Whether this would help significantly in a bad area for blackspot (such as NJ) and on highly susceptible roses, nobody knows. Controlled trials have shown that milk spray does control powdery mildew disease. (Any kind of milk.)

However, I've lived through many cycles of home remedies being proposed for rose diseases. Many of them work on powdery mildew but none of them, so far, works well on blackspot in conditions of high disease pressure. So I'm skeptical about milk, but we'll see. Please report back in late summer if you try it.

The pH of cow milk is 6.4 to 6.8, slightly acidic ... must be other factors in milk to stop BS. Either really acidic, below 4 like vinegar, or alkaline above 8 like baking soda worked well. My dusting with whole-grain corn meal, pH 8, worked really well, plus keeping the surface soil dry and alkaline.

Also ms642: Are your roses grafted on Dr. Huey, or are they own-roots? Own-roots can adapt to acidic conditions, either from pine mulch (pH 4.5), acid soil and wetness way-better than grafted on Dr. Huey.

See below link for other ways to control BS, the organic way:

Myself, I focus on selecting roses that are more disease-resistant--then I don't have to spend much time worrying about spraying, organic or nonorganic.

Lots of different ways to do things in a garden. What works for you may not work for someone else, and visa versa.

Kate

However, it's NOT good to spray milk on the ground, the salt in milk prevents the plant from getting calcium from the soil. Here's a quote from the research below on how salt inhibits fungi.

"Previous plant research shows that relatively low amounts of sodium chloride applied in the field to barley plants inhibits their ability to transport calcium from the roots to the shoot portions by interrupting the active transport of calcium into the root xylem (Lynch & Lauchli 1985)."

People don't realize that the German chemical giant Bayer makes other crop-control products, and NOT just for roses. 94 million acres of corn are planted with seeds treated with pesticides. There's also the Oberon-insecticides spray for corn.

There's a book about fighting cancer written by an M.D. with a brain tumor. He wrote about growing up in France and watching farmers nearby spraying their corn field. There are 3 studies that linked bee decline to Bayer Pesticide. If our crops are sprayed, and if our flowers are sprayed, then how will the bees survive?

With the news of Angelia Jolie's double-mastectomy, I was checking on pesticides and cancer risk, and found a large study of 30,454 farmers' wives in Iowa and North Carolina, and here's the study's conclusion:

"The authors found no clear association of breast cancer risk with farm size or washing of clothes worn during pesticide application, but risk was modestly elevated among women whose homes were closest to areas of pesticide application."

Here's a description on how the spores are transmitted: "The fungi that cause black spots overwinter on infected leaves that fall to the ground. The following spring, just as new leaves are unfolding, the fungal tissue in the leaves on the ground ripens. The surfaces of the spots split and minute, needlelike spores escape. The spores are carried about by wind and if they land on new leaves of a susceptible host they may germinate, penetrate the leaf tissue, and start a new disease cycle."

One safe way is to dust the ground with whole-grain corn meal, pH of 8, that would inhibit the spores. Corn meal has zero salt, so it's better for the roots than milk or baking soda - both have salt.

Corn meal also supplies nitrogen to the soil, and it hosts Trichoderma fungi, the beneficial fungi that inhibits the pathogenic black spot species. Whole grain corn meal works best.

Some folks dust a fine-layer of wood ash, pH 12, ON THE GROUND. It's OK if your soil is acidic, and the roses' root are buried deep in a cold zone. My Mom in acidic soil, Michigan put leaves around plants, then sprinkle a fine-layer of wood ash over leaves. The leaves cushion the plants' roots from being burnt, and the rain washes down very alkaline wood ash to neutralize the acidic leaves.

Woodash NPK is 0-1-3, high potassium, plus 15% calcium, and all trace elements. My Mom used that as fertilizer for her acidic soil.

Wood ash burns surface root, so it's not safe for warm climate. High pH above 7.5 inhibits the spores on the ground. My soil pH is 7.7, so spores can't germinate over the winter. I have zero black spot on my 52+ own-roots this spring, and insignificant late fall.

In my last house with acidic clay (1/2 hour away), and mulched with wet leaves (pH 4.3 to 5), or acidic pine bark (pH 4.5), the spores germinate over the winter, and I had the worst BS in the spring.

So yes if you try certain methods let us know how
they work in NJ...

I had about 1000 roses in northeast Ohio and in about 5 years of no spray I feel that blackspot was under control. (In late fall many roses had some blackspot, but I assume that is part of nature's way of removing the leaves in preparation for winter.)

@mori1, you said the best thing to do would be to take care of my soil. What procedures can I take to take care of the soil?

It would help to know the names of the varieties that you are growing and where you are in NJ (county is fine).

I won't go into the issues of organic controls for roses in NJ here, it causes too much agita. Let us know if the milk controls work for you. East coast conditions are very different than other parts of the country. If the milk doesn't work, contact me, and I will do what I can to help.

The best way to avoid the use of any fungicide, organic or synthetic, is to grow disease resistant varieties.

Same with results with:

Baking soda method
Greenlight rose defense / Neem oil
Cornmeal spread under rose bush
GreenCure
Safers garden fungicide
Serenade Garden
Wilt pruf

I know a lot of people like to stay with the oraginc remedies but how are the fungal sprays that you can buy from like home depot?

Also, Have any of you ever tried miracle gro water soluble rose food? If so how effective is it with the growth of roses?

