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Roses grown in no-spray gardens

May 3, 2015

I'm interested in hearing from experienced rose gardeners about disease patterns they see with young rose plants growing in a no-spray garden.

From what I've read at this forum and elsewhere, it seems that if rose plants are 'allowed' to get BS, Powdery Mildew, etc. as youngsters, most will become more resistant to these fungal issues as they get older.

I'm sure there are some plants that will always have more problems than others, but would you say that many/most antique roses will outgrow the fungal stuff if their immune systems are exposed to it at any early age?

Would you say that young roses with BS or PM will mostly 'grow out of it' by a certain age? If so, is there a pattern that you've recognized in terms of how long it takes a rose's immune system to mature in a no-spray situation? Are certain classes slower or quicker with this process?

Thanks for any insights you can share,


Comments (29)

  • seil zone 6b MI

    I think there are some roses that can become less susceptible as they mature but I don't think they ever completely grow out of it. If you think about it a newly planted rose doesn't have the root base or structure in place yet to fight off an attack the way a mature rose would. That's why I feel it's not a good idea to judge any rose on it's first couple of seasons. You need to wait to see what a rose does in it's stride to decide if it's good or not. On the other hand if it's susceptible to BS in your area when it's young the tendency may lessen with age but I doubt it would ever go away completely. So it may do quite well for most of the time but if weather conditions are just right and the pressure is high it will probably still get it. Maybe to a lesser degree but will have some none the less. And since there are MANY different strains of black spot out there a rose may not get one kind but may be very likely to get another. So what a rose does in one place may be totally different from what it does in another. I've heard people swear that Angel Face was healthy for them but here she is the world's worst black spot magnet!

  • catspa_NoCA_Z9_Sunset14

    Well, PM is always a problem here. There are many roses that suffer from it when young, especially in pots (e.g., Florence Bowers', Le Pactole), but then suffer from it less (only a bit in the worst part of the year for that, for example -- a lot of Chinas do that), or not at all, once fully established in the ground. Some others, Gilbert Nabonnand to name one, never develop resistance; that one looked like frost in August every year for more than 8 years until I finally couldn't take it anymore (and finally realized he was never going to "get over it"!).

    BS is only a problem here in late winter/early spring; for the rest of the year, it's not a problem at all, even for very susceptible roses (Pernetiana HTs, for example). The ones that do get BS, however, seem to get it no matter how mature they are.

  • AquaEyes 7a NJ

    What I've noticed is that the roses don't necessarily become "immune" or "more immune" to blackspot as much as they simply grow more vigorously as they mature. So when they lose some leaves to blackspot, the more mature roses will simply grow them back faster than the babies.



  • mad_gallica

    There does seem to be a connection between the ability of a rose to resist disease, and the establishment of the root system, particularly in the case of mildew in drought prone areas. However, IME, except for extremely young roses (less than a year old cuttings) roses don't grow out of anything. In fact, the opposite tends to be more true. Over time, more varieties of blackspot find the rose garden, and previously resistant roses start having problems.

  • dublinbay z6 (KS)

    I'm with the others. It isn't like being exposed to childhood diseases and then being immune for the rest of your life because you have the anti-bodies in you now. Young roses are sometimes a bit wimpy and underdeveloped, so they can be (if weather conditions are right) more susceptible to BS, but as they grow good root systems and become much more vigorous, they MAY not be as susceptibles--but there are no guarantees, as far as roses are concerned.

    Keep in mind that blackspot has to do with temperatures--say, 75 to 85 degrees or thereabouts. That is when the BS spores can multiply and spread like crazy sometimes. But if the temps are 60 degrees or 95 degrees and it is rather dry out there, spores rarely develop in any significant numbers, so if you plant a wimpish plant in 60 degrees and dry conditions, it may not have any BS problems, but that same plant planted in 80 degrees and moist, humid air, it may develop BS problems. In the really hot regions--with temps in the high 90s to 100s, your roses won't have many BS problems at all--too hot for BS spores to develop usually.

    It is not about developing immunities (anti-bodies) to BS disease.


  • henry_kuska

    I assume that the original inquiry was about whether those who grow roses in no spray gardens observe less blackspot with time, yet many of the people that replied are people who spray. I feel that the distinction is important as my experience and reading indicates that in about 5 years Nature controls blackspot on roses with friendly fungi and the internal immune system of the plant itself. Please note the "control" means just that - control, not "eliminates completely". In my previous 1000 roses no spray garden, I would observe some blackspot in the fall. I interpret this as part of natures way of shutting down the roses for my zone 5 winter.


