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rett_gw

Organic way to treat black spot????

rett
17 years ago

Is there an "organic" way to fight blackspot? Meaning, is there a way to fight this without chemical spraying? I heard somewhere that a mixture of water and low-fat milk will work? Although I don't know the ratio etc.

If I only had a few roses I wouldn't worry so much about the chemicals, but with as many as I have, I feel like my yard has become a toxic waste dump. :-)

At any rate, any help would be appreciated.

Rett

Comments (150)

  • RosariumRob
    16 years ago
    last modified: 9 years ago

    LOL, these discussions have been going on for years, resurfacing to a higher state of activity now and then. It's nothing new. Only the people progress. It starts when you are new to roses. The roses get BS. You don't want to spray synthetic stuff, because it's scary. So you start an organic routine. It works and you feel superior to all those who spray synthetics. Then the BS hits again. Ouch. So you bring out the big guns and the BS dissappears. Wow. Now you feel superior to all those who tried the organic routine, because spraying synthetics works so much better. Then for some reason you miss a couple of sprays. And the BS comes back with a vengeance and defoliates half your roses. At that moment you realise that spraying is just too much fuss for such lousy plants that roses actually are: plagued by disease and insects, flowers wilt in rain and crisp under heat, the bush form is nothing to write home about, etc. etc. etc. and everytime you think you have everything under control another disaster strikes.

    So you decide to grow dahlias, daylilies, grasses and the occasional bullet proof Kordes rose and become a truly illuminated gardener...

    Discussion closed.

    Rob (hmmm, I can't believe I'm still trying to hybridize roses...)

  • michaelg
    16 years ago
    last modified: 9 years ago

    Several people seem to be miissing the point that there is a reasonably effective organic way to control blackspot in a severe blackspot climate, and I've been doing that for fifteen years. Olga does it, too. You have to be faithful, though.

  • pete41
    16 years ago
    last modified: 9 years ago

    Reasonable is ambiguous.LOL
    I have seen zero blackspot this year even though its all around.Since I am doing nothing wrong by spraying-thats reasonable-
    People who refuse to help control the situation are being unreasonable IMHO.
    About like going to work with a cold.
    Typhoid Annie's and Arnie's.
    Ban them all,better yet mandatory spraying.Spray the roses too while we are at it.Tic[tongue in cheek]Glass in hand-Carlo Rossi -now thats debatable.

  • palisade
    16 years ago
    last modified: 9 years ago

    From Pete"Nope-six months for pointing out dual standards-lo"
    OK, just dont disappear again.
    Michaelg, how do you do it your way?
    Tracy

  • williamcartwright
    16 years ago
    last modified: 9 years ago

    Michael, can you tell us more about how you use sulfur? Sounds interesting.

    Bill

  • michaelg
    16 years ago
    last modified: 9 years ago

    I spray Bonide micronized sulfur (costs $2 a pound), 2 TB /gal with 1 TSP dish soap and sometimes seaweed. I spray the susceptible roses once a week, every week, after watering, usually in the morning. I have to avoid applying anything oily or waxy while sulfur is on the foliage. I have had to discard some roses that were too susceptible for my methods, not many.

    If it got real hot here, which it doesn't, I would skip a spraying. We don't get over 90 very often, but my garden is 5-10 degrees (shade temperature) hotter than the official air temp because it is somewhat enclosed and gets reflection from 140 sq ft of glass. So it is often 90-95 degrees for a while on a summer afternoon. This is around the upper limit for using sulfur.

    I don't have ethical objections to synthetic fungicides, but it is just more pleasant to spray something you know is safe. Also it's pretty easy to grow roses without synthetic insecticides. I've used lots of stuff and still have some around, but I don't need to use it. Well, I used some old Orthene last month on a houseplant fern that was too big (5 x 6) and dense to treat effectively with oil spray-- that's an example of need-to, more or less. But nothing on the roses beyond soap and oil for some years.

    There are some more remarks about sulfur higher in the thread and on the Organic Roses FAQ.

  • williamcartwright
    16 years ago
    last modified: 9 years ago

    Thank you Michael. Most informative!

    Cheers,
    Bill

    P.S. If you have a chance to evaluate any information on "activated compost tea" I'd like to hear your thoughts.

  • bettym_grow
    16 years ago
    last modified: 9 years ago

    Hey Bill, I really do think you are awesome for sticking to your guns. We've had some differences in a previous post but I truly respect you. You know how to handle yourself with style & patience.

