Sanitizer - why not Cl or alcohol over Physan?
 

Hi - As a beginner I have been reading about good sanitation practices, esp for repotting techniques. I find most posts here recommend using a quat ammonia type product to not only sanitize tools & surfaces but also to soak plant or potting media. I'm wondering why alcohol or bleach soln is not adequate for sterilizing tools. I was hoping something like cinnamon would be fine for a preventive. Is it because some fungi and viruses are resistant to basic sanitizers? And I'm concerned about using very much Physan 20 in my home environment. Thanks for your guidance and all the input you share. Madlyn

Bleach can be harmful if used in too concentrated a solution.
Cinnamon is good to put on fungal infections and any areas where you have cut the orchid, but is not the best for dusting the media/roots because it dessicates them.

Because I do not have access to Physan yet, I have been using a bleach solution- weak to spray/soak plants, strong for my tools.

I've used hydrogen peroxide on bacterial infections with success.

I can't say if Physan is better or not.

After looking a bit closer, Physan has more than just one ingredient, I believe there is more to it than just being a disinfectant, as it is advertised and used as an Algaecide, Virucide, Bactericide, and Fungicide.

Hi Madlyn,

Welcome to the OB. I don't use anything to treat a healthy plant. An once of prevention is worth a pound of cure. ;)

Just do a pre-soak in plain water (or fert), and let newly potted plants dry a bit more for a while. Flame sterilize your tools - you can treat for bacteria or fungus, but once you transmit a virus it's too late.

I think you've gotten some good advice already.

But I'd like to add that many orchids are sensitive to chlorine or chlorine products.

This is why tap water is not highly recommended amongst most orchid growers.

I'll give you a few examples of orchid groups that don't tolerate chlorine at all. There's a serious risk of injuring the plants to some degree or another or killing them outright.

1. Pleurothallidae
2. Zygopetalinae
3. Disanae
4. Cypripedium

Alcohol must be used with caution as well.

I generally don't recommend using isopropyl alcohol on the roots. Leaves and stems are okay.

70% is the maximum. Any higher and you'd have to dilute it with water.

Ethanol (aka ethyl alcohol) is fine as well. Again I caution against using it for the roots.

Hydrogen peroxide (H2O2) has been used as a mild disinfectant on plants as well. H2O2 when used to disinfect orchid seeds is actually pretty powerful, and should be timed.

I use Hypocalciumchlorate as a disinfectant for tools, work area, pots, and once in a while my hands if Ive been working with questionable plants and then go to work with a stud plant. I use it in an almost super solution, its pretty stable.

The alcohol isnt going to do much besides make a virus or disease inactive for a short time.

Madlyn,

Don't be concerned about using Physan in your home. it is commonly used as a disinfectant in hospitals, and is very close to the chemicals used to keep swimming pools and hot tubs clean.

Your toilet bowl cleaners and drain de-cloggers are far more hazardous, but you should still treat the chemical (ALL chemicals) appropriately.