besides that, the fact that Sarah Bernhardt was included in the group ‘fully resistant’ means that we have to take the results with a grain of salt as Sarah surely isn’t, speaking from personal experience.

    It noted that intersectional cultivars are more or less resistant, something which I’ve also noted, good for gardens but for cutflowers they are far from perfect with their shorter vase life.

    In a few years time I’ll know somewhat better what cultivars are able to cope with botrytis as most to all of my cultivars are now growing at another organic nursery that doesn’t use any fungicides. But for now I’ll just have to guess which ones are better at it. I’d be most interested to know whether any of the species show some resistance to it (or to other diseases). I guess there might be some correlation with foliage remaining green long into the Autumn. But of course the resistance of the foliage doesn’t tell us necessary if the flowers are also resistant.

    Thus if there would be anyone having some experience as to what are the best varieties in this respect, I’d very much like to hear about it?

    all the best,

    koen hurtekant
    belgium

    Growing peonies for cutflowers in Belgium. Also hybridizing them.

  • #22118
     Bob 
    Participant
    @bobjohnson
    Topics: 3
    Replies: 26

    Koen,

    I don’t get too much botrytis at my home garden – our volcanic sandy soils drain all too well, and our desert climate is naturally dry.  But I do get some of it sometimes, and I see it on certain seedlings at the nursery sometimes as well.

    Really, the only conclusion I’ve been able to draw is that plants which grow in a particularly vigorous manner in spring are often the ones which are most susceptible.  This seems to have to do with the rapid rate with which the cells expand on vigorous varieties, and varieties with particularly thick stems.

    One example are seedlings I call “One Stem Wonders”.  These are plants with large root systems, but which tend to throw up just one single enormous stem, along with a massive sized bud.  I’ve gotten 3 or 4 of these over the years, but never been able to keep a single one of them past their first mature year.  Once dug and divided and kept for further evaluation, every single one of them has died from stem botrytis in spring, before they ever had a chance to grow into a plant.  And this is at the nursery, where carry out a well thought out and responsible spray program.

    One hates to think that vigor is a negative quality, so perhaps it has something to do with the relative toughness or thickness of the cell walls which make up the exterior of the stems ?  A measure which may have something to do with the speed of cell expansion ?

    These are just antidotal observations of course, but I know that I tend to pay particular attention to vigorous varieties which really rocket up out of the ground in spring.

    Bob Johnson

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