    I think all viewpoints should be considered on this forum. It is good to have an open mind & not belittle or degrade people w/ differing viewpoints. If we only had one way of seeing things this would be a terribly boring place to visit.

    Keep being you Bill:)

    Betty

  • buford
    16 years ago
    last modified: 9 years ago

    william, I really don't want to argue with you, but you did attack me upthread for a lighthearted remark I made in another thread. I don't feel I attacked you, but I am miffed at how you choose to present your 'facts' to me. And most of your 'facts' are mere conjecture that even other posters have disputed.

    I did say you were turning people off. You, on the other hand, implied that I did not have a 'modicum of understanding' had a 'radical and dangerous uninformed mind' and that I am 'spouting nonsense' and that I 'have no idea what I am talking about'. A bit 'toxic' if you ask me.

    You said that fungicides damage plants, they do not. I've made it clear to you time and time again on this board that I spray my roses and nothing you will say, no matter what manner you say it, is going to change my mind. So if you don't want to argue, I suggest you simply stop directing any posts to me.

  • kublakan
    16 years ago
    last modified: 9 years ago

    Observation:

    You can tell when we're all dealing with BS when a discussion that has had several incarnations (or is it intypations) garners this much attention and creates such a disturbance in the rose force.

    Thanks to all for your suggestions and for others for the entertaining drama. It kept me from thinking about the battle going on in my yard for a bit.

    Adrian.

  • williamcartwright
    16 years ago
    last modified: 9 years ago

    I'm more than happy to disengage with you. But please read your own posts and re-think whether calling someone an "alarmist" or "psycho" doesn't constitute a personal attack.

    You say: "there no evidence that fungicides damage plants orcause fungi. And promoting that idea on a rose forum is misleading".

    And I patiently try to explain soils that need fungi to be healthy, and point to a horticultural Phd who says:

    "Fungicides kill all the fungi they encounter. While they can be effective against plant disease, they can destroy beneficial fungi and cause serious problems to plant survival."

    You respond that I'm "turning people off" and call me a "virulent anti-sprayer" and say that you want to kill all fungus in your soil, "that's what I want them [fungicides] to do"

    At this point I became less polite in my response to you than I wish I'd been, but I felt provoked and annoyed by your ongoing personal attacks (in this thread and others), and that you patently refuse to accept the fact that beneficial fungus is vital to plant health, ignoring basic soil science, while telling me I'm wrong.

    Since, as you say, nothing I say "is going to change your mind" I will happily no longer waste my time directing posts you. Please feel free to do the same.

    Bill

  • palisade
    16 years ago
    last modified: 9 years ago

    Michaelg, thanks for explaining your way to control blackspot. I dont think sulfur is strong is enough here for me. But there is a limit for me even with using stuff like Banner Maxx. I asked a question about Zephirine Drouhin on the antique rose forum and Olga basically said it will de-foliage. Soil drench is out of the option because of the fish pond. But its hard to find no thorn climber like that.
    Tracy

  • maggie_berry
    16 years ago
    last modified: 9 years ago

    Michael,
    If I have been spraying roses with the ortho products and deer off to the mix,can I switch over to sulfur this year?
    I concerned about the oil on the leaves you mentioned.
    Thank you

  • quitecontrary
    16 years ago
    last modified: 9 years ago

    I'm with rosariumrob! Yes, we have been discussing this topic for years. I did go through gardening "developmental stages" with respect to pesticides. In the beginning, I would panic if I saw any pest damage and run to the store to buy some bottled remedy. I did notice that I was killing more plants of all kinds with pesticides than I was losing to the pests themselves. I then went the organic route. If I wanted to spray something organic on roses, I would probably go back to micronized sulfur. I have always wondered whether it might to useful to mix the sulfur with wilt-pruf. However, that is too much trouble for me now. My disease control program is the shovel. I believe in growing things that are well adapted in my yard. This includes roses. I have grown roses in the northeast and in Florida. Yes, it is harder in Florida. Most roses are not well adapted to Florida. However, the subtropical environment of Florida offers other delightful gardening opportunities. There are even a few roses that are easy to grow on their own roots in central Florida. Cramoisi superieur is one example.

