Shelf life of physan-20

[cirillonb]

Some growers I know keep Physan-20 diluted in spray bottles throughout their greenhouses and use as needed. As a new in home grower I was wondering if it lasted very long so I e-mailed the company.
They told me that diluted, it is potent for 3 to 5 DAYS.
I guess I need to make it up as I go and in as small a quantity that I can reasonably measure.
I suspect the same is true of a number of concentrates.
"A word to the wise..."
Nick

[whygreenberg]

Hmm...

Is this really true? Anyone else here able to confidently corroborate that? Or is that just the company's line to keep people purchasing more?

[Ross]

Mine lasts much longer. I get like months out of a mix. I suspect they are telling what the "registered" strength and life is - not what folks really get. I wouldn't mind keeping mine for 2-3 weeks for sure.

[Des]

I was once told that physan degrades within a few days in strong light. So maybe if you kept your spray bottles in a dark place the diluted Physan will have a longer shelf life

[cirillonb]

Originally Posted by Ross

Mine lasts much longer. I get like months out of a mix. I suspect they are telling what the "registered" strength and life is - not what folks really get. I wouldn't mind keeping mine for 2-3 weeks for sure.

How do you know.
Nick

[cirillonb]

Originally Posted by whygreenberg

Hmm...

Is this really true? Anyone else here able to confidently corroborate that? Or is that just the company's line to keep people purchasing more?

It would be very difficult to scientifically prove or disprove the company's statement. If you feel that they are lying, then you shouldn't buy their product.
I am a retired physician and ran into the problem of outdated drugs all the time, In fact, when studied, most drugs lasted much longer than the stated (read: studied and proved) expiration date, but I would be reluctant to recommend someone use them for a serious condition. Orchids are precious and I don't want to use something on them that might not work or worse still, be dangerous if out-of-date.
Physan-20 is cheap enough to make up a batch every few days or when needed and discard the residual, from my point of view.
Nick

[whygreenberg]

Originally Posted by cirillonb

It would be very difficult to scientifically prove or disprove the company's statement. If you feel that they are lying, then you shouldn't buy their product.
I am a retired physician and ran into the problem of outdated drugs all the time, In fact, when studied, most drugs lasted much longer than the stated (read: studied and proved) expiration date, but I would be reluctant to recommend someone use them for a serious condition. Orchids are precious and I don't want to use something on them that might not work or worse still, be dangerous if out-of-date.
Physan-20 is cheap enough to make up a batch every few days or when needed and discard the residual, from my point of view.
Nick

I actually couldn't agree with you more about all that. I honestly didn't mean to say they were lying. Was just shocked by such a short length of time. I guess I can be a bit of a skeptic sometimes because there are companies out there that like to push product. Really, I was just looking to hear other members weigh in on if they'd heard the same thing, had reason to believe otherwise, etc. That's all.

[kavanaru]

my two cents...

now that you (cirillonb) mentioned expired drugs: the exp. date for drugs, is just the date when the drug has lost part of it effectivenes (in most cases, even less than 10%!). It does not mean that the drug will not have any effect if you take it like that, but since it has been tested and approved at a especific concentration it cannot be allowed to be sold/used after the expiration date (no scientific support it will be save!). In clinical trials, where pharmaceuticals know very well and have a close control of the investigational product, it is possible in most cases to relabel the drug, and extend the exp. date this way. However, and please keep this in mind and do not start using exp drug because of what I have posted here, for many drugs the level of "toxic" or non-desired compunds increases after the Exp. date, and therefore they can become poisonous or the side effets become to higher than normal!

so, it can be that the exp. date pf Physan, provided by the company refers to a similar situation.
My concern here is that if the product looses its effect after such a short period (extremelly short, for a product like that!) then an exp. date or a warning or especial storage instructions should be written in the label, which is not the case at all!

Please note I am not saying the company has lied, but it could be that depending on to whom you have spoken (could even be a call center in Bangladesh!) you have received only part of the information and not the whole picture! I would try again, and confront them with further questions à la "so, it means that after 3-5 days, the products is safe to be discarded in the environment or the fish pond?" - please note that according to the label the product is "Environmentally friendly", "Biodegradable" and "poses no human or environmental risk when it is used at recommended use levels" ...

weird label, isn't it?

[cirillonb]

I don't mean to create a controversy. My note was a "heads up". My e-mail to the company was triggered by the statement on their label under GENERAL CONTROL OF PLANT PATHOGENS ON INANIMATE HARD SURFACES the last sentence "Fresh solution should be prepared daily or when the solution becomes visibly dirty."
Nick

[Don Perusse]

I really beleive that allsolutions should be mixed as needed to give you the best results. That would include your fertilizer as well. Why waste what you don't need at the present time. For heavens sakes, it only takes a minute to mix a gallon or two of solution.
Just my opinion.......happy growing!