A relatively recent (2007) controled reviewed scientific research paper covering 2 years of actual field trials is at the link below.
-----------------------------------
A 2001 article gives a historical review (with references):

http://www.national-toxic-encephalopathy-foundation.org/fungicide.pdf

Here is a link that might be useful: relatively recent controled scientific research paper

A 2012 reviewed scientific research paper concerning the control of blackspot by natural products.

Here is a link that might be useful: link for above

Reg is a good poster, but his post above has some errors. He says all sulfur sprays are toxic to bees. As the link below (from Cornell ag) says, "Sulfur is considered non-toxic to bees."

Do not confuse elemental or plain sulfur (which I recommend above and which is very safe) with lime sulfur, a toxic compound.

Also, while whole neem oil (such as Triact) could be toxic to bees, the commonly available neem oils ("water extract of neem" such as Rose Defense) have had the insecticidal fraction (azadiractin) removed, and these are probably no more toxic than canola oil.

Here is a link that might be useful: (Non-) hazards of elemental sulfur

If there was any organic fungicides that worked, don't you think everyone would be using it? The fact that no one can give you an answer should indicate there is no such organic fungicide

Rats. There go my get-rich-quick schemes for my retirement fund that were based on milk, baking soda, Tide, and magic beans.

Hehehe....yes--they do, as you can tell, as I am FULL of it.

Henry, Chalker-Scott cites her references on "The Garden Professor's website on Washington State University's Extension site, and in her books, The Informed Gardener and The Informed Gardener Blooms Again. The publication I cited in the previous post is a "lay" publication meant for the general public, not for you and I to assess her expertise on.

Competing references are important for scientists to debate, but this is not the forum for dueling references...and it's not my field of expertise so I tend to follow Chalker-Scott.

A forum is a place to try to determine if points presented are accurate.

"Many woody plants are directly connected to neighboring plants of the same species and any herbicide treatment applied to them can be translocated to other individuals sharing that common root system. Suckers produced by roots of an adjacent tree are an example of a shared root system. Cutting and treating these sprouts with an herbicide can result in translocation of the active ingredient to the common root system and may ultimately kill non-target trees. In some cases, trees of the same species growing in a given area may have a common root system as a result of root grafting. Never use herbicides to treat sprouts coming off a root system of a tree that you want to keep or on plants that may be sharing a common root system. Sucker producing tree species include: tree of heaven, honey locust, black locust, hackberry, western soapberry, cottonwood, aspen, poplar, willow, box elder, and others."

Please note: "This information has been reviewed by university faculty."

This article was produced in 2006.

http://arizona.openrepository.com/arizona/bitstream/10150/144792/1/az1401-2006.pdf

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Another recent (2008) reference:

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74142.html

"Regrowth from cut stumps can be sprayed when leaves fully expand. Cut stump application of glyphosate can sometimes injure nontargeted plants of the same species in close proximity to the treated plant. This occurs via herbicide translocation through root grafts. This type of root grafting damage depends on the species. Rarely, if ever, does root grafting occur between plants of different species."

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74142.html

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Announcement of new carbonate formulation.

Here is a link that might be useful: Announcement of new carbonate formulation.

Serenade works very well for me.

Bayer Natria is apparently similar to Serenade.

Kaligreen and Remedy are two brands of potassium bicarbonate, similar to Armicarb in Henry's link. Potassium bicarbonate is very effective against powdery mildew.

In my experience, Serenade or carbonates work for powdery mildew as does milk. But none of these are effective against blackspot.

Actinovate *seems* to work on blackspot. It is rather expensive and inconvenient, but worth it for me so far.

Yes both Bayer and Serenade use the same QST 713 strain of subtilis, hmmm.

Any way I use it for black spot first and any other second and it works extremely well for me, although I soak, using a five gallon pail, the area around the rose(I do not use five gallons per rose). I do not just spray the rose.
It also stopped the leaf-spot in my strawberries dead in its tracks.

Keep in mind the original post was from zone 10 in Florida where blackspot pressure is greatest. Organic fungicides or even regular fungicides that work in colder zones probably won't be effective in Hot Humid and wet Florida.

