Bactericide / Fungicide

[kmccormic]

Hi Guys!

I've lots of experience with the practicals of chemical bug controls, but I've never worked with bactericides or fungicides other than a quick root dunk in Physan when trimming roots during repotting. It's winter with temperatures dropping and problems may come up no matter how careful I try to be about watering frequency. I'm trying to determine the best ways and strengths to use them. Are they media drenches only, usually? Do you spray the foliage with them (and if there's a difference in usage, how could you tell?) If plants are mounted, can you dip the entire plant in them and leave for 10 minutes or so?

I've read some online, and trying to determine the indications of fungal or bacterial problems is intimidating to me. Learning experiences! Most of the online references state "apply a bactericide" without listing specific brands.

Is Physan20 really a bactericide and a fungicide? I'd read somewhere that it really isn't both, despite the bottle labels.

I have Physan20 and just added Thiomyl and Phyton 27, and I've never used them before. Are there any other products you might recommend adding to my product index? And recommendations about using the ones I've listed? Or other advice in general?

Thanks for your patience and help with these questions!

Regards,
Kara

[tucker85]

It all depends on what kinds of orchids you're growing and what problems you're trying to prevent. Generally I don't use chemicals unless I see a problem developing. I have a couple books on phalaenopsis culture, that do recommend drenching the media, once a month, with 1 teaspoon of Physan 20 per gallon. I've done that in the past but Physan seems to be a very mild bactericide/fungicide and I'm not sure how much good it does, but it doesn't seem to hurt anything. I also have some friends who use hydrogen peroxide as a drench. I haven't tried it myself.

Personally I feel that repotting phals and paphs annually is one of the best culture techniques for preventing disease problems. Other culture practices, like good air movement and not letting the leaves stay wet too long will help also.

You say that you have Thiomyl. You can use Thiomyl at 1 teaspoon to a gallon of water, once a month, if you want to do that. I prefer a contact (topical) fungicide, like Dithane M-45. I use it at 1 tablespoon per gallon of water, when ever I see any problems starting. It leaves a residue on the leaves but it seems to work well. I also recommend using a fertilizer that contains calcium. many fertilizers don't have it and it's important for building strong plant tissue that can resist fungus attack. I actually use a calcium/magnesium supplement that called Magical, added to my fertilizer water.

Sorry, I'm rambling on and on. Good luck with your plants.

[orchidsarefun]

Agree that improving cultural conditions are the best prevention, otherwise you are treating the symptoms and not the cause. However hydrogen peroxide is a good all round treatment to help you get there.

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[PaphLover]

When using 3% hydrogen peroxide as a drench and as a spray, should it always be diluted? By how much? And where does one get Physan20? I asked at nursery yesterday and the woman looked at me like I was speaking some other language.

I'm in Vancouver, BC, Canada.

[Orchid Whisperer]

The bactericides that may be available in Canada could go by different names in comparison to what is available in the United States (same goes for other countries). You may need to look up the active ingredients in Physan and see if they are available in a Canadian product.

[PaphLover]

Oh, ok. Thank you!

[orchidsarefun]

Originally Posted by PaphLover

When using 3% hydrogen peroxide as a drench and as a spray, should it always be diluted? By how much? And where does one get Physan20? I asked at nursery yesterday and the woman looked at me like I was speaking some other language.

I'm in Vancouver, BC, Canada.

I don't dilute the 3%, use it 'neat'

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[PaphLover]

Originally Posted by orchidsarefun

I don't dilute the 3%, use it 'neat'

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Ok. Good. I have too. Back to Costco I go!

[gngrhill]

I get my Physon 20 from Repotme.com

[silken]

Originally Posted by PaphLover

When using 3% hydrogen peroxide as a drench and as a spray, should it always be diluted? By how much? And where does one get Physan20? I asked at nursery yesterday and the woman looked at me like I was speaking some other language.

I'm in Vancouver, BC, Canada.

I'm not sure on the hydrogen peroxide. I know a friend used it on roots and they seemed to not like it. But then again the roots were in trouble or she wouldn't have used it so who knows why the roots went south after that.

As for the Physan 20, I believe it can no longer be purchased in Canada. I have done some checking and that seems to be the story I get. However, I have ordered it from the U.S. and had it shipped with no problems getting it thru customs. I order clear pots for our society and I get them from Quarter Acre Orchids. I have had Physan included with the order several times and it was stated on the packing slip, so I wasn't sneaking it in or anything. A friend ordered Phyton also and had no problem brining it in from the U.S. I have also ordered Cleary's 3336 (systemic fungicide) from the U.S. on its own and got it no problem.