    I don't think we need to indulge in personal attacks on Garden Web. In fact, they only distract us from the serious topic at hand. There are many unknowns about the effects of garden chemicals. Many consider fungicides to be safer than insecticides. This may not be the case. Much current research investigates chemicals, including fungicides, that may be endocrine disruptors. Those who are interested can google that. I have linked to a summary that may be a useful starting point.

  • brandyray
    16 years ago
    last modified: 9 years ago

    Sandy808- we should all heed your message to lighten up a bit! Roses are for enjoying and if it becomes a big struggle, it's time to switch roses, move, or start w/ a new plant or hobby. Personally, I find looking at the herbs in my garden relaxing and watching the bird feeder- no BS there or mildew either. Lots of fungus here, big patches on top of some of my mulch. My roses are healthy, so far... If I they got sick, I would use organic methods and if that didn't work, I guess I'd experience the sorrows and joys of shovel pruning for the first time. I don't consider this to be a very good climate or soil for roses, so I am limiting them. Trying to get resistant ones- still looking for a really good list for zone 8a.
    I hope we can all disagree w/ respect and love. There is too little serenity in the world and flowers ought to increase the serenity, not decrease it. Brandy

  • bettym_grow
    16 years ago
    last modified: 9 years ago

    Kublakan,

    Another observation:

    I've gained 2 pounds from sitting here in front of this computer instead of being out in my garden weeding, pruning,etc...

    Betty

  • sandy808
    16 years ago
    last modified: 9 years ago

    Yeah Brandy! It's trial and error with finding the right roses. I still think it is far easier growing them in the south than in Upstate NY where I moved from. The winters are hard to deal with up there. Eventually, if you work on it, you can have some pretty decent soil. Use organics and lots of compost, and leave enough room between bushes for good air circulation. At one time everything was planted too close together beacause I wanted to squeeze as many roses in as I could. I've since re-spaced my roses farther apart and have very little disease issues now.

    I use integrated pest management with the roses that need that and it seems to work well. It's not totally organic, but at least it's minimal chemical use. Most of my roses don't need to be sprayed at all, but I do have about a dozen hybrid teas. I kept only the disease resistant ones, and so far they are beautiful with a minimal spray program. I took the Antique Rose Emporiums' advice and spray only on an "as needed" basis. Some years we are very rainy and humid, which results in lots of blackspot. I find those times make it necessary to be more consistant in the use of fungicides until the weather pattern becomes nicer, at which time I can back off on them.

    This works for me. It may not work for someone else, and I would be the last person to tell someone else what they should do - other than cover yourself up and don't breathe it in. (And don't get overspray on your birdbaths, fountains, and bird feeders. Cover those up too). When it comes down to it, we all have "custom" gardens. No two are alike, and we have to customize the care they receive.

    Sandy

  • dublinbay z6 (KS)
    16 years ago
    last modified: 9 years ago

    Sandy, I would be interested in knowing which HTs are disease-resistant for you.

    Thanks,
    Kate

  • michaelg
    16 years ago
    last modified: 9 years ago

    maggie berry-- Deer Off contains whole rotten eggs; the oil in the eggs might or might not be a problem. You would need to do a test spray on a limited area of a few different roses before spraying the whole garden. Wait 10 days for evidence of burn damage. I think there are other products that only use egg whites which might be more compatible with sulfur. Residues of Ortho fungicide and insecticide should not be a problem.

    palisade--
    Did Olga say Zepherine defoliated despite sulfur spray or as a no-spray rose? Olga has some of each category. I grew ZD for several years with sulfur, and she had some blackspot but never approached defoliation, didn't look bad. She would certainly defoliate here without spray.

  • palisade
    16 years ago
    last modified: 9 years ago

    Michael, I went back to re-read the thread. Olga didnt say what she spray with because I asked if I could grow it no spray so I think she meant de-foliage if no spray. Olga are you around ? Even where Florence is, hers grow so big and I dont want to be on a ladder to spray it. If I can somehow grow it as a 6 ft tall shrub wider is ok I can follow her experience on how to keep it looking full.
    Tracy

  • collinw
    16 years ago
    last modified: 9 years ago

    I live in Alabama, just south of Birmingham, where the growing season is very long and the Black Spot pressure is severe. Similiar to Bill, I have observed many local rose growers that spray fungicides plagued by one problem after another. While my garden stays on an even cycle.