Let me start with something I see right away. The stem with the red rose on the right. Is that growing from the same source as the pink rose? If so, that red rose and the stem is rootstock doing something we call "suckering". The pink rose is grafted onto another rose, Dr. Huey, which is used as rootstock. You want to dig down and find the source of that stem, rip it off and scrape off any remaining stem. If allowed to continue, eventually you will have all Dr. Huey and no more pink rose.

As for fungicides, Bayer Advanced Disease Control for Roses, Flowers, and Shrubs is very effective. You can find it at Lowes if you decide to go with a synthetic fungicide. It is mixed with water and sprayed on the leaves, you will need a tank sprayer to apply.

Fertilizer: Yes, I have used Miracle Gro (or alternatives). They are good for fast action. In my opinion, a better choice is Espoma Rose-tone (or Plant-tone, or Holly-tone), you can find 5lb bags at HD or Lowes. They are a NJ company. The products are blends of mostly organic materials, and help to add/retain organic materials in the soil in addition to fertilizing the plants.

If you click on "My Page", send me an email. I am in Monmouth County, but there is a Consulting Rosarian who lives in your area who can help.

The OSU research suggests that while these organic options can suppress Mildew, they are pretty much useless when dealing with Blackspot. What it boils down to is this: remove plants that suffer badly from disease and replace them with varieties that are inherently more disease-free, or resort to commercially available fungicides to suppress disease*. Mulching and manuring the plants will likely have some effect in suppressing Blackspot, but I doubt you can eliminate the disease if you are trying to grow varieties known for their disease problems in a climate where environmental pressure for promoting disease is extreme.

I recommend removing the worst offenders and getting healthier varieties.

*The "better living through chemistry" approach becomes less and less acceptable with every passing year, as we learn more about these environment-altering chemicals and their effect on other living things. While rose fungicides are nowhere near the top of the Most Toxic Garden Chemicals list, neither are they benign, and using them should be considered with great care.

Evaluating Natural Products for Control of Black Spot Disease on Roses

Ekaterina A. Jeliazkova, University of Wyoming, ekaterinaj.pubs@gmail.com

Clarissa Balbalian, Mississippi State University

Tess Astatkie, Nova Scotia Agricultural College
And
Pamela Collins, Mississippi State University

There was zero bees nor butterflies in my rose garden back then with Bayer spray. I don't see any bees nor butterflies at the rose park nearby with 1,200 roses, they spray every 10 days. Also the increased risk of cancer with pesticides, esp. breast cancer.

Grafted-roses on Dr. Huey are LOSE-LOSE in my zone 5a: If I plant them at ground surface, they die, and Dr. Huey take over. If I plant them 4 to 6" below ground, Dr. Huey declines ... he hates being buried deep in wet clay. I dug up, and Dr. Huey shrank.

I posted ways to grow roses healthy without spraying in the Organic Roses Growing. See the link below:

The newly bred roses by Paul Barden, Kim Rupert (Roseseek), and Robert Neil Rippetoe are all very healthy as own-roots.

I use fungicides, I have leaves, and I have plenty of bees and butterflies in my garden.

I use fungicides, I have leaves, and I have plenty of bees and butterflies in my garden.

Salt in fertilizer drives down both calcium and potassium, necessary for the integrity of plant cell to protect against fungal invasion. I wrote a post on how calcium and potassium defend plants from disease .... both lacks in acidic soil. My major is in Computer Science, minor in chemistry helps with my experiments with roses. See below link for info. on calcium and potassium for roses:

I keep the soil surface dry and alkaline with horse manure mulching. I can induce BS on any rose just by dumping acidic alfalfa meal (pH 5.7), pine bark mulch (pH 4.5), rotten tomatoes (pH 4), or acid fertilizer .... fungi grow best at acidic to neutral pH.

There are many disease-resistant OWN-ROOT roses like Francis Blaise, which I got on sale from Roses Unlimited in NC for $10 few summers ago. Roses Unlimited has a sale either 1st week, or 2nd week of June for $8 per gallon of own-root.

Below is Francis Blaise, taken last week, zero BS even in late fall, despite my 40" of rain in zone 5a. Paul Barden, Kim Rupert, and Robert Neil-bred roses are also very disease-resistant like Francis Blaise rose.

"Our results demonstrate that essential oils of English thyme and ‘Scotch’ spearmint hold promise as biopesticides for control of black spot on roses as an alternative to chemical fungicides."

The only other significant point I got from the abstract is that, assuming you have access to "essential oils of English thyme and 'Scotch' spearmint" (anyone? don't stampede, please), you have to spray it WEEKLY.

I can't say I want to spray anything WEEKLY--ugh! But it sure would be nice if someone found a natural "fungicide" like thyme or spearmint.

Kate

Dr. Huey seems to do very well in my yard, which is mostly hard red clay (of course I've amended, but even before that). Everything is subjective.

Earlier in the paper they stated that in Mississippii they had to spray the above fungicide mixture every week.

"Frequent applications of synthetic fungicides are necessary to effectively prevent and control this disease.
Our 4-year observations at the Mississippi State
University Veterans Memorial Rose Garden as well
as observations of producers in Mississippi showed
that to control black spot, ornamental roses need to be
sprayed every week with commercial fungicides. In
2009 for example, 36 fungicide applications (from
March to December) were required for the prevention
and control of black spot at the Veterans Memorial
Rose Garden."