    Also see:


    In the above link the age related resistance link no longer works. Here is the new one:


    The above age related resistance paper has been cited by 45 newer scientific papers.


  • Vicissitudezz

    Thanks for the input so far. From what I have read, all plants have an innate immune system that they inherit from their parents, and uses specific resistance genes geared to specific pathogens that the plants have evolved over generations.

    Plants also have a sort of adaptive immune system that may allow them to combat unfamiliar bad guys... presumably this will only work if the plant is already pretty healthy, and if the plant's environment isn't too stressful.

    Almost all of my named and mystery roses are very young (and then there is my unexpectedly large crop of seedlings from this year). I'm not especially worried about if the esthetics of whether they get a little PM or BS. I'm just wondering what to expect from their ability to adapt to their environment as they mature.



  • jerijen

    But it is also regional. Someone mentioned, for instance, that 'G. Nabonnand' was always covered with mildew. Whereas I, in "mildew central" have never, EVER seen mildew on that rose. ('Mme. Lambard,' OTOH, is a different story, and is often troubled by mildew.)

  • Vicissitudezz

    Thanks, henry_kuska... the first link seems to be the kind of info I'm looking for, but I'm sure the others will be of interest. I guess I didn't phrase my question well.

    Since I've just started to grow roses in the last year, and since many of my plants are from cuttings I took (or from young plants or cuttings I got from generous gardeners (not the Austin rose), I'm hoping to benefit from the experience of other no-spray gardeners.

    I especially liked a comment I saw early in the first link about how roses develop their own protective biodiversity; that chimes with what I'm hoping will happen with my roses, and what I think I'm seeing with other types of plants I have a bit more experience with.

    Best regards,


  • catspa_NoCA_Z9_Sunset14

    Or perhaps the clone, Jeri? I often wonder if my particular G. Nabonnand might have had some sort of record-breaking mildew mutation -- have never seen worse on any rose, even compared to my neighbor's Dorothy Perkins that peeks over the fence. Mme. Lambard mildewed badly here, too, unfortunately...and Safrano...

  • nikthegreek

    My experience does not support any hypothesis that 'allowing' a plant to 'acquire' powdery mildew when young will enhance its defensive mechanism when mature. On the contrary, plants highly susceptible to PM when young and which get affected by the fungus for a long period during their growing seasons will be in general be compromised as they mature due to their growth capability being affected by the fungal infliction. Cultural practices do have an effect on a plant's mildew resistance (they can even turn a somewhat susceptible plant to a highly susceptible one - just try the water stress method...) but this is unrelated to the original question. Of course a matureh well grown plant will present a more healthy picture even if afflicted by the fungus but I have no reason to attribute this to any acquired immunity rather than other factors (e.g. robustness coming with maturity, potential for better access to water, ratio of older shoots not susceptible to the fungus over younger susceptible ones etc). In addition, with regards to PM, I have not noticed any phenomenon supporting the idea that adaptations of the micro-environment itself creates conditions which effect natural control of the disease*. Any such phenomenon, even if exists, is, in my case, subtle enough to be masked by other factors (such as variations to the climatic conditions year on year). I'm sure that if someone somehere sometime has published a paper which obliquely may point to facts which might, under conditions, indirectly support the reverse hypothesis, our resident discriminatory and highly selective research digger is uniquely enabled and willing to dig it out and present it to us as if it were the last and only word in scientific research on the matter and potentially universally applicable.

    *PS. Natural adaptations (be them evolutionary, environmental or other) have one and only purpose. For the living organism(s) in question to extend their life as long as possible and at least until able to reproduce under adverse conditions. This does not necessarily fit with our ideas of the purpose of a plant (be it for decoration or for consumption). It does not also necessarily fit with our idea about which organism is more or less important, which is 'good' and which is 'bad'. In a natural environment most of the roses we cherish and most of the plant varieties we depend on for food would not exist. Just a bit of food for thought..

  • Vicissitudezz

    Hi Jeri-

    Location, location, location is certainly important. I understand that plant immunology hinges on the interactions between the plant, the pathogens and the specific environment (what I've heard called the disease triangle).