    I am not saying that I do not get blackspot, but that through careful selection of roses and careful maintenance of the soil, I rarely have a rose that is completely defoliated. Usually that is a rose that I get rid of. But I have seen roses improve their immunity with age. But at any given time there are some roses with minimal BS in my garden, especially after the 1st spring flush. Personally, I can live with a few chewed leaves and some black spot.

    Fungicides kill the benificial soil fungus as well as the 'bad guys'.

    You guys might be interested in the following blurb on beneficial soil fungus.

    What are mycorrhizae?

    More than 90 percent of plant species form a symbiotic arrangement with beneficial soil fungi called mycorrhizal fungi. The roots are colonized by the soil fungus, which attaches to the roots and extends far into the surrounding soil environment (figure 1). The colonized root is called a mycorrhiza. Mycorrhizal fungi are the dominant microbes in undisturbed soils accounting for 60 percent to 80 percent of the microbial biomass. Mycorrhizae are fundamental to plant establishment, supplying the water and nutrients needed for survival and, in exchange, receiving essential sugars and other compounds supplied by the plant. There are basically two broad groups: those forming ectomycorrhizae, so termed because of the external modificationto the root, and those termed arbuscular mycorrhizae (also termed endomycorrhizae), the name coming from the structure formed within the root cells. Unlike the ectomycorrhizae, no external modification of the root accompanies arbuscular mycorrhizae.

  • michaelg
    16 years ago
    last modified: 9 years ago

    Tracy, Olga sprays with sulfur, but she tries some roses out as no-spray candidates and she has many no-spray roses, mostly gallicas, albas, etc, I believe. I think your interpretation is probably correct, defoliation without spray.

    As you say, it is a nuisance spraying any really large plant. My ZD grew to 10 x 10' with dozens of basal canes, and I got tired of spraying her, since a pretty thorough job was needed to keep her looking good. Renee is a thornless climber that is no-spray in some gardens. Heritage, a large nearly thornless shrub, needs much less spraying than ZD.

  • palisade
    16 years ago
    last modified: 9 years ago

    Michael, thanks a lot. I will look up Renee and Heritage.
    Tracy

  • pete41
    16 years ago
    last modified: 9 years ago

    Some let the problem control them by limiting their choices and accepting unsightly plants.Rationalizing
    Others prefer to control the problem and enjoy beautiful bushes of their choosing.Rationalizing
    However I sincerely doubt that all the home rose growers put together are threatening the fungi of the world.lol

  • banders
    16 years ago
    last modified: 9 years ago

    Renee needs no spraying in my garden, but she's far from thornless. FEW thorns, and they're not HUGE, but they will let you know they're there if you get too close. Same for Climbing Pinkie, which I've also seen described here as thornless. Nevertheless, I LOVE both of them.

    Barbara

  • anitra
    16 years ago
    last modified: 9 years ago

    I haven't raised roses. I did have black spot on my green peppers this year. What worked most effectively for me was making a paste from fresh worm castings and dechlorinated water, and applying it directly to the affected areas of the plant. I re-applied it every other day for a week, and all black spots faded and didn't come back.

    I don't know whether this would have worked as well with commercial, packaged wormcastings; I used mine straight out of the bin.

  • cindyabs
    16 years ago
    last modified: 9 years ago

    So my question is what can I use to spray that will not harm my dog or cats as they wander through my rose beds?

  • buford
    16 years ago
    last modified: 9 years ago

    Cindy, I have cats that go in my flower beds. I use the Bayer spray. I simply don't have them outside when I spray, and once it's dry, it can't transfer to them.

    Also, did you know that Immidicloripid (insecticide) is the active ingredient in flea treatment? And that Sevin can also be used directly on cats and dogs to kill fleas (in the right concentration of course).

  • anne_horton
    15 years ago
    last modified: 9 years ago

    Michael -
    Could you please post the exact recipe you use for your spray- i.e. what kind of seaweed (liquid???) do you use?

  • dez818
    15 years ago
    last modified: 9 years ago

    Well, I love my roses-all 150 of them, but in the heat of the spring/summer-the mosquitoes get outrageous in my area so they really have to fend for themselves when it gets warmer. The most I've ever sprayed is the cornell formula, and even then, not regularly. Most of my Austin roses do pretty well as do my OGRs, teas and KOs, but BS is a fact of life here in the south. Living in GA and trying to grow hybrid teas would be a never ending nightmare. None of my roses have been completely defoliated from my benign neglect, but I also like a cottage garden style, so there other lovely plants to cover up unsightly knees. In my yard, only the strong survive LOL

  • roseman
    15 years ago
    last modified: 9 years ago

    All I can say to you is: "Lots of luck!" This is one problem that cannot be handled organically. The chemical way IS the ONLY way. But believe what you choose. Believe me, if organics worked on BS, we would all be using it. We aren't, and you will not be successful with it either.

