Physan 20

[Masdyman]

Originally Posted by Ray

1. Physan is a topical disinfectant, Jen. If you have a systemic bacterial rot, the thing to do is to cut off all infected tissue and seal the wound on the plant with cinnamon.

2. Adding Physan to your RO tank is inconsistent. You may have the right dose at first, but when you use some and it refills, it gets more-and-more dilute. Because of that, I am trying adding it to my fertilizer concentrate tank, instead.

Hi Ray ,my RO tank is not that clever ,my unit just fills my feed tank which i have to then turn the RO unit off when full . It has a overflow just in case i forget , so how beneficial would it be to add it too the stored RO instead of a monthly treatment or do you do both ?
Would a constant supply of Physan in the water not harm the plants long term ?

[Ray]

To be truthful, I have no idea of the benefit one way or the other, nor the effects of long-term, constant exposure. A couple of thoughts, though:

My continual treatment is a LOT less concentrated that my former, periodic, direct drenchings, and I never saw a problem with that, so I doubt it's an issue.

My point about the application to the storage tank is this: Start with a full tank at correct Physan rate (whatever you may decide that is). Use half the tank and refill it, and now the whole tank is only at a 50% concentration. Use half of that, refill, and it' at 25%. Sure you can add the appropriate amount to "correct" the concentration, and it would be easy with the example I have given, but what about irregular usage volumes, and do you really want to mess with that?

[Lars Kurth]

Following the example of another grower, I have started to add a small amount to my RO tank. He claims that his incidence of botrytis and other fungal infections has plummeted since doing that,

Here in UK it's not approved therefore unobtainable but I managed to buy it on ebay. Naughty I know...

Another option to disinfect rainwater and keep RO water tanks clean is to use H2O2 or UV light.

As for H2O2, you would use a 100ppm solution (i.e. 1 litre of 3% H2O2 will desinfect 300 litres. The water can be used to water plants after 1 hour. The water will stay saturated with O2 & H2O2 molecules for a few days, which means it remains sterile. To test the effectiveness of the present H2O2 you can use sticks e.g. Quantofix Peroxide 100. I

This should kill all fungus spores and bacteria, but it does not kill moss or algae. Note that pathogens dont adapt to a prolonged application of H2O2, unlike other fungicides.

I tend to use H2O2 to treat water when it is stored for a while to ensure that the water is not contaminated. I have not noticed any detrimental effect on the plants.

Using UV light over your water tank has the same effect.

It may be that Physan is more effective: it definitely prevents build up of algae. On the other hand it can kill moss, which looks nice on mounted plants and does not seem to be detrimental.

[jenmonkey]

Thanks Ray, both for keeping me in S/H pots with my constant orders, and for explaining that. I'm still a little green about the chemicals, so that cleared everything up. Topical vs. systemic. Got it!

Not to completely derail the topic, but what about Cleary 3336? Also topical?

[Masdyman]

Something else to think about i guess, i do have some H202 as well . What i am interested in is cutting down fungal infections & rots etc over winter ,will H202 have a impact at keeping these down .

[Ray]

Lars,

The idea of adding the disinfectant to the tank is not to disinfect the tank of water, but to spread a disinfectant around the greenhouse to keep other pathogens at bay.

Hydrogen peroxide, because of its rapid, spontaneous decomposition rate, will only be good right away after adding it to the tank.

[Lars Kurth]

The idea of adding the disinfectant to the tank is not to disinfect the tank of water, but to spread a disinfectant around the greenhouse to keep other pathogens at bay.

I started using H2O2 because the rainwater in my tank got infected with a pathogen a couple of years ago and I lost nearly 1/3 of my collection in a period of a few weeks.

Of course Physan would have helped had it been available in Europe then.

[Lars Kurth]

I just managed to buy some Physan 20 on eBay as well.

Here is another question: has anybody used Physan with a hydrofogger? I have found that if I add fertilizer to the water that feeds the hydrofogger it clogs up quite quickly (deposits in various places).

[Ray]

Jen, Cleary's 3336WP is a systemic fungicide.

Lars - I don't know if I'd run Physan through a hydrofogger. It's a pretty good surfactant, so if the concentration is "right" (or wrong), it could become a "hydrofoamer".

[Lars Kurth]

Well: I thought I'd give it a try. The reserour in the fogger holds about 1 gallon of water and I added a teaspoon (2.5 ml) as per recommended concentration. It didn't turn into a foamer (-: Of course there is the issue of breathing in Physan fog, so you don't really want to put the stuff in a water butt but only into the foggers reservoir.

If it clogs up, it just has to be cleaned. So far does not look it.