Concerning the statement: "Organic fungicides or even regular fungicides that work in colder zones probably won't be effective in Hot Humid and wet Florida."

H.Kuska comment: I cited 2 research papers in this thread one studied roses in Mississippi and the other studied roses in Tennessee.

Also please remember heat turns "off" blackspot. "A temperature of 64�F is optimal for black spot development, but conidia germination still occurs from 59 to 81�F"

The above quote is from following Florida link.

Please note that they apparently feel that some of the organic type treatments are worth recommending to Floridians.

Here is a link that might be useful: University of Florida blackspot information

I have experience growing roses in Florida and here in Southern Appalachia. My impression is that blackspot is slightly worse here. (Not to belittle the problem in Florida, where it is certainly very bad.) In turn, the BS problem is worse in Florida than inland Texas or the Deep South because summer nights in Florida are not extremely hot. To get BS germination in summer, you need an evening shower and overnight temperatures in the 60s or 70s for a long period. The worst BS conditions involve frequent light rain and moderate temperatures, with high humidity to retard drying of the foliage. BS tolerates heat better than the other major diseases, but it does not prefer heat.

I'm a bit confused by this temperature thing. Summer in Florida is hot 24 hours a day. If it dips to the 80's it is a lot. We haven't seen 60's or 70's any time of the day for a while. BS is much worse in the summer than the cooler months. Of course our summer rains have started and it rains at about 4PM daily, so it does sit on the leaves all night.

Another question is will blackspot germinate in the dark in the summer (when the temperature is more conductive to germination). At first I found some indirect references that suggested that germination would be inhibited in the dark, but then I found the link below which did the actual experiment and concluded that light is not a significant factor.

Here is a link that might be useful: link for light research

Its funny I would read this thread. I started using copper sulfate in March Due to some water damage in my bathroom and garage, I haven't been able to anything in my garden since the beginning of April, except to water and cut off spent blooms. I'm almost done with repairs and I noticed yesterday that were no thrip on my roses. I thought it was because I was trying to improve the condition of the soil. I started using cotton burr compost for winterization in the fall. In January, I applied manure to all my plant because I never seem to get out there in time to apply fertilizer in the spring.
I live in humid Kansas so no matter how blackspot resistance a plant its going to get blackspot. Since I haven't done anything since the beginning of April, the blackspot has gotten really bad. I can't use the copper now because its too hot. However, I think I will use the wiltpruf (which I started using last year) and this stuff I got from Garden alive that contains sulfur but also contains pyrethrin. I have a chemical fungicide that I will stop using on the roses. If the thrip come back then I have to experiment with something else.

Most molds/fungi do not require light to grow. They require food, moisture and just the right of warmth/heat temperature to grow.

mori1, I was quite shocked by the thrips help too. I had tried everything, including the $100 insecticide. For 11 months of the year the thrips damage was awful, during the hottest months the blooms were brown mush. An organic rose nursery owner said that if I stop all chemicals the beneficial insects will take care of the thrips. I had already given up on insecticides a while ago and used only organic fertilizer. So I stopped the chemical fungicide and the blooms are now gorgeous. Unfortunately the plants look bad due to the bs.

teka2, yesterday's low for Miami was 74 and lows of 75-76 are predicted for the rest of the week. IIRC, these are typical overnight temperatures for Florida in summer. In Texas, overnight lows above 80 are very common (but not happening this week).

OK, maybe it does get that low in the middle of the night. I guess I sleep through it. I truly appreciate the knowledge of the posters and I sincerly mean that. Otherwise I wouldn't post questions. My point was what do I do about the black spot now? It's nice to know it's cause, but I have no control over the afternoon rain or the temperature. I know not to water late or use the overhead sprinklers. Thanks for all of your help.

Well I never did use much in the way of fungicides in this garden. It is 4 years old now. A year ago I used a little sulfur on my roses. Since then I have used NOTHING. Let me tell you folks this year my roses look great and next to nothing in the way of BS. A little for sure..but not much.

