Quote:
Originally Posted by Bodil88
Roberta very gently told me that HP is real bad for orchid roots
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I think she said something a little bit different. She said H202 /can/ be harmful to the roots, and that it is probably ineffective against living snails.
H202 naturally forms in rain water in small concentrations, and there is research that very low doses can be beneficial to plants. On the other hand it is hyper reactive as oxygen doesn't want to bond like this, and will react with other molecules, particularly organic ones to steal hydrogen, sometimes explosively: rocket backpacks use high concentration H202 to react with gold to produce thrust sufficient to achieve escape velocity.
When H202 reacts with other molecules it rips them apart, (potentially rendering benign chemicals toxic), but generally destroying organic molecules. At low concentrations this is an effective treatment against viruses and other simple organisms, but is not really a problem for more complex organisms, but at stronger concentrations will do serious harm to anything organic. Eg, if you spill 3% h202 on your hand its not going to do much harm. If you spill 20% h2o2 on your hand you will, what would happent your hand at 100% concentration is beyond me, but likely not at all good..
So when she said H2O2 can harm your roots she was right. If the strength is too high it can and will totally kill your plants. At very low dosages (like under 1%) it might kills some pathogens, but whether its a win is not clear.
I also have seen the recommendations to use light H202 treatments during a first repot and for a while i tried it, but I really don't think it is necessary for a hobby grower at home growing plants obtained from reputable sources. I can understand a commercial grower using treatments like this on scale, but for a hobby grower I don't think it makes a difference and I dont do it myself anymore at all.
Personally if Roberta says it is ineffective against snails I would trust her. She said you should try doing a long soak and then follow up with a treatment for snails or slugs and a repotting. I would follow that advice. And maybe just for peace of mind, afterwards give the plant a course of insect spray treatment just to set your mind at rest. From what I could tell from that thread you weren't clear on whether it was some kind of black critter crawling around or if it was snails.
FWIW, I overreacted to a false-spider-mite infection on my baby orchid collection, and then followed some recommendations for using H2O2 on my plants that I think had a typo and said I should treat with %5 H202, that I think should have said %0.5 (eg 1/10th the strength), and in the end I am quite sure the H202 was the reason they all died. So the concentration of H2O2 is super important, and getting it wrong can and will kill the plant.
So just to put that into perspective most H202 sold at the drugstore for cleaning jewelry, or in the past cleaning cuts, is typically 3%. That is around 6 times stronger than your plants probably can take.
So Id say stay away from H2O2 unless someone like Roberta tells you to use it. Id trust her over a youtuber any day.