    The link to subk3's thread about plants improving with maturity is helpful- she asked what I should have asked, and if I were clever, I would have found that discussion, and wouldn't have started this new thread less than 2 years later... (Although it's quite possible that I did read it in the meantime, found it influential, and then forgot where I'd encountered the info.)



  • jerijen

    Well, some roses DO improve with maturity ('Le Pactole' sure did!) but many don't. We grew 'Old Blush' for years before admitting that, as great as it is in many places, it is a pile of mildewy pooh here. And at that, I know it still matters where you are and what your conditions are. So, I try really to give suggestions only to people in conditions similar to mine. And even then . . .

  • AquaEyes 7a NJ

    We must remember that attaining "maturity" includes more than what we see above the soil line. Mature roses will have deeper roots for accessing water and nutrients, and better established relationships with organisms within the soil, making them better able to shrug things off. It might appear to our eyes that the mature rose has developed resistance to a pathogen which once affected it in its youth, when in reality, it may have finally had its roots colonized by beneficial fungi which provide natural chemical assistance to ward off disease. Of course, there will always be some roses that are simply forever disease-ridden in a given area, so what I said doesn't mean that ALL roses will eventually shrug off blackspot or mildew as they mature.



  • Vicissitudezz

    Hi Christopher- you make a useful distinction between disease resistance and disease tolerance. I'm no botanist or plant pathologist, but I think all plants must be resistant to some bacteria/fungi/viruses/nematodes, etc. while at the same time being susceptible to others. Hopefully, a healthy plant can tolerate the pathogens it can't fend off.

    Certainly, there are some varieties (or bad specimens of varieties- maybe catspa's 'G Nabonnand'?) that will always have problems in certain environments when infected with certain fungi, viruses, or whatever. Those varieties must do well somewhere, though, or they wouldn't have made it to adulthood or been propagated as plants in various locales.

    The roses I'm mostly interested in are the older varieties that have survived because they do tolerate a variety of different environments and levels of disease pressure, but I don't think any rose will be great everywhere- or great anywhere for all 365/6 days of the year...



  • henry_kuska

    The following was stated: "My experience does not support any hypothesis that 'allowing' a plant to 'acquire' powdery mildew when young will enhance its defensive mechanism when mature."

    H. Kuska comment. In the general case for plants, this is called Systemic Acquired Resistance.


    Also, please read the first paragraph of the Introduction section of the following full paper.


    H. Kuska comment: salicylic acid has been determined to be one of the major components in the triggering of the systemic acquired resistance of the plant immune system.


  • nikthegreek

    Pls. parse my first sentence properly (there are some definite subjects and objects, to use grammatical terms) and read my last sentence. Also please read the postscript and make reasonable inferences in the context of this forum.


  • henry_kuska

    " I have only gotten one seedling from YBR without mildew issues. Fortunately most grow out of it."



    "Banksiae seedlings seem addicted to mildew until they mature sufficiently for their immune systems to function properly."



    " It required more than its first year for Cal Poly X Basye's 86-3 to outgrow its addiction to mildew. Even during the cool, damp periods, the foliage remained clean. As a young seedling, I had some serious doubts about this one's success. The mildew was SO bad."



  • nikthegreek

    So, the well known fact stemming out of experience (which both I and other posters aknowledged) of some roses appearing to outgrow, to a degree, their (usually mild) PM tendencies, you atrribute to SAR and not to other factors some of which were well exposed by me and other posters. Based on what exactly? Would the banksiae seedlings, for example, not exhibit PM resistance when more mature if they were not exposed to PM as seedlings? Based on what conclusive evidence should we make that inference? And what do seedlings have to do with the OPs question? QED, with regards to your attitude (again).

    My experience is that roses that are BADLY afflicted when young (no idea about seedlings) very rarely grow out of it. So rarely that for practical reasons (i.e. garden performance) they usually are hopeless cases. Exceptions are just exceptions, serving no real practical purpose. It is the mild cases which sometimes seem to get better with maturity (and can often easily relapse if cultural conditions deteriorate or PM pressure becomes high). I can believe anything (including that SAR is a major factor in PM resistance) but I've yet to see anything (either experience or science based) which unequivocally supports that view. This might well change in the future but I, as opposed to you, keep my eyes and ears open to anything rather than fight a cause one way or the other. Producing selective scientific (or worse anecdotal) evidence just to support one's preconceptions or wishful thinking is the bane of science in my view. In the meantime, I have bad PM cases this year (in an area where PM appears every single year in spring and fall) on roses that are mature and have never exhibited this tendency before. I attribute this to greatly increased PM pressure this year (an observation which is supported by my local agricultural office warnings to farmers). Enough said on my part, I know it's a waste of time.