In Table 2 the treatments with the same lower case letter are stastically equivalent for the last week of the 6 week study period. Thus those with a "d" are as good as the commercial fungicide mixture.

H.Kuska comment. Earlier in this thread I posted a reviewed scientific paper that spraying with Banner-Max every 2 weeks (plus other commercial fungicides every other week and every week) did not give complete control.

This is a corrected page. I originally said Bayer. I should of said Banner-Max. Banner-Max is Popiconazole based. Bayer is Tebuconazole based. They are from the same chemical family but the fungicide properties are probably different to some extent. Sorry, my error.

Does anyone know of a reviewed scientific paper that does report complete control?

And there is a huge difference between complete control and naked roses with black spot.

When I do spray the bayer every 2 weeks (or when I did Daconil every week), I did not have black spot. Without it, defoliation. If I'm lax or can't get to spray because of weather conditions, then yes, I will have a breakout of BS.

I recommend that one not attempt to extrapolate to other conditions.

Perhaps you should also scold Strawberry Hill for extrapolating her experience to other conditions. Or maybe for just saying complete untruths.

Almost everything in my yard gets black spot. I feel confident that there is very high pressure here and any product that works here will work almost anywhere. So I will continue to recommend to people who are interested in the effectiveness of the Bayer Spray. Other people swear by Banner Max or other sprays. I don't have any agenda, just to share experience with other rose growers. That is what this board is about and what it's for. I have learned more from people who are simply telling me their personal experiences than I have from reading all the papers you have posted here.

I do hope that we haven't scared the OP away by overwhelming with "information", that certainly was not my intention.

It hurts to spend hours researching on what works, what doesn't work, doing experiments, and got shot down. Is this forum to encourage people to grow roses, or for ego-freaks, snipers, and control-freaks?

I only share with what works for me, and post pictures of what works for me. Just because I do things differently rather than spray, doesn't give you grounds to attack me like that. I speak the truth about my gardens. My motto for posting is "I speak for myself, and not for others." What works for me may not work for others.

Bayer may work for you, but didn't work for me, so please don't force that on me.

Are we here to find out the truth, to share one's experience, or to shoot people down just because my zone 5a or soil behaves differently?

Whatever I did wrong in my last house, or whatever I do right in my present house, I share my experience to help others NOT to give up roses like I did.

Roses get a bad rap for needing chemicals, who wants to grow roses? Many times I just want to quit growing roses and feel discouraged by the sarcastic attacks. At least I am brave enough to post pictures of my clean roses, rather than attack people behind their backs.

I am a Mom with a 10-years old daughter, I don't have time to spray, and I don't have time to attack others like MichaelG did to me. That's not nice, and I don't respect that.

I'm in zone 5a, where the bud-union from Grafted roses can be damaged by cold winter, Yes, I did spray with Bayer in my last house, it didn't work. Call me a failure for not spraying right, but I won't tolerate attacks on my character and personal experience, just because I share successful organic ways in my present garden, which doesn't work for everyone.

Everyone's soil and climate are different from each other, there's is no point of attacking me either out of jealousy or because you want to promote Bayer.

"Tebuconazole did not control blackspot."

The above is from a reviewed published scientific paper.

I usually wait until I actually see some blackspot--then I spray once and, if needed, about 10 days later again. That usually takes care of it in the spring. Summers here are too hot for BS, so I don't worry much about it until fall when the temps drop into the BS range again--in which case I may need to spray a time or two again..

I agree with Buford. Anyone who uses Bayer Advanced Disease Control and still has BS and defoliation is doing something wrong. It is very effective and it does not kill bees and butterflies in my garden.

Kate

In my last house of acidic clay, I also used Bayer-3-in-1 with insecticides.... way too much in heavy clay. I think the heavy dose of fertilizer zapped the roots of my roses. Go ahead and pick on what I did wrong 15 years ago, I was just a newbie.

I ask that you don't make personal attacks on me just because I use organic ways successfully in my present garden. That's bullying, suppressing the truth, and a big discouragement in growing roses.

I wish I could wait and see but if I don't get an early start then forget it. IF I don't stay on schedule then I pay for it. Once it hits about 85 and up then I don't worry about it. So far so good, leaves have some BS and a lot of rose slugs damage but it looks better then it has in the last few years. Of course that could all change as we have three more days of rain. My soil so water log.

H.Kuska comment. Baking soda is NaHCO3. The Cornell formula is KHCO3 plus a very specific combination of spreader-sticker additives in very specific quantities. See:
http://www.hiagritech.com/pressreleases.htm

"Several years of research resulted in some significant and surprising discoveries. "The research demonstrated the ability of bicarbonates to effectively inhibit and kill mold spores and determined that potassium bicarbonate was 25 to 35 percent more effective than sodium bicarbonate (baking soda)," says Horst. The research further indicated that a spreader-sticker mechanism was required in order to control and maintain the effectiveness of the bicarbonates. "Without a spreader-sticker," adds Horst, "You don't get complete coverage of the leaf which is necessary to prevent or cure fungal diseases."

During the years of research many spreader-sticker systems were tested, including the use of horticultural oil as an additive. This resulted in better control of the solution and proved more effective than water and bicarbonates alone, unfortunately the test results also showed that horticultural oil as an additive had many negative characteristics.

