I confess it didn't do much for me...but I guess consistency is all with any spraying programme...which is where I always fail.

This is a published, reviewed 2015 scientific research paper regarding its use for mildew on roses.

http://www.nzpps.org/journal/68/nzpp_683800.pdf

Trish, are you spraying only milk, or milk diluted with water? If diluted, what is the ratio? Thanks, and keep up informed on progress.

Diane, I'm diluting t with 2 to 3 parts water. One source said 2, and another3, so I've gone down the middle!

I am not entirely sure I would be celebrating from that experiment, Henry - stems and leaves, in lab conditions are not living plants in garden conditions ...and I think there are questions regarding efficacy across a whole season as well. If mildew is a real problem, then the milk treatment (I used skim milk, diluted 1:10) is, at least not harmful and can, in some cases, have a mild benefit - but, although I didn't manage to do this every 2 weeks, by August, PM was back in force on ZD, Sweet Pretty and Pomponella..

eta - I note your dilutions were much lower than mine, Trish, so keep us updated as I would not be averse to making another attempt.

The following was stated: "I am not entirely sure I would be celebrating from that experiment, Henry"

H.Kuska comment. Yes, it is not all positive. A complete scientific paper is not meant to be a company advertisement (if it would initially read that way, it would be the job of the reviewers and the editor to insist on a balanced report if they were aware of any negatives).

Hopefully, when the full paper is available, the reader is able to make an informed judgement as to whether the method meets his/her goals. When only the abstract is available, one can normally e-mail one of the authors for an "e-mail reprint" or look it up in a nearby large university library.

Camps, at a cursory glance, I understand this paper refers to milk fats as providing the antifungal properties. In this context, spraying skimmed milk wouldn't help much.. I haven't properly read the paper but I wonder if what we see here is mechanical action of fats on the tissue surface which provides some preventive effects (similar to other methods involving oils) rather than fungicidal properties which woud provide some curative effect also. In any case, until something is discovered / invented which is either fully systemic being able to be translocated internally to new growth or fundamentally helps the plants immune system, fighting PM during the active growth stage will remain a problem in a garden environment.

Btw, I'm surprised that Dutch greenhouse growers still use (only?) Milban on their roses. I wonder why they don't use some more modern fungicide maybe together with Milban in a rotation cycle. Maybe there are enbironmental and legal restrictions on what they can use or maybe newer fungicides are not recommended for use in greenhouses due to rapid resistance buildup?

"The experiments presented here show that combining AMF with SBO had a synergistic effect on PM control on roses and tomatoes."..........."One explanation for synergy might be that AMF and SBO appear to have different modes of action. A scanning electron microscope study carried out on wheat PM after application of AMF and SBO showed that SBO treatment was associated with bursting and release of PM cellular contents, while AMF caused distortion and plasmolysis of fungal structures."......................................"AMF, which is derived from milk, contains only the antifungal fat component."

That would provide some curative effects (I wonder if other oils do the same). This is still non systemic action as explained in the paper (which I have now read more carefully). I wonder if 'AMF' can be substituted by clarified butter in a home remedy.

BTW, in my limited, very unscientific, trials I have found that combining some fungicide like myclobutanil or tebuconazole or even bupirimate with a light solution of a good quality highly refined mineral horticultural oil (summer oil) seems to provide better control than applying the fungicide alone (which of course should not come as news since oils have been used for fungal control since a long time ago). Tissue damage can be minimized by keeping the oil solution weak (up to 5ml/lt) and spraying in the evening. In my climate PM occurs when the temps are not high enough for good quality hort oils to be a real issue with regards to tissue damage. Regardless, I have stopped regularly spraying for PM and only intervene curatively if and when the pressure is very high (about once or twice per year) and only on specific plants.

When a harmless spray for blackspot appears, then I will be celebrating. PM (on roses), in my climate, is often a physiological effect of dryness at the roots or lack of ventilation (but is debilitating on my curcubits), and consequently, the problem can be remedied with careful placing and irrigation, but both BS and cercospora are disfiguring syndromes which I have been reluctant to put up with since, far from growing out of it, the roses seem to be worse affected, earlier in the season as years go on. I admit, I have never been organised about removing infected leaves which are either on the plant or off it and it seems to accumulate. For many years, I was fairly convinced that it was a given in the (non-industrial) parts of the UK until banishing all those prissy floribundas, HTs ( my clutch of Harkness roses were the absolute worst offenders apart from the cast-iron Many Happy Returns) etc and going back to the motherlode - wildlings and those hardy, huge ramblers, none of which seem to get even a blemish of BS...but I miss Cardinal Hume and Masquerade badly..and would dearly love to have Austrian Copper..and Mutabilis is perfectly horrible, sadly

For powdery mildew I suggest trying to strengthen the rose immune system against mildew with salicylic acid (aspirin as substitute) or hydrogen peroxide to see if that would be sufficient.

http://onlinelibrary.wiley.com/doi/10.1111/tpj.12966/abstract;jsessionid=226249B08282882EC8F4432DDFA8E74D.f04t04?userIsAuthenticated=false&deniedAccessCustomisedMessage=

Thanks, Henry, I've seen your posts on this, and mean to give it a go.

