SaraJean asked a question about peroxide...
 

On the Beginner Discussions, Sara Jean asked the following question and I would really like some discussion about it:

This is just a general question for anyone that reads this and I am not meaning to hijack this thread in any way ... Can someone help me understand what the point is if a hydrogen peroxide soak for a sick orchid? I have read that it’s used to sterilize the root zone when repotting but I have never know it to be very effective at sterilizing organics. Inanimate objects, sure, and maybe some surface bacteria (good or bad) but it’s not a systemic and it’s pretty short acting. Is this just an old school hold over like ‘don’t fertilize your orchids when in bloom’? Similar to when we used to use H2O2 in surgery for wound care and debridements but don’t anymore due to it not really being effective and it increases healing time, yet people still use it at home. Or is there some science behind it?

I see this same peroxide vs no peroxide discussion over and over again. I don't use H202 anymore for wound care because of literature I've read that makes sense. It would be nice if the Bill Nyes of the OB could give a little education about H202 and orchids. Like fact based, not as seen on a YouTube video.

Please and thank you. :bowing

I'm not sure where you are seeing a recommendation for hydrogen peroxide soak, but I would consider it a very bad idea. Not only is it largely useless, but can cause extensive damage. It might seem like a valid idea for cleaning a cut or broken point in a root, but it can be translocated through the vascular tissue of the plant and cause an extensive area of necrosis, almost guaranteeing rot in the damaged tissue.

Having worked with drugstore-grade 3% H2O2, 50% industrial grade, and Biosafe Oxidate @ ~0.1-0.2% H2O2 application rate, I can provide some anecdotal comments backed by a small amount of science.

3% H2O2 is basically worthless as a disinfectant. The stabilizer in it is so weak that it completely decomposes within seconds of application, leaving behind a pool of water in which pathogens can multiply. Does it damage the few root hairs orchids have? Maybe, but I doubt it's significant due to the transient nature of the peroxide.

Some growers claim it is a good oxygenator of potting media. Yes, it releases oxygen as it decomposes, but that too is transient, and using a water breaker and watering heavily probably does as much benefit.

50% H2O2 is much too corrosive of anything metallic or organic.

Biosafe Systems Oxidate (a.k.a. Biosafe Disease Control) has a very weak concentration of peroxide, but it is stabilized with peroxyacetic acid, so it is a very good disinfectant, as it stays chemically active until it is dry. I used it extensively in my greenhouse in PA, as a general spray and as a repot cleanse, and I never saw any sign of phytotoxicity - no doubt due to the low concentration. It will corrode skin if you have contact with its concentrated (27% H2O2) form.

Agreed, PaphMadMan. I see that recommendation on and off from time to time here. I am NOT in favor of it, and think it's a bad idea. Pretty sure SaraJean feels the same way, but can't speak for her. I was looking for the science behind it, as her question posed, when giving the response of Oh HECK NO...Don't do that! Otherwise, it's a hard argument to make against someone whose friend does it, or it must be true because I saw it on a YouTube video.

---------- Post added at 09:54 AM ---------- Previous post was at 09:48 AM ----------

Interesting, and never heard of Biosafe Disease Control. Appears to be something I'd like to put in my "just in case" arsenal. Would that be something one could sterilize LECA with? I have several gallons of LECA that's barely been used, and seems a shame not to reuse. Of course, I throw away old yucky stuff.

What in the heck does one use industrial grade H202 for?

I related question is why was it recommended in the past? 8-10 years ago here on the forum, H2O2 was frequently recommended to treat crown rot. There was no discussion about whether this was good or harmful, and it was standard advice, and not only here. I did treat one crown rotted Phal with it back then, with no ill effects to the healthy tissue (I know that anecdotal evidence is not scientific proof. Could be that the bottle wasn't new and the H2O2 had already slowly transformed into mostly water... I don't recall if the plant survived the crown rot)

Yet another good question. Yes, why was it a frequent recommendation? I've never used it on a plant, and had stopped using it on my kids boo-boos around 25 years ago. From what Ray says above about the 3%, it sounds mostly ineffective, as opposed to being caustic to the plant. Hmmmmm.

I couldn't do without hydrogen peroxide anymore. Bleach is just as important for me.

Any scientific basis for that statement? I can't do without chocolate from time to time. That doesn't mean it's good for me. :biggrin:

Basically, I don't use H202 on plants or people anymore. Because in the last 20 years we've discovered it not only kills bacteria and "fizzes away" rot, but also destroys the good cells around the wound, whether human or plant. So it makes no sense to me to apply it to an already struggling plant, as it also kills off surrounding healthy cells.

Is it cheap? Sure. Does it always kill a plant? Of course not. Is there a better way to treat a fungal or bacterial infection that doesn't destroy healthy cells? Yep.

My personal view, I would never treat a phal for crown rot with peroxide. Having said that, my rationale for the couple of rescue phals I've been given that had crown rot was to put them straight to the trash. But I can certainly see where someone might attempt it. I just don't grow that way.

Here's an interesting article I just read about oxygen reactives as it relates to plants. Peroxisome Function, Biogenesis, and Dynamics in Plants | Plant Physiology Beware, it's a very boring read overall unless one's into that stuff, but it's basically saying the same about how plants cells react the same way human cells to H202.

I have used the Biosafe product for LECA treatment, but Physan @ 1 teaspoon/gallon or chlorine bleach @ 1 oz/gal works too.

50% peroxide is a great oxidizer. I was working in a manufacturing operation that made pigments for ceramic glazes, and we used organic flocculants to cause the powder slurry to clump up for dewatering before spray drying. If left in the powder, the viscosity of the glaze would increase with time, so we dewatered, stirred in some peroxide and it was completely degraded.

The AOS has had a few articles suggesting using H2O2 for disease control either either as a spray or drench and many of the speakers that have come to OS meetings mention using it during repotting. That’s why I was wondering if there was some science behind in or if was more of a “well that’s the way we’ve always done it” type of thing. I have no idea where the notion for actually submerging the orchid came from, I suppose the thought was if you can drench the pot you might as well throw the whole orchid in? :dunno: I usually see this brought up when people ask about killing fungus gnats, snails, “sterilizing” the root zone, or preventing any sort of pathogens from entering though cracked roots.
It’s not something I use in that manner, it just seems to be a pretty common recommendation. I rarely use it at work (operating room) so I don’t really use it at home. On plants OR people

This has been the main reason I have never really reached for it. If I need a fungicide for my orchids, I’ll use an actual fungicide. If it’s an area that is suspect, I’ll just cut it off and maybe dab a bit of cinnamon on the edge. If problems keep happening, then I’ve got some culture issues I need to work on. If I need to clean cutting tools, pots (plastic, not clay), or surfaces, I use a product for that like Physan 20. If I’m worried about cracked roots getting infected or nasty after a repot, I just keep the plant dry for a week or so. I still don’t see the point in trying to sanitize the root zone which is something I have seen discussed in other areas online. I’ve also seen it mentioned on other forums that people spray the roots down to kill things like fungus gnats, snails, and their eggs. Has anyone actually found this to work? I usually just repot in fresh media with a strong spray of water to the roots. I have yet to find a single treatment for those little bush snails that eradicates them. They remind me of cockroaches in that sense...

(Thanks for pulling this out, by the way! I figured o would get lost in that post after I wrote it)