  • henry_kuska
    15 years ago
    last modified: 9 years ago

    Regarding statements of the type: "This is one problem that cannot be handled organically. The chemical way IS the ONLY way."

    The original question was from someone in zone 6. Yet, people in much warmer zones apparently feel that only their experience is applicable. I do not follow this logic.

    ------------------------------
    I am in zone 5, I have about 1000 roses. I do not spray so I cannot comment on any organic solutions. Has anyone in zone 6 tried the method studied in the following report:

    http://www.ecostudies.org/FTGG/FTGG-12-13-04.html

  • henry_kuska
    15 years ago
    last modified: 9 years ago

    The link below gives the abstract of a recent biocontrol research paper:

    http://www.informaworld.com/smpp/content~content=a783868824~db=all~order=page

    Unfortunately in the abstract they did not give numbers. In the full paper they summarise in their Figure 9 their results 75 days after spraying the rose "Edward". The no spray control had a "percent disease index of about 65, the chemical spray control (using Tridemorph) had an index of about 35, Pseudomonas fluoresens treatment had an index of about 45 and Trichoderma viride treatment had an index of about 40.

  • sandy808
    15 years ago
    last modified: 9 years ago

    I grow blackspot resistant roses, and let it go at that. I gave up any desire to spray a long time ago. Our summers are too darn hot to deal with it, and I also want to minimize my chemical exposure. There are many teas and chinas that I grow no-spray that keep beautiful foliage, bloom exceptionally well, and thrive. They are beautiful garden plants.

    Most hybrid teas, however, would be a disaster here without being sprayed. They are beautiful, but I can't deal with the heavy care routine that is involved with them, in Florida. In other areas of the country, hybrid teas stay very healthy on their own.

    The best way to deal with blackspot is to grow blackspot resistant roses for your own particular area, if you want to grow roses organically. Otherwise, you will need to have at least a minimal spray routine to keep them looking decent.

    Only you can decide.

    Sandy

  • User
    15 years ago
    last modified: 9 years ago

    1) Select varieties that are noted for their health in your specific region. Recommendations from local societies and independent growers will be useful in making your selections. If you insist on selecting from the modern Hybrid Tea and Floribunda classes, you can be fairly certain that disease issues will continue to plague you in a fungicide free garden. Sad but true.

    2) Many cultivars will gradually build up resistance to disease as they mature. I have found that numerous cultivars in my garden which had to be sprayed in their first three years in the garden have "acquired" resistance to fungal diseases now that they are 7 to 10 years old.

  • len511
    15 years ago
    last modified: 9 years ago

    I suppose I feel fortunate not to have that big of a bs problem despite what I hear from those around me. I also have high humidity, etc. I have roses in every class and have never chose or disregarded a rose because of bs or mildew. I don't spray. I only had 1 rose defoliate late last summer, but it grew a new full set of leaves by early fall and never got any more bs, despite others getting a small dose, it was baron girod (sp.). Mine are mainly grown in the lawn or pasture with grass. I had 2 r. Wichuranas, one I had to search for in the tall grass that was totally bs free, while the one with more exposure had a little bs. I quit mulching also as most just blew away. The ht's I planted didn't fare any worse than any of the others. The ht's are mainly the older ones, no moderns. We'll see next year, as I planted more ht's and floribundas, many pernetian style,this fall. I noticed many of these had comments that they do better in a hot,dry climate, LOL!

  • brhgm
    15 years ago
    last modified: 9 years ago

    None of the organic blackspot remedies seem to work here in Louisiana. I try to plant blackspot resistant roses and antiques that bounce back from leaf loss. Mildew is only a problem on cold dry nights and in Louisiana it usually rains a lot in the winter and spring. I agree that knockouts and their rivals and antiques appropriate for my climate are the way to go for me.

  • hoovb zone 9 sunset 23
    15 years ago
    last modified: 9 years ago

    Actually the best way to deal with blackspot may be growing your roses in inland Southern California. No blackspot there. Other growing challenges, yes indeed, but blackspot isn't one of them.

