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Solution for Mold on Fig Cuttings

Hello,
Long-time reader, first-time writer, here anyway. I have been a lurker on this forum for a few years and I've noticed that moldy cuttings are a serious issue, so I decided to share a method to help inhibit mold on cuttings.
 
A little background on me first. I studied chemistry, worked in research labs for about 15 years, currently work in the food and drink industry (writer, product maker) and caught the fig bug about 2 years ago. I live in Canada (southern Ontario) and currently have 18 fig trees. My friends call me Darcy.
 
One of the easiest ways to inhibit mold is to use a method winemakers have been using for a long time to prevent mold in wines, and that is to use Potassium Sorbate.  A solution of 0.1% Potassium Sorbate is very effective at inhibiting mold and much safer than using bleach or other harsh chemicals. 
 
This mixture would work well for cutting storage or when fig cuttings are wrapped in wet paper towels or kept in a damp environment (plastic bags). For shipping of cuttings, spraying them with the solution and allowing them to dry before mailing should be effective as well.
 
Here's how you do it: 
 
Simply take 1 gram of potassium sorbate and dissolve it in 1 liter of warm water. For the metrically challenged just take ΒΌ tsp of potassium sorbate and dissolve it in a quart of water. You can use the solution with perlite (or any other growing medium) as you would normal water. You can also keep it in a spray bottle. Once the cuttings have rooted you can just use regular water and it will wash out any of the potassium sorbate.
 
Just a note if you are using Pro-Mix or other potting soil with Mycorrhiza, the potassium sorbate will inhibit the growth of the Mycorrhiza fungus. 
 
Potassium sorbate can be found at the local homebrew / winemaking shops or ordered online. 
 
Hope that helps and if you have questions, I'm happy to answer.

Lone time wine maker here i use it to kill mold spores and wild yeast. Never even thought about that.
On another note. Did you know oxy clean is the exact same thing. Read a oxy cleanlable. Local wine shop sells a little 3 oz container for 5.99
doller store sells half gallon for five dollers. All it is is unrefined hydrogen peroxide. Thanks for the tip.

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  • sal
  • · Edited

My current procedure for inoclualting Grape Must is using Potassium Metabisulfite as opposed to Sodium metabisulfite.  To my understanding potassium sorbate is a stabilizer or used to kill excess yeast ? prevent recurrence of fermentation. I'm glad Figpig is in here because I currently use his protocol and @nycfig and my Mold issues have disappeared.

 I have to look at my equipment I wonder if Potassium Metabisulfite would do the same thing? Just curious because I don't have any potassium sorbate on hand.

@dsoneil

Welcome to the forum!!! I'm very interested in trying this on some new cuttings.
I typically scrub and spray a bleach solution on my cuttings. I let it dry after that i put them in damp Coir..

What is the need to wash out/off potassium sorbate after I spray my cuttings?

When potassium metabisulfite is added to wine (or water) it breaks down and produces sulphur dioxide (SO2) which pretty much sterilises the wine. Basically, the same thing chlorine does. Chemically, SO2 is harsh but is typically used in very small quantities (30 parts per million). I'm not sure what the effect of SO2 would be on fig cuttings, but I suspect it would be much like chlorine, best for washing, not good for watering or storing. 

Potassium sorbate just prevents fungi and yeast from reproducing, it doesn't actually kill them, plus it isn't harsh and a number of plants produce sorbic acid as a natural anti-fungal.

There isn't really a need to wash off the potassium sorbate, I just mentioned it because I use ProMix HP with mycorrhiza and potassium sorbate would inhibit it. So I'd be paying more for the ProMix HP, but not getting the benefit in rooting cups. 
Potassium sorbate has the benefit of beingsulfur dioxide gas

What about Starsan?  Dodecylbenzenesulfonic Acid - 300ppm and Phosphoric Acid - 780ppm

Starsan is usually what I use to clean my brewing equipment, but it is basically an acidic soap product. It would probably clean like bleach, but have no residual fungal inhibiting action.Starsan

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  • sal

Thanks for the tips Darcy.

I need some equipment anyway so Ill pick some up this weekend.

The old 10% bleach. 30 seconds soak. Works grate too. After 12 hours air exposure bleach is gone.

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