I know that here in N Georgia, during late July and August, I can spread out my spraying to 3-4 weeks. It is so hot, even at night, that the BS doesn't grow as much. Of course the past few years, it's also been very dry during that time. Which was good for the BS, but not good for having to water everything in the heat.

I doubt that fungicides have any effect on thrips or thrip predators. When I stopped using the systematic insecticide (the Bayer drench) I started having thrip problems.

I actually never tried chemically to get rid of the thrip. I have a bioinsecticide but I bought a few years ago for the horrible bagworm problem I had. Since the bagworms are no longer a problem, I haven't had to use it. If it worked on cucumber beetles then I would continue to use it but its only for severe problems as it can kill bees. Supposedly, pyrethrin might help in this regard, so we will see. I had lacewings and praying mantis in my garden for several years(but not last year or this year either) which helped with the aphids but did nothing for the thrips or cucumber beetles. Aphids were bad but like I said just didn't have time to deal with it. So on my future list is lacewings and a bat house.

I am with Karl. Nothing really works for black spot that may be considered "organic". (I don't consider copper sulphate organic). Since all the usual synthetic fungicides have been banned for residential use, and I m not prepared to spray anymore, I have learnt to live with it. I only grow relatively resistant roses and keep them healthy. Keeping up a running battle with black spot is too much stress and spoils the enjoyment of gardening - so I just accept it as the wills of nature.

For those of you who let nature take it's course, do you keep the black spotted leaves cleaned up on the ground around the bushes? If not are there problems?

I am going to withdraw my suggestion of sulfur, at least during the rainy season, because it would be so hard to keep the material on the foliage. October through April, sulfur might be helpful. You might try Wilt Pruf or
Cloud Cover--see my post above. This might help significantly on the roses that are somewhat resistant, such as the old teas.

I spray less often in the heat of summer. I am thinking about trying a weaker concentration of chemical to see how that compares.

There is a thrip remedy that doesn't involve spraying: buy blue plastic drinking cups, paint the insides with STP oil treatment and put those upside down on stakes in your garden. I bought the stuff but didn't try it. Some people say it works.

Regarding nature taking its own course--

I clean up the deadheaded material, but I am remiss regarding infected leaves that have fallen. There are a few things that I just won't do, and this is one of them. I'd have to quit my day job to pick up all the leaves. Between the limbs blowing out of the 15 trees around us, the dog digging holes, and incessant watering, I'm outside all day anyway on days off. The leaf-gathering chore is one that I pass on.

Yes, it probably would help to clean up the ground around the roses, but they are planted fairly close together and the grafts are mostly below ground. There just isn't much space under each rose for maneuvering, and the biggest, gnarliest thorns are on the basal canes. I've already been stabbed enough this year when applying fertilizer. (It's supposed to be blood meal, not actual BLOOD.)

Untreated, the roses can look pretty shabby. With a light spraying schedule and a devil-may-care attitude on leaf drop, they're about 80% clean. Some things you just can't prevent. I know we're supposed to NOT typically water from overhead, but water does fall from the sky here periodically. Less this year than normal, but it happens.

Picking up all the fallen diseased leaves doesn't stop blackspot because there are infections in the green bark (showing as red spots) that release spores. This is the main way that BS carries over winter in areas that have winter.

Also the leaves will have released lots of spores before they dropped. Picking off the green leaves with spots could help slow the spread somewhat. This is easier than picking up fallen leaves anyway. I don't pick up fallen leaves.

Thanks guys, I guess I won't kill myself trying to get all of the fallen leaves.
Flaurabunda, I hear you. I am one scar after another. Some days I looks like I've been a knife fight.

When leaves fall on the ground I rake them into ground to recycle them and use them for mulch. I've not found any problems with this.

I do not let Nature take her own course completely. I like to think of it as Nature and I are working cooperatively. As I've mentioned here before, I spray with the Bayer fungicide 2-3 times in the spring and a couple times in the fall. Those are the heaviest BS seasons. It gets so hot here in mid- to late-summer that I rarely need to spray at all--so I don't.