  • sandy808
    15 years ago
    last modified: 9 years ago

    Every region has roses that do very, very well, and with only minimal disease issues, if any at all. I truly believe, based on my own personal experience, that there are lots of beautiful roses that can be grown no spray.

    However, that doesn't mean that you can grow EVERY rose your heart may desire, in a no spray or blackspot free way. When any of us wants to grow a particular class of roses that have never been able to adapt to our individual unique climate, then disease happens. What does great for me won't necessarily do well for someone in N.Y. What stays healthy in California may or may not stay healthy in Florida. I quit fighting nature and just roll with what does well without a fight here, and enjoy looking at and hearing about other types of roses when I travel. That's me. Other people enjoy more of a challange in their gardening.

    I have grown a few hybrid teas no spray. They do get some blackspot and defoliate to some degree, but as long as the majority of the time they do well, they are welcome in my garden. So far Tiffany and Queen Elizabeth are still welcome. I pick off their cruddy leaves. As a whole though, hybrid teas need some spraying in Florida. None of the chinas do, or most of the old teas.

    Sandy

  • the_gurgler
    15 years ago
    last modified: 9 years ago

    I am also working on some black spot troubles with my roses. Has anyone tried Neem based sprays? It does have anti-fungal properties as I have used it to get rid of ring worm in the past.

    Perhaps I shall run my own experiment with a Neem spray. My only reluctance would be that Neem will harm your beneficial insects, but timing might help with that.

  • henry_kuska
    15 years ago
    last modified: 9 years ago

    I tried mixing Neem with Wilt-Pruf. In limited testing, I thought it actually stopped existing blackspot.

  • User
    15 years ago
    last modified: 9 years ago

    Perhaps fungicides kill the commencial fungus which lives on the roots of some plants and trees. Various plants and trees are utterly reliant on this fungus to obtain nutrients from the soil. If the fungus dies, so does the plant. I don't know if roses have beneficial root fungus, but if they do, fungicide application would cause gradual decline and death.
    I don't spray. I select disease-resistant plants and try to keep them watered, mulched and fed so that they can fight off the fungus naturally. I make sure that they get enough sun so that the UV will kill the fungus on the leaves.
    I have also read that watering roses in the evening and splashing water on the leaves can encourage black spot, especially water that has splashed up from the ground onto the plant.
    Has anyone had success with baking soda and water spray for BS? The effects of this spray on the surrounding soil could be easily counteracted by any acidic fertilizer or organic soil amendment.
    good luck and please keep the forum cordial. thanks,
    Avalon

  • User
    15 years ago
    last modified: 9 years ago

    "I don't know if roses have beneficial root fungus, but if they do, fungicide application would cause gradual decline and death."

    If this were true, thousands of Rose growers who spray consistently, every year, would be struggling to keep up with replacing an every growing list of dying specimens. We know this not to be the case.

  • User
    15 years ago
    last modified: 9 years ago

    Please allow me to amend my previous statement: "I don't know if roses have beneficial root fungus, but if they do, fungicide application would cause gradual decline and death" to "...MIGHT cause gradual decline and death, and would certainly negatively affect the health of the plant." The fungicide would be unlikely to irradicate all of the beneficial fungus population, just reduce it. I'm sure that rose growers who spray are not replacing their roses all the time, but I do get the impression that many people are giving up on certain varieties because they are so susceptible to BS. I don't think that the possibility of fungicide interfering with the over-all health of the plant can be ruled out until it has been conclusively proven by reproducible research on rose mycorrhizal fungi that roses don't have comensal fungus.

    Ignorant newbie question: Can bs actually kill a rose? I don't have much experience with alot of blackspot on otherwise healthy roses. The roses in my area should be grafted on Fortuniana. In the past, I have had roses on Dr. Huey that succumbed to blackspot so badly that I didn't know if it was the rootstock failure or the BS or the combination of the two that killed the plant. I have some of the same varieties now on Fortuniana and they don't have nearly the amount of blackspot that the Dr. Huey's had.

    My point is that if the roots are healthy, the plant will be able to fend off disease more easily. IF
    (BIG "IF") the roots have comensal fungus, then applications of fungicide could actually contribute to a viscious cycle of "spray... BS better... roots worse... BS worse... spray..." -I'm sure you get my point. Again, this assumes that roses have beneficial fungus on their roots. Does anyone out there have an answer on this one? I guess
    I could always search the net....!