Negative characteristics of horticultural oil as an additive to bicarbonates include:

Repeated use for several weeks causes phytotoxicity

It results in an oily residue building up on the leaves, fruits and vegetables

There is an occasional visible crinkling of the leaves

The oil separates rapidly from the water making application difficult

The use of such an oil may not be ideal from an environmental standpoint; it could increase the hydrocarbon loading of the air and in ground water

For these reasons and others, horticultural oil was rejected as a spreader-sticker. In order to find a safer, more efficient additive, more than 350 spreader-sticker systems were evaluated. Highly effective spreader-sticker additives were discovered which increased the efficacy and reliability of bicarbonates for use on ornamentals, vegetables and fruits. Additional research was done on a wide variety of plants and quantitative results were determined for a broad spectrum of fungal diseases. Ultimately, a combination of spreader-sticker additives in very specific quantities was found to be significantly more effective than all other alternatives. "

Buford, diane, and I are only referring to the Bayer Advanced Disease Control for Roses, Shrubs, and Flowers. And we recommend it only to posters who ask for a fungicide to spray on their BS. We do not "promote" it--we simply tell those posters the truth--that the Bayer fungicide is effective in our garden and many, many posters on GW over the years agree with us that it is very effective. If I did not know how often and how many posters have posted on this forum that the Bayer fungicide works for them, I would not recommend it to posters asking for an effective fungicide.

Strawberry, you are right--you have every right to experiment (and report) any organic methods you want in your garden, and everyone should respect your right to do that. But please do not answer posters questions as though you were a recognized expert in the world of rosarian experts. There are several posters on this forum who do rate as "experts"--but most of us are not. We may be "experienced"--which can give us a limited degree of expertise--but we are not "experts." And neither are you--so please stop preaching to newbies as though you were an expert. By all means, offer information when it is solicited, but that is very different than implying that you have all these answers to problems that rosarians who spent their entire careers studying them could not come up with or agree on. You are not smarter than everybody else in the rose world--but neither are most of us.

Please do keep on enjoying your roses and the experiments you like to conduct. That's fine. Just do not confuse them with having advanced degrees in research and professional recognition from other professionals and experts in the rose world.

I hope you don't take this post as a put down--I'm trying to be helpful.

Kate

Are you here to encourage rose-growing, or to shoot me down, to accuse me wrongly of "being the expert", or to slander me just because I do things differently from the sprayers?

I always back what I post with others' research, or my own experiments in my garden, for the sake of truth and validity. If I care for the environment and tried the organic ways successfully in my present no-spray garden, do I deserve attacks for that?

If organic disease control works for you, great. It does not work for everyone.

"Sprayers" are not out to get non-sprayers.

As Buford said, if organic disease control works for you, great. There is nothing to argue about.

It does not work in my garden.

Kate

I have a lot of Black Spot in the garden (and a lot of naturally clean roses), but it really doesn't usually do much. It's like my roses grow out of being hurt by it with age. Most of the leaves don't even turn yellow at all.

But I do get some defoliation that is too big a problem on a few, so I go with the Bayer product to knock down the infection. That seems to work nicely for me.

I also use fish foliar sprays (mixed with milk, because I liked the results when I started that) every few weeks, and I always spray (like wash off, literally) the roses' foliage once it's hot enough in the year that they like that, etc. Who knows what all contributes to total health as far as fungus goes? The foliar feeding or watering is really for other reasons in my garden, but it might help keep the bad fungus down. I couldn't say :)

The use of any fungicide, whether it is organic, or inorganic, has a cost. It's up to the individual to determine if those costs are worth investing in and exposing themselves to. But, each decade has resulted in stronger, healthier and more floriferous rose plants in many cases. Comparing the HTs and floribundas of the fifties with those of the sixties, seventies and later, you can see the improvements in their health and performance.

I have observed that newer varieties of roses have frequently been healthier in my climate, and much easier to grow without intervention. I realized that will vary significantly by rose and climate, but I honestly believe that is something worth each rose grower looking at. Many older rose varieties have been removed from my collection to be replaced with ones which don't spot, mildew or rust nearly as easily. You can honestly reduce, if not eliminate disease issues in many instances with a shovel. Replace the truly bad offenders with those which are happier to be where you are. You may not be able to have the perfect "pretty face" you are after, but you can frequently have a much easier to grow, healthier plant under the pretty faces you have. Kim

A few years back I heard a long time gardener speaking and he noted that in all of his years living in this town and all the various weather patterns, every year is unique.

We have had some really bad peach leaf curl going on, I have the sprayer, the spray and planned on spraying. But ran out of time. Nothing got sprayed.

Odd thing, we have no peach leaf curl. At least none on any of the trees I have checked. Go figure....what was different. Half the rain and skipped the fog this year. Now I did do some hard core pruning and thinning in the past years, so that might have had an effect.

Next year we might have rampant leaf curl (I still plan on spraying)

So this year if something that has always been clean or bad, remember that before you decide it was one garden technique or another that caused/cured it, maybe what is more important is if you can replicate the same result year after year. If not, it might be mother nature playing with you, just like my peach leaf curl.

H.Kuska comment. It is my impression that there are a small number of posters (and mainly the same ones) who repeatly post that the Bayer fungicide works for them. I try to save the blackspot posts and in a quick look through I feel that there were not threads that support the statement: "many, many posters on GW over the years agree with us that it is very effective".

Perhaps someone can give the link to at least one thread that supports the "many, many" statement.