However, the biggest contribution I make to all of this is that I plant only disease-resistant roses, and in fact, prefer the highly disease-resistant ones. I do have a few left over from the good ol' days when no one worried about spraying for BS (couple Double Delights, for instance, and Mrs. John Laing turned out to be a bit more receptive to BS than I anticipated) and I've loved them for years now, so I won't spade them. However, my favorite rose of all time is Peace and I refuse to grow it--it is a disease-magnet and I just won't put up with it as a result, no matter how beautiful it is. While there is only one Peace rose out there, there are many other beautiful roses out there that are also very disease-resistant--that's my kind of rose--the ones I never (or very rarely at most) have to spray for BS.

Here's one that has never exhibited even one blackspot and therefore has never been sprayed--Lady of Shalott. I think this highly disease-resistant Austin is gorgeous, don't you?
{{gwi:215629}}

Works for me in Kansas Zone 6. Can't say about other areas, but I'd think these practices would work, or at least help, in a lot of areas.

In other words, quit looking for the magic (organic) cure. There is none--except for some good judgment and careful choices.

Kate

The following statement was made: "In other words, quit looking for the magic (organic) cure. There is none--except for some good judgment and careful choices."

Even with the "except" I feel that it is too broad of a statement. Please see the link below for a more optimistic statement.

"4.As diseases and severity vary with location, you will have to experiment to find the most effective combination. With all these options, there is no longer any need to use toxic sprays, especially when resistant species and good cultural practices can help prevent the problem in the first place."

Here is a link that might be useful: Least-Toxic Controls of Plant Diseases

Krista thanks for that thought. I have always separated the rose foliage discards from other leaves because of the disease issues. As Michael pointed out and I didn't know, the disease is already on the plant and not just the fallen leaves. Henry and Kate, you are so right. This is my first year without spraying fungicide. It really is the only thing that stopped the thrips. But I am discovering that some of my favs. are not at all disease resistant. I am taking an inventory about who is and who isn't. The Lady is lovely Kate. I have found that some of my most disease resistant varieties are Austins.

Henry, are you deliberately mis-reading what I said? My statements agree almost completely with yours -- with the exception that I spray a couple times during the heaviest BS seasons (spring and fall). Everything else I said agrees with your statements, but you act as though you are disagreeing with my statements.

Or did you not bother to read past my first paragraph? Oh, I guess that was why you didn't notice my comments about planting disease-resistant roses -- the good judgment thing--or didn't you realize that is what I was talking about?

My goal is to MINIMIZE the use of fungicides--to use as little as possible to handle BS. Your goal is to completely ELIMINATE the use of fungicides and let BS take over. Since I have eliminated the use of fungicides on over half the roses in my garden, and only spray the others a couple times in the Spring and Fall, I fail to see why you think I need to be scolded by you. The good judgment I was referring to is pretty much the same good judgment you were referring to.

Yes, I'm ticked off.

Kate

Not all of the chemical fungicides have been banned. There are many still in use and they work quite well.

Kate, I now have at least 10 roses that I don't spray. They never show any sign of BS so I don't bother. But most of mine are lost causes.

Kate, I put your statement in quotes (including your "except").

I am adressing: "are there organic methods that work?" Please note that the title of this thread is: "Organic fungicide that works". I presented links to 2 different reviewed published scientific papers on the subject. I personally conclude from reading them that there are organic methods that work under the conditions that the experiments were carried out under to my satisfaction (of course a rose shower who demands perfection may come to a different conclusion). I then presented a Florida University link with their view on the subject.

-------------------------
Your statement: "Your goal is to completely ELIMINATE the use of fungicides and let BS take over."

H. Kuska comment: I cannot understand how you drew that conclusion ("let BS take over") from either the Brooklyn Botanical Gardens article quote that I cited nor from their full article that I linked to (nor from my earlier posts in this thread).

I drew that conclusion, Henry, because you fail to note two things in the real world.

