The only logic I can see behind the idea is aspirin is salicylic acid, hence "acidic". Perhaps spraying with something acidic helps change the pH of the foliage sufficiently to help inhibit fungal germination? Remember those who promoted spraying foliage with vinegar, buffered with baking soda, to prevent diseases? I'm not promoting either idea as I'm not convinced they work nor can be done without damaging something. I'm not about to try it, either.

Reminds me of the Miracid fad years ago. I can't imagine spraying with aspirin will have any effect on disease, but by all means try it for yourself.

At least the Miracid would have fed the plant a bit, perhaps too much nitrogen, but at least it was a feeding. Aspirin?

katyajini: no doubt you entered "aspirin" in the search box for the rose forum, here.

I don't have time to look up the articles posted here and in scientific journals, but aspirin has a known effect on plants aiding in their resistance to many things. As a plant hormone many plants have high levels naturally not just willow. Henry has posted some here references in the past concerning its use as a fungicide and general "protectant". Search under "Salicylic Acid". For me the question is how well it's absorbed through spraying and if that's even necessary for it to have a beneficial effect. I don't use it myself as I spray very seldom.

Apparently boric acid will also help.

http://agris.fao.org/agris-search/search.do?recordID=RU2016001211

The full article is in Russian, but you may find the graphs useful.

http://agroproblem.soil.msu.ru/images/2015-3-26.pdf

Now that water shortages are becoming more common, one may want to keep in mind that salicylic acid may help there also.

https://czasopisma.up.lublin.pl/index.php/asphc/article/view/838/628

This is why I love you folks...so much valuable info! henry_kuska thank you very very much.

vaporvac: I dont like to spray either, too much work. But black spot was very bad for me this season, worse than its ever been. It made me so scared. Exploring every possibility I am coming across.

I might just try this aspirin thing once I learn a little more. People are doing it for their tomatoes all over the place.

katy, I have sprayed with baking soda and horticultural oil, I just don't have the time this year, so no judgement call from me! It's used for plants all the time. Give it a try.It doesn't work by changing the PH, but by helping with resistance so you could still use something else such as baking soda or sulphur and perhaps have better results.

Katy, you might also experiment with watering with crushed aspirin instead of spraying, in the event that spraying with it might produce issues with the leaves. In any case, we will be waiting to hear how this works (or does not) for you.

I'm thinking about watering cuttings with an aspirin solution. Willow water, which some use to stimulate rooting, has salicylic acid in it. It may help with rooting and might work as a fungicide. Worth a try. I wonder about the safety of spraying with the stuff because it might not be any healthier for you than breathing in a fungicide. So I'd use a respirator even with this.

Do we know if salicylic acid is bee-safe?

"Aspirin can also cause harm to the bees if they get in direct contact with the plants."

https://alovegarden.com/does-aspirin-help-plants-grow/

A cute little article, but poorly written for details. For example, the picture shown of aspirin is enteric low-dose, but it clearly states to only use uncoated aspirin without specifying the dosage, unless I'm mis-reading. Also, the comment above is not clear if the damage to bees is from being directly sprayed with the solution or just landing on a plant that has been sprayed. I suspect the former, but who knows. Since we do know that the pathway for salicylic acid is as a defense mechanism, merely watering the plant with a dilute solution may work just as well and avoid the problem.

This has become such an interesting thread! Amazing contributions, thank you!

I want to try aspirin but at this stage what would be a good experiment or simply beneficial? If a rose has already developed black spot would aspirin retard the spread for example? Or is it meaningful only before onset of disease? Then if I want to apply via roots (which is a great idea) what would be a good concentration to use? The soil is going to bind some of the aspirin I am sure. I do have a few ailing roses and aspirin might help them but I cant think of a way that would say unambiguously that it was aspirin that did it. I want to think for a few more days, If anybody has any thoughts please share!

Very interesting thread. This article suggests that salicylic acid (ie. Aspirin) surges naturally in some plants as part of a defense mechanism against fungi and viruses. Seems like this was how the discovery was originally made.
https://www.google.com/amp/s/www.newscientist.com/article/mg12917501-600-science-aspirin-helps-the-garden-grow/amp/

This is all too "Jerry Baker" for my comfort.

I'd be very cautious about taking to heart anything found between the covers of "New Scientist" magazine, since it has been criticized for its "scientific illiteracy" by many authors. I quote:

New Scientist was criticized by science fiction writer Greg Egan, who wrote that "a sensationalist bent and a lack of basic knowledge by its writers" was making the magazine's coverage sufficiently unreliable "to constitute a real threat to the public understanding of science". In particular, Egan found himself "gobsmacked by the level of scientific illiteracy" in the magazine's coverage.

I recommend sticking with proven technologies whose outcomes are known.