  • henry_kuska
    15 years ago
    last modified: 9 years ago

    If you do not have the natural mycorrhizal fungi in the soil, it appears that high phosphorus can substitute, see:

    http://www3.interscience.wiley.com/journal/119491079/abstract?

  • buford
    15 years ago
    last modified: 9 years ago

    avalon, your post doesn't make sense. People are giving up on BS prone roses because they get BS and don't want to spray, not be cause the roses are dying because people are spraying fungicides.

    I spray my roses regularly and they are thriving. No problems with roots or any growth. In fact, they do better when sprayed because they don't lose leaves. If I spray the leaves, that isn't going to have a big effect on the fungus in the soil.

    I've had blackspot on all my roses, every kind. I've even seen black spot on neighbors knock out roses. IMO/E it has less to do with the health and type of rose than the climate conditions of where the roses are being grown. I've had years where I have had little to no black spot and years where no matter what I do every rose has black spot. Same roses, same yard, different weather conditions.

    I don't think black spot alone will kill a rose, but it will weaken it so that it will not thrive or bloom and then can be subject to other damage.

  • User
    15 years ago
    last modified: 9 years ago

    Questions for Buford: How old is your oldest rose plant?
    Would you say that your rose plants have had their lives extended by spraying? Have any of your roses ever died from an unexplained cause? Have you ever given up on a particular rose because of BS even though you spray? Also, what kind of spray do you use? (Perhaps you mentioned this in a previous post that I haven't read yet, so please don't be annoyed if I'm asking you to repeat yourself. Also, please don't be offended by the series of questions - I'm not trying to be obnoxious, I'm actually trying to learn.)
    It is possible that the people who are spraying all the time are simply keeping the roses that can withstand the climate, soil and the constant spraying. It may also be possible that the difference between one fungicide and another may be enough to provide one person with evidence that spraying works, while someone else with a different climate and soil type may find that particular fungicide to be ineffective or even harmful. I know for a fact that some fungicides can damage plants, even when applied as directed. I just don't know much about fungicides on roses.
    avalon

  • henry_kuska
    15 years ago
    last modified: 9 years ago

    See:

    http://www.ncbi.nlm.nih.gov/pubmed/17033931

    and

    http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WDM-4T9JWDV-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=89e05e399a266e230d935bb7d580aec0

    and

    http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=6610374&q=allintitle%3A+roses&uid=789871398&setcookie=yes

    The following is part of the abstract:

    "Although symptoms of black spot on roses in the Bayer All-in-One treatment was significantly less than those in the controls, the plants were stunted and had significantly smaller flowers than roses within other treatments."

  • buford
    15 years ago
    last modified: 9 years ago

    Currently I use Bayer Advanced disease control. Prior to that I used Daconil. With Daconil, I had to spray every one or two weeks. With the Bayer, I can spray every 3-4 weeks. I haven't noticed any damage to the plants, but I use the proper concentration and spray early in the AM and make sure the roses are hydrated before spraying. Any chemical can be damaging if not used properly.

    I haven't noticed any play suffering because of spray, quite the opposite. I have a couple of roses that did not do well until I started spraying regularly. Peace and Double Delight are two examples. On Peace, I did not get more than a handful of blooms on it until I sprayed regularly.

    Most of my roses are 7 years old and under, since that's when I first started growing them. I've lost a few to drought conditions (mostly newly planted roses that didn't make it). I believe I had a few that had RRD and I did take them out and dispose of them. It's possible at some point I would replace some roses that are susceptible to BS, but frankly I don't ever envision me having a no spray garden here, so since I spray, I can grow even BS prone roses (such as Peace).

    Again, the spray goes on the leaves and maybe the top layer of mulch, so I don't think it would penetrate the soil in any concentration to eliminate all the good fungus down there. I use mostly organic fertilizers and believe I have fairly healthy soil.

  • User
    15 years ago
    last modified: 9 years ago

    Hi Buford,
    Thank you for taking the time to answer all of my questions. I'm going to try to avoid commercial fungicides for now, partially because the previous owners of our property already poisoned the soil with Round -up. They really used way too much of it. Some of our fruit trees are actually deformed because of over-application, and we had no earthworms. I had to re-introduce them in the yard. In the future, if I do use fungicide, I will try a very light application of Bayer.

    Thanks again,

    Avalon