  • dublinbay z6 (KS)

    I think that is what many of us have been saying. It is not exposure when young that causes a rose to "acquire" an immunity of the disease, but simply the development and maturity of the plant that causes the resistance to work more effectively--especially if the plant was not overly healthy in the beginning. But as others have pointed out, that is only true of "some" roses--though in general a sickly plant will not fend off disease as efficiently as a vigorous, healthy, well-developed specimen will.


  • henry_kuska

    The following was stated: "So, the well known fact stemming out of experience (which both I and other posters aknowledged) of some roses appearing to outgrow, to a degree, their (usually mild) PM tendencies, you atrribute to SAR and not to other factors some of which were well exposed by me and other posters. "

    H. Kuska comment: In my original post I stated: "I feel that the distinction is important as my experience and reading indicates that in about 5 years Nature controls blackspot on roses with friendly fungi and the internal immune system of the plant itself." Please notice that "with friendly fungi" was included by me in that statement.


    The question was asked: "And what do seedlings have to do with the OPs question? "

    H.Kuska comment: The original poster in a follow up post stated: "Almost all of my named and mystery roses are very young (and then there is my unexpectedly large crop of seedlings from this year). I'm not especially worried about if the esthetics of whether they get a little PM or BS. I'm just wondering what to expect from their ability to adapt to their environment as they mature."


    H.Kuska comment: I presented general information about what is known about the immune systems of plants at three levels, the first being a general scientific dictionary article, the second being the introduction to a reviewed article (which of course had to be approved by the reviewers and the editor), and the third being a general Google Scholar search.

    In reaction to a comment, I then presented 3 comments specific to the ageing of young roses. I could of presented more, but anyone can go to the Rose Hybridizers web page for further examples. Of course anyone can present their experiences (are they experiences in a no spray garden - please note the title of the thread). This is a forum.

  • AquaEyes 7a NJ

    For some, the prospect of a debate is more enticing than the subject matter.



  • henry_kuska

    The readers may be interested in the following information from a Rose Hybridizers thread:


    I particularly recommend the link posted on May 31, 2008 to an article posted by John Starnes in Help-Me-Find.

  • nikthegreek

    PM is rarely devasting to the extent of eradicating the hosting plants. Natural equilibrium may be reached in a garden environment (although this is quite difficult given the introduced or hybrid nature of many a garden plant) but this does NOT mean the affected plants appearance make them garden worthy. From nature's point of view this is OK, from the gardener's or producer's point of view this may not be good enough. Ths is a very important distinction to make. From nature's point of view it is OK if I die prematurely of a disease as long as not all human race is eradicated, from my point of view it is not OK and I'll take drugs to try and prevent this from happening.

    With regards to rose PM the best defensive method in my point of view and on my experience is to get rid of plants which exhibit intolerably great PM afflictions intolerably often. For the rest, good cultural practices (and that includes NOT trying to eradicate all non-rose living life off one's garden) can make the difference. I don't have a monoculture, I grow native plants together with my roses, fruit trees and other garden plants. I do not use herbicides and only use bio approved methods to control insects and mites whenever and if it is required. I do spray occasionally with fungicides but not preventively, only occasionally and localized whenever I feel enough is enough (which usually means 2-4 times a year and only on selected plants). I recycle most garden debris, I do not remove fallen sick leaves. I'm open to any mild or natural method for control as long as it is effective in the long term and as long as it is practical in the scale of my garden. I'm trying AQ10 (containing a mycoparasitic fungus attacking oidium sp. - grapevine PM) on my grapevines and I intend to try it on some roses too. I still believe that cherrypicking, selectively quoting 'evidence' without putting them into context and without drawing logical and practical conclusions (this is a gardening forum not a scientific one and I would expect any quotations are accompanied by sensible comments and not paraded in sequence uncommented on) and moving the goalpoasts in 'arguments' just to fight one's holly cause is totally counter-productive and insulting to readers' intelligence. 'Edited and peer reviewed' right, as if this means something more than an assurance that the writer has followed correct scientific procedure in producing the paper.

