# how long can a chemical stay useful



## jone0391 (Aug 11, 2002)

The nursery I work at will mix some general purpose fungicides or other chemicals in their back pack sprayer and use the same chemcial mixture for a week at a time. Is that safe to not mix the chemical each time you need to use it? Thanks, Marie


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## Reed (Aug 14, 2002)

Geez.

I hope you wash so frequently that you scrub some skin off.

Nothing in the Federal Register regarding safety of specific compounds delves into the area of mixing pesticides (I say pesticides in general terms). Complicated research goes into toxicity studies that for the most part extropolate animal data into human tolerances. Most of what industry is concerned about however, is quantifying effectiveness for the designed purpose, the health effects come later and only when it has to.

Many chemical families do NOT mix, have shorter half-lives than others, synergistic effects occur when mixing reproductive inhibitors with outright toxins or growth regulators. I can go out to my garage and create a bomb with the simple mixing of two nutritional compounds and adding a third common element to detonate at a designed time, using only a mixer or a glass insert barrier to trigger the outcome. I can't believe a nurseryman would do what you're saying but I do believe they could - business is business I guess. What he thinks is that he's used it this way so far with tolerable plant mortalities so I guess he'll remain doing this. 

I would add though, that label restrictions prohibit using these chemicals (in this case anti-fungals or fungistats) in this manner and he's directly violating Federal Use Standards and laws. Perhaps the local enforcement authorities don't give a rat's ass about this practice but I know of many Feds that would love to know more. It's your life, and I know employment is a necessary evil, but there may be some dire chronic effects over a period or years ahead so you may at least want to document the practice with dates, methods, verbal directives from him, and labels from the chemical themselves. Save this stuff for future reference, trust me on this. I was diagnosed terminal with lymphoma in '93 and we paper trailed the exposures with known science and it pointed to the smoking gun held by the US Forest Service, who knowingly falsified data regarding warnings and use laws.


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## Reed (Aug 14, 2002)

Opps Marie, I forgot the question.....

No, mixed (petro-based or water based) compounds shouldn't be contained for more time than it's mixed and used for, 24 hrs max.


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## City climber (Aug 18, 2002)

*chemical storage*

You should never mix more than you plan to use in a single spray.storing chemicals, after they have been mixed poses several hazards and should always be avoided.


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## John Paul Sanborn (Aug 18, 2002)

It does depend on the product and the temp stored at. 

Degradation of product will effect the efficacy of the treatment, just settling out will reduce the actual rate of applcation.

From a cost benefit point of veiw it would be best to mix what is needed. If a little is left over it could be kept in the sprayer and treated as a rinsate in the fill.


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## Jumper (Aug 18, 2002)

*Chemicals*

Since you obviously have a connection to the net, do a search for the manufacturer and ask them questions directly. I did so recently for Killex and RoundUp, and quickly got answers back from their people in the know-both questions involved shelf lives of the products. I also had a bottle of SEVIN with no instructions and got a copy of that document on line as well.


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## jimweed (Aug 18, 2002)

ive been spraying pesticides for 16 years commercially, and at the end of the day i always have mixed product left in my tank for tommorrow. add water, chemical and away i go again the next day . those are oil based products no problem. but i wouldn't leave it more than a week. wetable powders though will settle to the bottom of your tank in a few hours if un agitated and get gummy. as for mixing pesticides together, most fungicides are compatible with a majority of insecticides, but not many herbicides are compatible with each other, check with your supplier. definately killex and round up are not effective if mixed together.


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