There's almost zero info usable by the average home gardener in all these links that are being posted, almost automatically whenever the term 'powdery mildew' is encountered in a thread, regarding either tangible benefits or, most importantly, field methods of application regarding hydrogen peroxide and aspirins. Unless and until such literature becomes available, which is first the job of biochemists and then of agronomists not geneticists, I wouldn't bother to do a thing. This is the kind of basic research stuff that, while certainly seeming to have some positive potential implications, looks tailor made to produce anecdotal 'evidence' by well intended but uninformed gardeners performing unscientific 'experiments' and pronouncing this or that as 'useful' or 'useless', and not well intented commercial agents marketing miracle potions. I remember vividly a person belonging to the first group which used to frequent these forums and who had an obsession with 'experimenting' while gardening in alkaline clay...

I certainly hope some of this genetic based research produces some concrete results with tangible benefits at some point but, until then, the only use I can see for these scientific research papers for an unscientific audience is broadening one's encyclopedic knowledge.

I do not understand why someone would conclude that understanding how a plant can be helped to resist disease using its own immune system would be characterized as "genetic based research".

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My father graduated with a BS in Agriculture from the University of Nebraska in 1921 (delayed by World War I service). His first job was what now would be called a State Agriculture Agent (they had a different title then). He was surprised to find that many farmers did not want to learn about the details of growing plants. His feeling was that one would be a better farmer if one understood the botany of plant growth. He then taught high school agriculture.

I feel the same about rose growing.

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An pertinent (in my mind) article published by the Department of Agriculture is given below:

http://agresearchmag.ars.usda.gov/2003/dec/plant

Of particular interest in the above article to this aspirin sub tread (I feel) is the following:

" Plants have always had some means to defend themselves; it's just that some don't recognize their microbial attackers in time. Spraying salicylic acid or certain other compounds snaps them to attention and puts their defenses on high-alert against future attacks.

Plant scientists first encountered the phenomenon, called systemic acquired resistance (SAR), in the 1930s."

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The link below is to a Google search (note, not Google Scholar) using the keywords:

"salicylic acid", plants, and defense

https://www.google.com/webhp?hl=en&authuser=0&gws_rd=ssl#q=salicylic+acid+plants+defense&newwindow=1&hl=en&authuser=0&start=10

Nik, what harm could salicylic acid do?

It is not the matter if it could do some harm or not (which I don't know about, it might well do in high dosages). It is the matter that it might not provide any benefits to you or any other amateur who cares to try it, so the word is spread that it does not work while the real reason for it not working was, for example, it wasn't applied properly. Then the whole thing is discredited in the community when it shouldn't.

Or it might go the other way, you apply some, you think you notice some effect, while that was due to any other of tens of factors (wishful thinking amongst these) which were not properly controlled in your unscientific 'experiment'. Then the word goes round that it is a miracle potion, merchants take advantage of it (and me and you) until many people try the same with no effect and the thing is discredited again. This is NOT the way to go about these matters IMO and Henry, as a scientist, should know better than encourage the average gardener to perform these 'experiments', until and unless the scientific community comes up with field applicable results and proper usage instructions (along with properly prepared concoctions).

nikthegreek, this is a forum. If you have specific questions about application procedures that you cannot find answered in this forum ( a search of the rose forum results in 70 hits):

http://www.gardenweb.com/gardenweb/query/aspirin/topic=roses

or in a standard Google search ( https://www.google.com/webhp?hl=en&authuser=0&gws_rd=ssl#newwindow=1&hl=en&authuser=0&q=aspirin+plants+use

please ask them.

For some reasons every time I see these types of arguments it reminds me of this joke:

Flea Experiment:

A prominent scientist conducted a very important experiment. He trained a flea to jump upon giving it a verbal command ("Jump!").

In the first stage of the experiment he removed the flea's leg, told it to jump, and the flea jumped. So he wrote in his scientific notebook: "Upon removing one leg, all flea organs function properly."

So, he removed the second leg, asked the flea to jump, it obeyed, so he wrote again: "Upon removing second leg, all flea organs function properly."

Then he removed the last leg and told the flea to jump, and nothing happened.

He did not want to take a chance, so he repeated the experiment several times, and the legless flea never jumped. So he wrote in conclusion, "Upon removing the last leg, the flea loses sense of hearing."