#1: many rose growers have serious BS problems in their gardens, despite their good garden/rose-growing practices. If they go fungicide-free, there is only one possible outcome: roses devastated by BS. Your advice to them is a guarantee that their roses will suffer serious harm from BS.

#2: My post (which you failed to note) was NOT about those articles. It was about the new group of posters every year who come to this forum asking about the baking soda cure or proclaiming its virtues and wondering why those of us who have been growing roses for years are so ignorant that we don't realize we could go 100% organic and just sprinkle a bit of baking soda around--and all BS problems would disappear. Variation on this was the new poster who put manure around her roses and proclaimed the manure kept her roses free of BS and us ignorant ones ought to go organic and just spread around the manure instead. The same questions/assertions get made every year by some newcomers who visited an organic forum and think banana peels or coffee grounds or some such quick fix that is organic in nature is the obvious answer to any rose-growing problems. Strange how we do not hear from them in subsequent years about the tried and true organic methods of curing BS--or if we do, they confess that none of those methods worked after all. It was those kinds of so-called organic cures that I was referring to.

Now if you want to believe that the Cornell baking soda formula supercedes chemical fungicides, you just go ahead and see how well your roses resist BS. In the meantime, I will engage in practices (such as buying disease-resistant roses) that CUT DOWN ON THE NEED FOR SPRAYING--which was the point of my previous post. And I don't mean, cut down on spraying by learning to tolerate ugly BS-ridden roses. I mean, buying roses that don't get BS or only get it a little bit once in a while--that is how you can cut down on the need to spray. But until a whole new generation of disease-proof roses are created, I honestly don't see how fungicide spraying can be completely eliminated. It can only be cut down on by exercising good judgment and wise choices --such as, in searching for and growing only the roses that rarely get BS and therefore rarely need any remedial action.

Buford, I know what you mean. I had to do some long hours of searching to find roses that rarely or never needed spraying, and like I admitted, I still have a few that are much less disease-resistant than I want, but I do love those roses, so ......... Sigh!

Kate

The following was stated: "#1: many rose growers have serious BS problems in their gardens, despite their good garden/rose-growing practices. If they go fungicide-free, there is only one possible outcome: roses devastated by BS. Your advice to them is a guarantee that their roses will suffer serious harm from BS."
---------------------------
H.Kuska comment: this thread is not about going fungicide free. It about "Organic fungicide that works".
--------------------------------

Concerning your point #2. Yes, I did not comment about some/many parts of your post because I did not have a problem with those parts. I commented on "In other words, quit looking for the magic (organic) cure. There is none--except for some good judgment and careful choices."

You did not say some organic methods do not work under some conditions. You said: "there is none-- except....".

How can you say none when I posted reviewed scientific papers that say there are?

---------------------------------
The following statement was made: "I honestly don't see how fungicide spraying can be completely eliminated."

H.Kuska comment: I feel that would make an interesting thread to many new readers and I could (and have in the past) contribute some literature on that point. This thread is about using organic fungicides. I assume that by saying "organic" most readers are assuming the intent is "non-toxic". This is why I posted the Brooklyn Botanical Gardens quote and link.

Gee I've completely eliminatated fungicide spraying in my garden. . Sure I have some blackspot but I can live with it. I grow mostly disease resistant varieties but don't feel I've given up anything except my weekly spraying.
I got over my perfect leaf phobia long ago.
Gave all my pesticides away and an trying to find a buyer for my almost new tow behind sprayer with a four foot wand.

Hey guys Paul Zimmerman is on facebook and a few years ago I asked him about cleaning up BSed leaves. He said he doesn't do it because it doesn't change anything. I mentioned in another forum my Octavia Hill rose is in the shade..and I live in the PNW and it does not have one leaf with BS. I am all for disease resistant roses. Less chemicals is the answer

It's obvious that the disease resistant roses are the way to go. Unfortunately, I was a religious sprayer. So I am just this year discovering that many of my roses are not disease resistant. I'd love to hear from others in a similar climate on which roses are very disease resistant. I think I'll start a new post on that though. I appreciate all of your thoughts.

