QUESTION - Using Physan 20 in ALL greenhouse water ? - Orchid Board

EdinAZ · #1 03-31-2009, 02:51 PM

I'm not sure if this is the correct forum for this, but if an admin feels it should be moved, go ahead and do so.

I have a large RO system with pressure tank for all of my greenhouse watering (misting is straight "house water"), and it feeds through an irrigation controller, so I have several "zones" with different watering cycles. I do any other watering manually, and have a "plain water" hose, and one that runs through a Dosatron for fertilizing (both also RO water).

My question is:

I have a spare Dosatron injector. Could I set this up so that ALL water going into my automatic system is injected with Physan 20 (BEYOND the RO, obviously)? I've used Physan 20 for years and it has worked well as a bactericide/fungicide.

I just wonder if applying the Physan automatically every time I water, would be a good prophylactic measure to keep algae, fungus, etc. at bay.

I'll be re-configuring my irrigation zones, which will involve re-plumbing the valve set-up, so it would be easy to do at the same time. Any problems with combining it with the fertilizer watering?

Any experience, ideas, opinions, comments, etc. are welcome. (ANY comments . . . call me an idiot if you want to . . . just explain WHY I'm an idiot, and that will be helpful).

Thanks in advance.

Ed

DebsC · #2 03-31-2009, 06:15 PM

I don't know how much help I'll be since I'm probably and idiot, too. But I would think using the Physan 20 all the time might be a little much?

I use it in my fogger drip pan every month or so or whenever I remember it, which isn't often.

How much would you use and at what strength do you think it would be when it got to the plants? I know that too much will damage the leaves.

I think this is a good question and an interesting subject you've brought up. Hopefully, someone who knows a bit more than I do will pipe up here.

camille1585 · #3 03-31-2009, 06:43 PM

Just my

, I don't think using anything constantly as a prophylactic measure is a good idea. By using a chemical all the time ( insecticide, fungicide, I'm assuming it's the same with physan) you run the risk of seeing resistances develop, and then you are really stuck when you have a problem. Not too mention that it's not to good for the environment to always have chemicals going in the soil with the runoff.

Ross · #4 04-03-2009, 12:13 PM

I agree with the above. Even as a preventative, you wouldn't want daily use. There have been threads in the past where preventative use has been discussed (preventing algae growth.)

orchideric · #5 04-04-2009, 08:36 PM

Dear Ed,

Do NOT use Physan with every watering. It is not a fungicide but has a secondary effect of lessening fungi. The reason is that Physan chemically strips the cuticle layer from the leaves. Freshly germinated fungal spores literally get washed away with the top layer of cuticle.

Some Phalaenopsis growers overused Physan. They grew very pretty plants but with leaves having a seriously thinned cuticle layer. So, when the plants were sold they invariably died within a few weeks because the were overwhelmed by pathogens once they were no longer swimming in Physan. Think boy in the bubble.

The goal in a growing range is to have a healthy flora of fungi and bacteria and only spray chemicals when something gets out of control. This is the same reason that we pasteurize growing media, not sterilize it. We want to eliminate pathogenic organisms but not all oragnisms.

Hope that helps, Eric

cabbo · #6 04-04-2009, 11:44 PM

Quote:

Originally Posted by orchideric

Dear Ed,

Do NOT use Physan with every watering. It is not a fungicide but has a secondary effect of lessening fungi. The reason is that Physan chemically strips the cuticle layer from the leaves. Freshly germinated fungal spores literally get washed away with the top layer of cuticle.

Some Phalaenopsis growers overused Physan. They grew very pretty plants but with leaves having a seriously thinned cuticle layer. So, when the plants were sold they invariably died within a few weeks because the were overwhelmed by pathogens once they were no longer swimming in Physan. Think boy in the bubble.

The goal in a growing range is to have a healthy flora of fungi and bacteria and only spray chemicals when something gets out of control. This is the same reason that we pasteurize growing media, not sterilize it. We want to eliminate pathogenic organisms but not all oragnisms.

Hope that helps, Eric

How (why) do we pasteurize growing media? I dont understand. I just take it out of the bag, soak it and use it. Am I missing something?

orchideric · #7 04-04-2009, 11:52 PM

Chris,

I meant for general plants. When you buy potting soil or a soilless mix, it has been steam pasteurized.

With bark and other epiphyte mixes there is no need to pasteurize because they are unlikely to have any soil-borne pathogens.

Sorry for the misdirect, Eric

EdinAZ · #8 04-05-2009, 03:09 PM

Thanks everyone who responded to this question . . . you all DID explain EXACTLY why I'm an idiot.

I'm going to forget this idea, and stick with ocassional hand-sprayer applications only on what I observe as problem areas.

And thanks to OB for helping keep me out of trouble by having access to this forum.

Ed