This is my second year spraying a very dilute raw (un pasteurized, unfiltered) apple cider vinegar on my pear trees at bloom time to prevent fireblight. Southern Bartlett always got some fireblight and would look ragged this time of year on account of this. It would never really get strikes. It’s resistant in that sense, but it did suffer. Last year and this year it has been completely clean. I’m sold that this is an effective preventative for fireblight, at least on a pear variety that already has some resistance.
The active agent is not the vinegar itself but the microbe that makes the vinegar. That’s why it’s important to use raw vinegar. The microbe grows in the sugary liquid secreted by blighted tissues. It then secrets an antibiotic that kills the fireblight microbe. The mixture I use is one tablespoon per gallon of water. Thanks.
When I see anything that looks even a little bit like a stem canker lesion on a prunus, I spray a much stronger raw vinegar solution on it. It’s way too early to be sure how effective this is going to be with fighting stem canker. But last year I was seeing the tale tale evidence on the trunk of my Mariana tree. I sprayed the trunk down. It’s still with me. Every now and then I see a lesion and spray it and it heals. We shall see. It may not be something that a commercial guy could do with a whole orchard, and it probably would not work with a variety with no natural resistance. But it definitely seems to help even with stem canker on plums.
I use that brand for my acid reflux, works most of the time. I use 2 tablespoons in 8-10 ounces of water, with a bit of honey to take a bit of the whang out of the vinegar. Sometimes I add a bit of cayenne pepper to the mix, too. To keep it from damaging my teeth, I drink the mixture with a straw.
Nice to hear that it works on fireblight, will keep that in mind. I use colloidal silver for personal use, since it’s an anti-bacterial and anti-viral, so I was wondering if it’d work on FB. Just a thought.
When it is that you actually do the raw apple cider vinegar spray? Before, during, or after the pear tree bloom?
Do you ever combine this with a regular tree spraying chemical routine? Such as just adding that one tablespoon per gallon to the sprayer tank along with the fungicide or insecticide mix.
It sounds like you just use it by itself but I thought abut using it along with my regular spraying.
Careful vinegar changes water ph and chemicals eg. Fungicide are mixed assuming your using standard water. I consider members such as @Olpea experts in this area. By lowering the ph you change the fungicide .
I was curious about why this works and looked a little more. (pharmacist in me) It explains why it can be used internally as well as on surfaces. I was surprised by the effect on blood sugar and candida, and might consider this myself. I understand that this is probably more than you want to know. The Use of Vinegar Vapor to Reduce Postharvest Decay of Harvested Fruit.pdf (170.8 KB)
These organic acids destroy the outer membrane of the organism cell wall, inhibit the macromolecular synthesis, consume the microbial energy, as well as promote the production of the antimicrobial peptides in the host cells. Also, the antifungal activity of ACV was explained in some studies through the fact that it inhibits that candidal adherence to the smooth surfaces and thus preventing its colonization and the ability to form an oral biofilm
Since it appears from the article that the important thing is that sufficient vapor remain in the air for at least several hours, and the efficacy increases with glacial (28%, IRC) acetic acid, and since glacial acetic acid is so pungent, I wondered how much vapor would be freed if one simply opened the bottle inside the chamber for a time. If, in real life, one could simply guarantee a “sufficiency” of vapor inside an old refrigerator with extra shelves to allow spreading out a lot of fruit at once, then it would become practical for us little guys.
But my apples don’t seem to spoil from the outside very much, so for me it might not matter. I do lose a fair number of pears, though. Need to remember that it would not accomplish the same thing as nitrogen-fitted CA storage.
I also wondered if a dilute vinegar rinse followed by a slow drying might not accomplish quite a bit too.
I thought this was interesting since they treated a variety of apples, and tested for aroma and taste of treated apples in addition to prevention of fungus decay.
I think one of the reviews subjected the apples to 24 hours of acetic acid/vinegar vapor, then vented them for 1-2 hours to let them “air out”, then stored them in refrigeration. Rinsed and vented were considered as options in one place I read.
On the very first link i posted i responded to Alan
I can only make an assumption the concept of vinegar being used to kill the fireblight bacteria started with articles such as this Canadian article released from The National Collaborating Centre for Environmental Health that reports “These organic acids are hypothesized to cross the cell membrane of bacteria where the release in protons (H+) causes the cells to die.69 As the growth of many pathogenic organisms are inhibited in conditions where the pH is <4.6, these organic acids, with a pH 2 to 3, are commonly added to foods as a preservative " See this link and then you will know about as much about it as i do. The concept is simple enough. There is no true research to back it up at this point. The article is speaking about bacteria and never about fireblight or fruit tree treatment http://www.ncceh.ca/sites/default/files/Alternative_Antimicrobial_Agents_Aug_2014.pdf .”
In your position i would spray copper pre bloom and use the vinegar if you need it after fruitlets develop. I wont use copper once the fruitlets develop. Copper is a heavy metal so i limit exposure as i can. I dont feel its harmful when sprayed once a year.