----------------------------------------

Also no one has pointed to a controlled scientific study comparing tebuconazole to other available fungicides that supports that concept ("very effective"), and the supporters just ignore scientific evidence when the conclusion says that in that study: "Tebuconazole did not control blackspot.".

Another point that the apparently "only tebuconazole" advocates in this forum do not address is that they do not recommend rotation of fungicides to prevent the blackspot from developing a resistance to it. Many of the blackspot articles that I read recommend rotation. (I suggest a Google search with the three key words: roses blackspot rotation).

Example:

"3.Chemical: Chemicals such as chlorothalonil (Daconil), myclobutinol (Immunox), tebuconazole (All-in-One Rose and Flower Care), and neem oil (Fungicide 3) may be used to control black spot. Most of these should be sprayed at a 7 to 10 day interval. For best control, rotate two or more chemicals to prevent the fungus from building up a resistance to one chemical. Spraying should start as soon as leaves appear in the spring and continue into the fall until frost."
httphttp://johnston.ces.ncsu.edu/gjuly09/
----------------------------------------

I say the Bayer spray works because it does. And Daconil works, but you need to spray it every week. I'd rather use the Bayer and spread out my spraying to two or more weeks. That lessens my exposure and the amount of chemicals in the yard.

As for 'small number' of posters who say the Bayer works, well I'd say there is only one poster who has said Bayer doesn't work.

Again, I don't care what anyone else does with their roses. But if people ask for advice I will share my experiences. And if I see something posted that does not seem right, I will also speak up.

I would not spend $30 a year and make a special trip to Lowes just to get the Bayer spray concentrate, have a backpack sprayer and fill it up every 2-3 weeks and carry it around (it weighs about 40 lbs filled) my yard and spray my roses if it didn't work. I don't need a scientific paper to tell me if it works or not, I can see the results for myself.

H.Kuska comment. the above sounds like the spraying only with tebuconazole is effective unless one is "more fussy". i.e. effective is a relative term.

The following thread discusses rotating fungicides.

The link below is one attempt to create such a database.
Kim's point and not rotating fungicides merge because practically, by not rotating tebuconazole , one is contributing to the creation of a new strain of blackspot - one that is resistant to tebuconazole.

"Seven isolates of Marssonina rosae (imperfect stage of Diplocarpon rosae) elicited different blackspot disease expression among 39 Old Garden Roses In laboratory tests. 'Felicite Parmentier' (Alba), 'Mme. Hardy' (Damask), 'The Bishop' (Centifolia) and 'Rosa Mundl' (Gallica) showed no symptoms. 'Cardinal de Richelieu' (Gallica), 'Hermosa' (China) and 'Leda' (Damask) were the most. susceptible showing a culuvar ratings ", mean of 2.86 or more. The Wayne variant was the least virulent, causing susceptible reactions on only 46.1 % of the roses. The Hinds varIant was the most virulent and caused symptoms of 89.7% of the rose plants tested. The remaining five variants caused disease on 69.1% to 79.5% of the plants."

2) Henry asked for a link showing the superiority of Bayer Disease Control (tebuconazole) to other synthetic fungicides. That would be the Emma Gachomo dissertation. Please see the series of photos showing how leaflets age after inoculation with blackspot and treatment with various chemicals. Unlike other fungicides, tebuconazole kills the fungal body growing inside the leaf. She did not test propiconazole (Banner), which might be about as effective. A reduced-risk strobilurin fungicide was also highly effective, but this product is available only in large quantities for huge $$$.

3. Tebuconazole (ingredient in Bayer) was found ineffective against blackspot in the Hagan (1991) study. This is an anomalous result. They mention a previous study that found the chemical highly effective.
There must have been something wrong with the material they used, which was Lynx brand tebuconazole, or their mixtures. In my own multi-year experience, Bayer Disease Control sprayed every 14 days provides almost complete control of blackspot. It has been much more effective than triforine (Rose Pride), myclobutanil, and various non-synthetic sprays that I have applied at 7-day intervals in the past.

Title: "Efficacy of triazoles and strobilurins in controlling black spot disease of roses caused by Diplocarpon rosae"

Authors: E.W. Gachomo1,2, H.-W. Dehne1 & U. Steiner

Published in: Annals of Applied Biology, volume 154, pages 259-267, (2009).
E.W.

"Abstract
Black spot disease is an important disease of roses with worldwide occurrence. It is caused by Diplocarpon rosae, an ascomycetous fungus and its control relies on fungicides. The effects of strobilurins and triazoles on D. rosae development within the host and on disease symptoms have not been well studied. Strobilurins completely inhibited germination of conidia when applied protectively 1 week before inoculation or on the same day with the inoculum. They were, however, not effective in eradicating the disease when applied after the fungus was established in the host. Triazoles reduced the germination rate of the conidia when applied protectively and they inhibited disease symptom development when applied after the fungus was established in the host but before symptom expression. Application of triazoles after symptom development suppressed further development of the disease, but in the case of treatment with myclobutanil yellowing and defoliation still occurred. Post-infection application of triazoles led to the apparent breakdown of subcuticular mycelia, intercellular mycelia, and hyphae in the epidermal cells, while the effects of strobilurins were limited to the subcuticular mycelia. Triazoles were more effective than strobilurins because they are more systemic."

From the Discussion Section.