The few links I visited out of the mulitude that come up through these searches just support what I have been talking about. A total mess with noise inundating reality. Especially in GW, most of the threads have been initiated by HK btw. I personally have no specific questions because I'm not getting to be part of HK's noisy 'experiment' campaign. I will be waiting for scientific concensus and workable field proven instructions. And, btw, I don't care about maintaing flowers in the vase nor about enhancing the vigour of my tomato plants. I think I have made my points clear earlier so I personally do not find any use in furthering this discussion.

I really cannot understand the 'heat' in this argument. We're not talking about a possible cure for cancer that would maybe dupe desperate people into parting with thousands of dollars, but merely a possible help for PM costing next to nothing, and doing no harm. Is it simply boys butting horns?

I am going to continue with my milk spraying, and see what happens.

I will report again in a few months. By the way, I have a degree in Statistics and Applied Maths, which I only mention as not to be seen as some wishful thinking imbecile!

Wishful thinking is a normal human trait not limited to imbeciles.

Oh Nik

Performing an, even minimally, controlled experiment in one's garden is quite complex, so I guess very few people bother to do it.I certainly couldn't and wouldn't.

Firstly one has to perform it on a reasonably large number of copies of the same plant and divide this set into 2 for control. Ideally more copies of different suceptible plants should also be used. This is were most attempts to experiment fail for lack of suitable subjects. Secondly one has to grow these sets of plants under similar conditions preferably close-by. Having them in pots is ideal in this respect but then that poses the problem of the experiment not being realistic enough. Thirdly one has to use a reasonably reliable method of assessing the results and correlating them statistically (e.g count number of leaves affected). Even if one does all those things one will have obtained just one set of results related to one application regime. Trying multiple application regimes multiplies the complexity. All these (which are the minimum required) are pretty difficult to do by an amateur gardener so chances are they will not be done. Not doing these leaves things open to matters of chance (climatic conditions and other environmental factors prevalent at the time of the experiment), unreliable human memory ( I think this time last year some plants had more/less mildew evident) and subjective evaluation which is were wishful thinking (expectation bias) comes into play.

Nik, I agree 100% on all the points you have made. I have read many of papers in the links that HK has posted. The papers touch on issues that most of us would like solutions for but more often than not, I find them to be, as you put it, 'encyclopedic knowledge'. Would be great if they could be applied in a normal garden environment but I am reluctant to try. In most cases, these are studies are carried out in a controlled environment and, I believe, could be potentially damaging if applied eg. http://forums2.gardenweb.com/discussions/3383207/mildew-research-mineral-and-vegetable-oils. Although in this case, I don't see any danger in spraying milk. That is why I appreciate titian1 10b Sydney reporting on this experiment. Look forward to hearing the results. Maybe HK could report back on the results of his experiments too.

Sharlene

The following was stated: "Maybe HK could report back on the results of his experiments too."

H.Kuska comment. I grew about 1000 roses in a no spray garden (I say grew because I am now in advanced retirement, age 78). I mainly reported on my experience with hydrogen peroxide in the Rose Hybridizers web page. A search of that site gives 126 hits with the search term "hydrogen peroxide".

I used to have a web page of my own with considerable rose information, but the company (Road Runner) discontinued providing web pages.

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An attempt to utilize either aspirin or hydrogen peroxide to trigger the immune response comes under the topic of Integrated Pest Management .

http://www.rose.org/rose-care-articles/integrated-pest-management-what-is-it/

" IPM works in a progressive manner. You start with the least harmful methods of control for man, animals, and the environment collectively. The use of natural controls is the first item on the list. If they fail, then you progress to controls with the least harm to man, then to the least known to harm to animals and beneficial insects, and finally the environment. Also in this process is consideration of cost effectiveness for short and long term controls. No need for an expensive, labor intensive program to remove a small percent of the population."

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A normal Google search with the keywords "integrated pest management" and "salicylic acid" gives the hits (about 16,500, they only list 291) listed at the link below:

https://www.google.com/webhp?hl=en&authuser=0&gws_rd=ssl#newwindow=1&hl=en&authuser=0&q=%22Integrated+Pest+Management%22+%22salicylic+acid%22+

If you add the keyword "roses" to the above Google search, you get about 147,000 hits (they only list 228). (I do not understand how adding an additional keyword can result in more hits unless they include hits where 2 of the 3 search terms were found.)

Similar searches with the keyword "salicylic acid replaced with "hydrogen peroxide" gave 52,100 and 440,000 hits respectively.

If one includes both, one gets 10,700 and 17,600 hits respectively.

If one is interested in "integrated pest management" techniques, I suggest that you also consider the use of silicon as discussed in the link below.

http://forums2.gardenweb.com/discussions/1586199/silicon-induced-resistance-against-powdery-mildew-of-roses-caused?n=12

A new review (still in press) has just appeared:

http://www.sciencedirect.com/science/article/pii/S0304423815301746