Hi teka, I'm a bit north of you, but the roses I have identified as resistant are:

Reve d'Or - I've NEVER seen blackspot or any fungal disease on it.

Crepescule

Roseberry Blanket (a great low growing carpet rose, better than a KO, IMO. I now have one that is sporting a white color and I'm going to try to propagate it.

St Patrick (yellow HT) gets some boitritus, but not BS.

Sophie's Rose (Austin) gets some PM, but not BS

Teasing Georgia (Austin) gets some BS, but does not defoliate.

Teas, most of them do very well. Mine had a small BS outbreak early this spring because the weather was so weird. Actually it may have been anthracnose, but they've been fine since then.

Really appreciate everyone's experiences! I've been growing roses in Asheville (Western North Carolina) for about 8 years with varying success. I do not spray chemicals, but I do follow the Pat Henry of Roses Unlimited (Laurens, SC) calendar for amending, as well as her rose-planting formula. Over time, I've found a few roses that are almost BS free ( very few leaves affected); Paloma Blanca, Prairie Sunrise in the Bucks, Bremer Stadmusiken in the Kordes (which I think has been renamed to one of the Fairytales?), and Westerland, also a Kordes. The Polyantha Borderer rose does crazy well for me�some BS but not enough to ruin the look at all. Until this spring I would have put Mystic Beauty and Quietness on that list, but they were both attacked terribly hard in late April, to the point of near total defoliation. I am thinking it is weather related, so will try to baby them along and see how they might recover this year or next. I'm glad to hear that other people do not pick up the BS leaves. I actually got so frustrated in early May that I vacuumed under my roses with a small shop vac, laying the nozzle on it's side which worked well enough that I didn't get mulch, just leaves.
Also had an attack of aphids like I've never seen, and that was on new Awakenings, but spread to others. I got that under control with soap and veggie oil, and now suspect from looking on the web that I had over-fertilized the first year roses, and made them too attractive to the pests.
I keep several roses that do get more bs than the ones I mentioned, because I love them and they either don't defoliate much or I have them where their legs aren't so visible. I know this contributes to BS overall, so I may have to rethink keeping some of them.
Not to sound like an ad for RU, but because i live two hours away, I buy all my roses there. I usually pick up, but have had several shipped to good result. Always own-root, but never bare root. They have an extensive list.
I am always looking for recommendations for roses that can tolerate going back and forth between hot and cold in the same week, drought one summer, monsoons the next, record cold winter followed by record warm. I think many of you know the drill!

Pamin, I wonder if you thought of getting some ladybugs when those aphids showed up?

---"When leaves fall on the ground I rake them into ground to recycle them and use them for mulch. I've not found any problems with this"---

It depends on whether you want to get rid of the black spot or just let it have its way, there is no real inbetween.

If the bs is on the cane the fungicides with kill it. If you do not get rid of the leaves, as best as possible, then any efforts to get rid of bs are a waste of time.

To use such leaves as mulch is just plain silly.

I soak, my bushs and the ground around it, I do not piddle around with just spraying, with Serenade. The black spot goes away.
I do make a special effort spring and fall, whether or not I had, had, bs the year before, when the rose has no leaves to drench the canes.
But I do use a wet-dry vac. to suck up the leaves around the roses, especially late in the year.

If one wants the choice of roses one grows to be controlled by black spot then get the supposedly resistant ones, but if one wants to grow in one's garden, what ever roses the one wants, then make an effort to defeat the black spot and ignore the nay sayers that make excuses for not being able to control black spot.

I have taken to soaking my new roses in Serenade as roses I got from supposedly top rank nurseries have been the main reason I have had re-infections.

Teka- if you want to beat it you can, and don't let any who do not want to make the effort to defeat it convince you other wise.

Sadly up here we have a large public garden with roses but it is run by volunteers, and they have the ultimate way to get rid of the black spot that slowly infests the garden every so many years.
Rip the old ones out and put new roses and new soil in.
Not the best method.

This video may be a "rose club meeting filler" if a speaker does not show up.

On the right side there are other videos that sound interesting.

Here is a link that might be useful: link to Serenade fungicide video