  • henry_kuska

    In the first comment in this thread that a certain poster has made the following appeared:

    " I'm sure that if someone somehere sometime has published a paper which obliquely may point to facts which might, under conditions, indirectly support the reverse hypothesis, our resident discriminatory and highly selective research digger is uniquely enabled and willing to dig it out and present it to us as if it were the last and only word in scientific research on the matter and potentially universally applicable."


    H.Kuska comment. The above comment needs no reply. The thread speaks for itself.


    Thank you Virginia (vmr423(Zone 8b, SC - the person who originated the thread) for bringing up this topic and for your additional comments. It appears from your comments that you already had done some serious reading.

    I hope this thread serves as an example that our understanding of plant behavior is still evolving, and that those who grow ornamental plants will encourage their children, grandchildren, nieces, nephews etc. to consider a career in agriculture research.

  • Rosefolly

    There are a lot of romantic ideas about rose health. I very much wish that some of them were true. Here are my own thoughts on the matter.

    Roses under stress are more susceptible to disease than that same cultivar would be in more ideal conditions. A young rose that first year or two or three might not yet have grown a root system that can reach water efficiently. Just as important, it might not yet have established an extensive partnership with mycorrhizal fungi in the soil. That rose will be more robust once it has accomplished these tasks, and we should see less disease because it is stronger. But it will never be more disease resistant than is innate for that particular cultivar. Think of an analogy in people. Take someone who is born shy. Raised thoughtfully, he can become more confident and more expressive, and even more comfortable with other people. Eventually it may not show, but in his heart he will always be that shy kid. So it is with roses. In the best circumstances, they will realize the most disease resistance they are capable of, but they will never outgrow disease vulnerability that is built into them.

    The reverse is true as well. I have had roses that got no disease for several years then suddenly did. Sometimes it is a permanent thing and they go on getting BS/PM/rust, and sometimes it is just the conditions of that particular year favoring disease.

    If you do not plan to spray, you will be a happier gardener if you choose your roses from among the varieties that tend to be highly disease resistant in your area. They will get disease occasionally, but most years, not much. And it does need to be your own area. For example, Jerijen and I both live in California with a Mediterranean climate but are a couple hundred miles apart. She has heavy fog influence and for me fog is occasional. Our temperatures are different, too. We both see powdery mildew and rust, but not necessarily on the same roses.

    This does not mean that you must never grow a rose that gets disease. Deuil du Docteur Reynaud gets powdery mildew and rust starting midsummer every year. I can't even pronounce it but don't care because I just love it. Huge, gorgeous, fragrant roses and it reblooms well, with a huge flush in the fall when it is the star of the front garden. You can pick one or two or three of such roses and have a beautiful garden. You just don't want all of them to be like this!


  • jjpeace (zone 5b Canada)

    I agree with everyone! I think that you first start by choosing varieties that are more disease resistant to your area. But in the end you have to love it too. I have chosen roses that I know are not very healthy in my zone but I just love the flowers. I started this year to rake off "obsessively" all the old leaves from last year and hope that will reduce or slow down the problem. But for me since I live in colder zone, by the time my roses are defoliated, it is already autumn's time and most plants drop their leaves anyways.

  • odinthor

    My experience is absolutely and unquestionably consonant with biodiversity controlling mildew and rust within 5 years. (Black spot is not a problem in my area, coastal Orange County, California.) For one compelling instance: That notorious ruster 'Fashion' (with which I have had decades of experience) became all but rust-free after 3-4 years of not being sprayed. Anyone who has grown 'Fashion' knows that this is nothing short of miraculous. A very few varieties (for instance, 'Yolande d'Aragon') will go through an annual period of rust, then drop their leaves and bounce back with new leaves that are rust-free for the rest of the year. Also, on another topic mentioned in this thread: Young plants that mildew and rust most frequently grow out of it as they mature. The problem is not mildew and rust. The problem is people fussing about them.

  • Rosefolly

    I can agree that a biodiverse garden is going to be healthier than a monoculture for many reasons. However my own garden is quite diverse and I still get some PM and rust on susceptible cultivars. Most years I do a single spray of copper fungicide at pruning time and no other spraying. Your experience may be different and lead to different conclusions.

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