Home Remedy for Fireblight

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.


That was the kind of vinegar my sister-in-law convinced me to drink for good health a few years back. I lasted about two days and fell off her bandwagon.

Glad it has other use besides killing my taste buds :laughing:


When fireblight is particuarly bad i use vinegar Recurring Problem Pears Every Late Summer - #29 by clarkinks
It worked great for me but it was considered highly aggressive at the time and unproven but the trith was in 2014/2015 i didnt know a better way. @rayrose tried the same approach but the fireblight had progressed to far to fast. Great approach and please keep us updated.2016 Stone Fruit Diseases are worse on wet years - #16 by clarkinks
2018 Fireblight -conference pear? . 2013 , 2014 ,2015 were bad years for fireblight Late season Fireblight - #4 by clarkinks

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.

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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 .

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Clark is right. Most ag chemicals benefit from an acidifying agent. However not all pesticides are more stable in a lower pH solution. I was told Delegate insecticide is most stable at 7 pH solution.


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



That’s a lot of good information - pretty provocative. Might need to get you to explain a few terms, though.

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What is very dilute is? Could you please provide proportions?

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If anyone has a specific question about the articles, let me know in what part you read it and I will do my best.

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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.


Some really good information here.

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On the very first link i posted i responded to Alan

" 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 .”


@mamuang, interestingly, self-made sport drinks recipes often include vinegar. Widely considered to be very healthy.

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Healthy honeybees propagate mother vinegar in there hives as well as probably spread this to other blooming flowers


Thanks for the recommendation. I have a Conference pear that had fireblight last year. I have Williams pears which, so far, seem unaffected.

Two questions from a novice!

  1. I’m in France and the most common unpastuerised (home made!) vinegar is wine vinegar. Do you think that will work? I have not seen raw cider vinegar in our shops, but will keep a look out for it.
  2. Is the timing critical? Do you spray once the flowers are fully open, or as the buds start to swell?

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.