"Our results show that the two groups of fungicides are
effective at different stages of the fungus development and
can therefore be incorporated into a disease management
programme. The strobilurins are suited for pre-infection
applications, while the triazoles are suited for postinfection
applications. As application of myclobutanil after symptom development did not hinder the yellowing and subsequent defoliation of the diseased leaves, it can be used in pre-infection treatments but before the appearance of symptoms, while tebuconazole can be used even after symptoms have become visible. The development of
the fungus within the host is influenced by the prevailing
weather conditions (Gachomo & Kotchoni, 2007).
Therefore weather conditions that delay the development
of the fungus may allow for the prolonged use of
certain fungicides. The fact that different rose cultivars
have differing degrees of resistance (Knight & Wheeler, 1978; Castledine et al., 1981; Walker et al., 1995; Wiggers
et al., 1997; Drewes-Alvarez, 2003; Blechert & Debener,
2005) should be taken into account, thereby giving the
growers a very flexible disease management plan depending on the cultivars that they grow."

In the body of the article: "Table 1 Effects of different fungicides on the development of Diplocarpon rosae and black spot disease on rose leaves, when applied 3 and 10 dpi and observed 10 and 14 dpi, respectively" There is a + in the "Symptom Development" column for tebuconazole.
(dpi means that the plants were treated with the fungicide 3, 7 or 10 days after (post) inoculation).

"Black spots with a diameter >10 mm developed on
untreated plants. The infected leaves turned yellow but
the leaf tissue around the black spots remained green
forming ‘green islands’. Infected leaves dropped off the
plants beginning 15 dpi. There were differences in the efficacies of fungicides when they were applied curatively.
The symptoms observed were classified according to the
disease scale given under materials and methods, and results summarised in Fig. 4.
Post-inoculation application of both triazoles 3 dpi, and
of tebuconazole 7 dpi inhibited disease expression, while
post-inoculation applications of trifloxystrobin and pyraclostrobin led to varying degrees of disease severity. The effects of the four fungicides on disease symptom development at different times before and after inoculation and the corresponding fungal developmental stages in the
untreated plants are summarised in Fig. 4."
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H.Kuska comment. Unfortunately, the disease scale results are not given in Figure 4. One can estimate the disease severity for tebuconazole when the fungicide is applied at 10 days after disease introduction as 3 to 7 % from the small graph in Figure 4. No data were presented for longer time periods but the slope is positive.
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Regarding the Hagan study being "an anomalous result". According to Google Scholar that paper was cited by 11 more recent papers. I looked at them and I did not see any that were challenging the results. In fact the Hagan group cited it in March 2011. (J. Environ. Hort. 29(1):25��"28. March 2011). ""Previously, foliar applications of tebuconazole have been shown to control Entomosporium leaf spot on photinia (2) but not black spot on rose (9)."

H.Kuska comment: Please notice the editor and reviewers allowed that statement to be published in 2011.

In the Gachomo paper the Hagan study was not challenged (not even mentioned). In the thesis the Hagan paper was mentioned but not discussed to my satisfaction. "In previous studies Hagan et al (1991) had shown that weekly sprays of tebuconazole at the rates of 20, 40 and 80 ppm gave only some modest reductions in the disease and that the weekly applications of the fungicide at all these rates were equally effective in controlling the blackspot disease. Although the application of tebuconazole at the above mentioned rates gave a season long reduction is disease ratings compared to the untreated control, heavy leaf spotting and some leaf shed was observed on plants treated annually with this fungicide (Hagan et al 1991)."
Please notice that Hagan group used a lower dose rate then the Gachomo group. What dose rate did you use?

Yes a reference to Peterson's 1989 paper was mentioned by the Hagan group. They explained the difference as "probably" being due to a difference in the disease pressure. How did you rule out your personel findings also being different due to the difference in disease pressure?

Whether you and your papers like it or not, I have been using Bayer fungicide for 4-5 years now--BECAUSE IT WORKS. I don't need a paper to tell me if it works. I look at my roses which stop having BS problems after I spray them. That is my test.

Would other fungicides also work? Possibly. The ones I have tried in the past didn't work very well. Are there fungicides I haven't tried? Yes. But I don't recommend fungicides (or other products) that I do not have personal experience with.

I learned about Bayer fungicide years ago from a rose grower in Florida named Pete. I'm glad he introduced me to Bayer fungicide--though I still maintain adamantly that buying roses that are very disease-resistant is the best line of defense. I have roses in my garden that almost never get sprayed because they almost never get BS.

If it works in my garden, why should I change to a different product?

Kate, the pragmatist rather than the theoretician

buford your personal experience is with your variety of roses in your soil conditions exposed to your climate conditions with the strains of blackspot that are in your garden.
I recommend that one not attempt to extrapolate to other conditions."
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I am a scientist attempting to explain what scientists have determined about the ability of fungicides to control blackspot using controlled scientific methods. Scientists have determined other properties of tebuconazole that you may want to consider in deciding whether to continue using it. One example is its ability to "stunt" your roses. " With elevated drench rates of tebuconazole on roses, however, deep green leaf color, noticeable chlorosis around the leaf margin, reduced leaf area, and shortening of the shoot internodes was occasionally noted (Hagan, personal
observation)."

Of course it works in Buford's garden. That is what Buford said.

A poster asked if we could recommend an effective fungicide. Buford and I recommended that fungicide that works effectively in our gardens.

