Sterilizing pruners - Orchid Board

Becca · #1 09-19-2008, 12:53 AM

I just recently started using Physan 20 for sterilizing my pruners....before I was using a lighter to heat up the edge of the blade, wasn't sure if that was really doing the trick so I switched to the Physan.....I have a couple of questions.....is it safe to re-use the solution after I trim lets say some rotted roots or a spike that has finished blooming? If so how long is it good for? Also if I am using Physan 20 as a soak (the directions recommend 1 Tablespoon per gallon for I think 10 minutes) is it safe to re-use this solution for soaking another plant or is it best to change the solution in between? I had a dendrobium that had some fungal problems in the potting medium so I soaked it. Is one soak enough if I change the potting medium? The roots and rhizome were effected as well. It was not pretty!

Ray · #2 09-19-2008, 07:01 AM

Physan can be reused as a dip disinfectant for tools - I recommend at least a 10-minute soak and when today's work is done, dump it, mixing a new batch for next time. If, in the course of using it, I see it's getting dirty, I dump and remix too.

Physan is a good surfactant, but is a topical disinfectant only. If you soak your plants, any pathogens on the surface will be killed, and it's pretty good at getting into crevices, but if there is an internal infection, it's not likely to do much.

As far as reuse is concerned, it depends - like that for tools, I base that decision on the appearance of the solution.

Becca · #3 09-19-2008, 12:20 PM

Hi Ray! What would you recommend for an internal infection, although I don't "think" I have one.

I had suspected for a while (about 3 months or so) that I had a fungal problem since I kept seeing white fungal dots in the potting medium, but the plant looks pretty healthy and has a nice sized new growth. I was pouring the physan solution through the pot off and on, but I kept seeing it come back. The potting medium was a mixture for Dendorbiums I bought (medium coconut husk chips, small coconut husk chips, lava rock, sponge rock, pea gravel, charcoal, and granite chips), but I think in my orchidarium it was retaining moisture for to long.....I also had some old rotted roots (which I trimmed off yesterday), but with the new growth, I still have a lot of healthy roots. After soaking the dendrobium yesterday and letting things dry out, I can still see some of the fungus growing. Sorry I am probably not using the correct terminology. Should I retreat with a drenc/soakh again right away or should I wait and if so how long? I am scared to pot it up again and have the fungus spread into the medium again. Thanks for your help!

Ray · #4 09-20-2008, 09:27 AM

I seriously doubt that you have an internal infection - they usually are black rots that are almost impossible to eradicate.

I also have to wonder about your ID of a continuing fungal problem, as a 10-minute soak in a tablespoon of Physan per gallon will absolutely wipe out any such pathogen.

Sounds to me like you need to adjust things in the Orchidarium. How is the air movement?

Becca · #5 09-20-2008, 10:12 AM

Well the orchidarium came with two fans located at the top....they move the air around pretty well....but then I had to mess with things since I was having problems maintaining humidity when I purchased it (was around 50% and I wanted around 70% to 80% for the mounted orchids) so I purchased a MistKing system and added an additional fan. The mist gets on the ceiling of the orchidarium and the water drips down, I think what may have been happening was that the water was dripping into the potting medium....I have most of the plants positioned so that they don't get the drips on them and cause problems. I only have one other plant that I have seen this fungal looking stuff on it but I thought it went away with the physan treatment....I will have to unpot it and see what is really going on deeper in the medium.

When you say a 10-minute soak in a tablespoon of Physan per gallon will absolutely wipe out any such pathogen, would I still see the fungus attached and it be dead and I just need to scrub it off? I have a white fungus that grows slowly on my mounted orchids that are on a particular type of wood as well....Physan barely keeps it at bay, and it is only on the wood mounts, not the cork, and that is in both orchidariums (I have an Exo-Terra I converted).