Google Scholar includes what articles cite each published reviewed scientific paper. For example the first paper cited in Stephanie 's link has been cited by 327 more recent reviewed scientific papers:

Salicylic Acid: A Natural Inducer of Heat Production in Arum Lilies ...

https://science.sciencemag.org/content/237/4822/1601.fullby I RASKIN - ‎1987 - ‎Cited by 327

The 327 cited papers are at:

https://scholar.google.com/scholar?newwindow=1&client=avast&um=1&ie=UTF-8&lr&cites=2590545782954638274

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

If we go to one of the citing papers:

Title: " Positive effect of salicylates on the flowering of African violet"

we find that it has been cited by 66 more recent reviewed scientific papers:

https://scholar.google.com/scholar?cites=1753338591994615763&as_sdt=5,36&sciodt=0,36&hl=en&newwindow=1

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

Paul, thanks for the reality check on the New Scientist plus it’s an outdated article with at least one questionable ref. As a scientist, I should do better. I searched with my university’s Web of Science search engine to see what is known more recently. There really isn’t a lot known on the topic of salicylic acid helping plants fight disease, but a couple articles show some interesting links between salicylic acid and a plants ability to fight infection. I am not sure spraying aspirin on our roses will help, although I don’t think testing it will hurt. More research needs to be done to flesh this one out.
https://www.sciencedirect.com/science/article/pii/S0885576517300437
https://www.ncbi.nlm.nih.gov/pubmed/22968829
And a review article.
https://www.sciencedirect.com/science/article/pii/S016894521400096X

The following was stated: "There really isn’t a lot known on the topic of salicylic acid helping plants fight disease"

======================

H.Kuska comment: I presented the Google Scholar results. I feel that my search indicates that in general a lot is known.

If the statement was meant to refer to only mildew and blackspot on roses, the following is the latest that I have found:

https://link.springer.com/article/10.1007%2Fs11103-018-00818-2

Using your find command, you will find 8 hits for salicylic acid.

I remember "Messenger" being touted as a plant growth enhancer. This was followed by some talk of a 325 mg Aspirin dissolved in 2 gallons of water doing about as much, but being a lot cheaper. I did think the "Messenger" did do something positive, but I never tried the ASA. These both were watered in or drenched.

Henry, thanks for pointing out the Neu et al. 2019 article. Very nice study using rose leaves to determine genetic stress response to powdery mildew and black spot! Interesting that the salicylic acid pathway was up-regulated in response to blackspot fungus but not powdery mildew fungus, at least in what they describe as the “susceptible rose cultivar” ‘Pariser Charme’. https://www.helpmefind.com/rose/l.php?l=2.4655.0 I wonder what a disease resistant rose’s gene profile would have looked like in response to blackspot and powdery mildew? Too bad they didn’t use a very resistant variety as a control, but it was an expensive study so I understand keeping it to one rose strain. It does look like the Germans are funding rose research though, which is great :-) In the study they state, “PR1 is one of the primary marker genes for the SA-mediated defense response, but its overall function is not yet clear.” When I said, not a lot known, I was referring to the biochemical pathways of salicylic acid in plants. They don’t seem to know exactly how it works, all of the pathways, and how they connect. But yes, I agree they definitely know salicylic acid pathways are up-regulated in many plants as a stress response. It also doesn’t seem clear that adding salicylic acid to the leaves of plants will help the plants fight disease or at least I could not find this in my admittedly brief searches, but maybe someone has shown this? I am a microbiologist working in a lab that studies microbes in ocean sediments so I don’t know much about the plant pathogen literature, making it harder to navigate, but I understand all the techniques in the Neu et al. study, since they are using many of the same ones we use to study bacteria using methane as a food source at the bottom of the ocean.

Stephanie, I normally only post advanced papers like the Nue paper on the Rose Hybridizers Forum. In this case no one has responded there.

http://rosebreeders.org/forum/viewtopic.php?f=2&t=56190&p=69250&hilit=neu#p69250

If you put the word aspirin into the Rose Hybridizers search function you get 59 hits.

http://rosebreeders.org/forum/search.php?keywords=aspirin

Henry,
Thanks for introducing me the the Hybridizers form. I created an account so I can peruse the contents. My account is under my last name Connon. Yes that is a better place for science talk :-)

I have not given up on trying spraying or pouring aspirin solution. I am trying quite a few things on my roses, I dont want to add an unknown (aspirin) to the mix right now. And I dont have scores and scores of roses to use as subjects, Just 13 right now. And not all of them are susceptible to diseases....Next season I will try as the vegetable growers I read about are doing it. Either treat 1 or 2 or half of your plants or all your plants that you know are vulnerable with aspirin and compare what happens with the other half and previous seasons.

I agree life is too short to try fringey things when there are more reliable options. But lets not forget a body of anecdotal evidence becomes data. Very often scientific research is propelled by something that is observed repeatedly either by a person in everyday life. or other scientists in the course of their work. Trying something you heard about anecdotally is OK sometimes specially if you are running out of options!

I turned to this forum when, for whatever reasons, the disease pressure on my roses was high and I wanted to see what others experience or expectations or opinions were for various preventive measures. And so much good discussion and information has comes forth.

A very recent publication:

Title: "Effects of exogenous salicylic acid on the resistance response of wild soybean plants (Glycine soja) infected with Soybean mosaic virus"

https://www.tandfonline.com/doi/full/10.1080/07060661.2019.1641750?scroll=top&needAccess=true