So why do you keep on arguing about it? It works in our gardens--of course we would recommend what works in our gardens. I never recommend something that does not work for me. Are you saying you recommend products that do NOT work for you? Of course not. We recommend what works in our gardens. Of course. Of course. Of course. (How many times does that have to be pointed out to you before you hear it?)

And I might add, my roses sprayed with Bayer fungicide have NEVER exhibited "stunting," "chlorosis around the leaf margin," "reduced leaf area," NOR "shortening of the shoot internodes." I don't know what in the world your scientists are doing with the fungicide to produce those results, but if they occurred when I used Bayer fungicide, I would QUIT using Bayer fungicide--since that would not meet my criteria for an "effective" fungicide.

But I have NEVER had those results from using Bayer fungicide in my garden. It has always EFFECTIVELY stopped the BS infection with NO such negative consequences.

Now tell me I am lying. Is that what you really believe? How insulting can you be!

(NOTE: This is a disgusting thread because of your quarrelsomeness, and I am leaving it. Go find someone else to go quarrel with.)

Goodbye.

Kate

Kate

Kate, darlin' - you put your finger right on it.

I'm not sure what Henry's point is. I though he hated all chemicals and didn't want anyone to spray anything. But it sounds like he's trying to get us all to spray more and different chemicals. I can't keep track.

I have to go now and report back to the President of Bayer as to my efforts in promoting their products :)

My experience with Bayer Advanced Disease Control is the same as buford's and diane's--except that my region doesn't have as much BS pressure as their region does, so I can get by spraying considerably less than they do.
I usually wait until I actually see some blackspot--then I spray once and, if needed, about 10 days later again. That usually takes care of it in the spring. Summers here are too hot for BS, so I don't worry much about it until fall when the temps drop into the BS range again--in which case I may need to spray a time or two again..

I agree with Buford. Anyone who uses Bayer Advanced Disease Control and still has BS and defoliation is doing something wrong. It is very effective and it does not kill bees and butterflies in my garden.

H.Kuska comment: please notice the "Anyone who uses Bayer Advanced Disease Control and still has BS and defoliation is doing something wrong."

Henry's arguing can be annoying, but IMO it is constructive. He thinks clearly and of course is extremely well informed.

Henry,

Regarding spray concentration: I don't understand the units you cited. If you care to make the conversion, I use the labeled concentration of Bayer, which is 0.75 fl oz to a gallon. The product is 3% tebuconazole.

Regarding stunting: I observed stunting of shoots in a mini-trial of propiconazole (Bonide version of Banner) applied to one side of a Marie Pavie plant. I have not noticed any stunting with Bayer tebuconazole. My roses grow quite vigorously. Stunting was observed with "elevated drench levels," not with spraying per directions.

Regarding disease pressure in my garden, based on comparing reports of blackspot resistance and effects of non-synthetic sprays from various parts, blackspot pressure is worst here in Appalachia and in the mid-Atlantic states. Olga in Maryland and Diane in NJ have reports similar to mine (very few repeating roses are resistant).

Now, Henry, you want to cite my comment that if the Bayer doesn't work, you are doing something wrong. I stand by that. Strawberry Hill said that she used Bayer spray and her roses were 'naked with black spot'.

Now you are trying to link my comment to a stunting problem. Apples and Oranges. Like michael, I've never experienced that.

There are many things you can do incorrectly to not have the Bayer work properly. You could not have the correct mixture (too little and it would be ineffective, too strong, could damage the roses), you could spray when it's too hot, or too cold, or too wet, or too windy. All of these could change how the spray works.

But if you do it correctly, it works. And it works quite well. Otherwise michael, kate, myself and many others (there are rose growers that exist outside of GW), wouldn't use the product, we'd find something else.

In my garden, every rose gets some black spot. That includes my OGR's, KO and The Mayflower.

Below are 3 HT's which were last sprayed the first week of May. Not one spot!

H.Kuska comment. Your comment was not linked to a stunting problem. It pointed out what you said ("using quotes"). You did not say you MAY have done something wrong IF your blackspot conditions were the SAME as mine, and your rose varieties were the SAME varieties as mine, etc.

As my computer trainer DH says 'the odds that a computer makes a mistake are vastly dwarfed by the odds that it's operator error'.

I'm not sure what you have against Bayer or why you keep harping on first it's danger to the environment and now to it doesn't work and will harm plants. Don't use it. And trust me, if it really doesn't work, no one will use it.

The active ingredient in Fungonil is Chlorothalonil. The 1991 Hagan group paper found Chlorothalonil to be: (H.Kuska note: for some reason, the cut and paste will not work with this paper so please read the paper and fill in this section.)

Because of the possibility of tebuconazole to cause tebuconazole resistant blackspot, I strongly recommend the rotation with a fungicide with a different mode of action.

No one has mentioned that the Bayer tebuconazole label only allows three sprayings per year when blackspot is present. I assume this is because of the above possibility.

H.Kuska comment. One does not divide the world into black and white only type thinking. No one has said that tubuconazole never works under any conditions. The Hagan group paper made that clear with the quote that I presented earlier concerning a prior paper that reported that it worked. Even the German paper found blackspot in the "One can estimate the disease severity for tebuconazole when the fungicide is applied at 10 days after disease introduction as 3 to 7 % from the small graph in Figure 4. No data were presented for longer time periods but the slope is positive. " at the higher concentration of tebuconazole that they used

I hate using chemicals so for the most part I never touch them. BUT I have broken down and did the deed when things were way out of control. When I do so I do rotate what I use so as not to saddle myself with a type of black spot that nothing will work on. That's just biting off your nose to spite your face.

And after 4 (or more) years of spraying with only Bayer fungicide, I find that the blackspot has NOT become resistant to Bayer fungicide.

I really am beginning to think you are talking about a different Bayer product than the rest of us are. Are you perhaps referring to the Bayer 3-in-1 product ? Or maybe the Bayer 2-in-1 product? Or maybe some other Bayer product? If so, they are NOT what we are talking about when we refer to Bayer Advanced Disease Control for Roses, Flowers, and Shrubs--which is what we use.

You can make all the assertions you wish, based on a paper study. They will still be WRONG, based on the actual roses growing in our gardens.

Kate

The label does not recommend rotating with another fungicide, which many other fungicide labels do recommend. This suggests that Bayer is not worried about home garden use of tebuconazole leading to resistant fungi and consequent loss of that market. However, it is of the type to which resistance could develop.

Shame on you, Henry. That is not what the label says. You have twisted Bayer's words to make them supposedly back your misapplied argument.

What Bayer says is that 3 sprayings may be needed to wipe out the current infection (I always have found that 2 sprayings are sufficient.) Bayer is NOT warning consumers to limit spraying to 3 times a year. That is WRONG, WRONG, WRONG. It is simply claiming that it won't take more than 3 sprayings to get rid of the infection you have today.

Now if you don't spray after those 3 sprayings, the rose could later get re-infected. In which case, it should not take more than 3 sprayings to wipe out that later infection. (In my garden, 1 or 2 sprayings are all that is needed to wipe out an infection outbreak.)

I'm serious, Henry. A "scientist" who misreads that badly can not really be trusted. I'm also very concerned that you are giving out this mis-information to newbies who have no basis for deciding yet which view is more trustworthy.

Just give it up, Henry. You are just digging the hole you are in deeper and deeper.

And if you had not insisted on dragging this out so needlessly and scornfully, I would not have directly impugned your scientific integrity--but really, this has become outrageous and needs to stop.

Kate

"Do not apply more than 6 applications per year in all states except New York, and do not apply more than 3 applications per year in New York State."

Whenever I visit California, I come back feeling that all of my roses are stunted.

I make this statement because some people have claimed that tebuconazole does not cause stunting of their roses. My question is how do they know? Do they grow the same rose side by side with one not sprayed with tebuconazole?

One's tebuconazole sprayed rose may not be stunted, it may be stunted 1 %, 5 %, etc.

Stunting is a known property of tebuconazole. This is scientific fact. Unless you are interested in Queen of Show it may not be of importance when you set up your spray program, but it may be of interest to someone else with different goals and blackspot intensity.

Again, poor reading skills. That direction is for professionals using professional strengths to spray grass--like the putting green at your golf course. Or for when you take out your airplane and spray your ACRES of plants out there in the fields--as in professional agri-business (farmers).

It has nothing to do with amateur home garden use, following the directions on the home garden product to spray a couple dozen roses.

And compared to California roses, everybody's roses look somewhat stunted, whether we spray or not. All that proves is that roses grow good in California--but we have all known that for a long time now.

You just can't let go, can you.

Kate

In the Ornamental Section the following appears: "Do not make more than 4 applications per year at highest rate."

"Guidelines for Developing an Effective Fungicide Spray Program for Wine Grapes in Maryland, 2012"

"Strobilurin-resistant strains of powdery mildew are also losing sensitivity to sterol-inhibiting (SI) fungicides, particularly Rally and Elite (including generic formulations of tebuconazole). SI resistance occurs more slowly, and growers may able to compensate for a few seasons by increasing the application rate (up to the label rate), spraying at shorter intervals, or switching to a different SI. The more frequently any SI material is used, however, the higher the level of resistance that is likely to develop."

But you are still confusing professional strengths used at professional rates and in professional quantities with limited amateur home garden use.

Kate

Bayer recommends 1.5 tablespoons of the concentrate added to 256 tablespoons of water (1 gallon). 2.9 % concentrate is 2.9 gm tebuconazole per 100 grams of solution. 1.5 tablespoons of the concentrate were added to 256 tablespoons of water (1 gallon). This is a dilution factor of about .0058. So now one has about 0.18 grams in 1000 gms of solution. I made several approximations in the calculation. I feel that we can say that the Hagan group top concentration is probably within round off error of the Bayer recommended concentration.

We do not have to make the conversion from grams per liter to ppm as the Gachomo Thesis has done it for us ("In previous studies Hagan et al (1991) had shown that weekly sprays of tebuconazole at the rates of 20, 40 and 80 ppm ....." ) , we see that the Gachomo group (by using a concentration of 100ppm) used a concentration 1,25 higher than the Hagan group.

H.Kuska comment. I am interested in the amount sprayed per rose due to concerns about both stunting of that rose and blackspot mutation on that rose .

Perhaps reviewing the thread that I linked to earler will be useful in seeing that blackspot mutation could be a real concern.

"What you're doing by spraying more frequently is allowing resistant spores to increase more frequently with no competition from non-resitant spores. The spores are living organisms - they will attempt to mutate, to evolve, and to produce more resistant strains if they are only exposed to one threat. If this threat is introduced more frequently, then that resistance will occur much faster and with greater magnitude."