Hort soap mixed a few years ago still good?

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Green
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Hort soap mixed a few years ago still good?

Post by Green » July 25th, 2021, 1:59 am

I mixed up horticultural soap a few years ago from concentrate. Is it likely still good? Or could it have bad bacteria in it? Not sure if it denatures their cell wall or not...Morph??

Also, is it likely to help with the cause of sooty mold on Hollies? Or at least help to remove the black? I've seen soap recommened for that.

Thanks.

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MorpheusPA
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Re: Hort soap mixed a few years ago still good?

Post by MorpheusPA » July 25th, 2021, 3:51 pm

Check it. It may still good, but look--if it's growing black stuff or brown stuff, discard it. If it smells awful, discard it. Shelf life of horticultural soap is usually 3 to 5 years, so "a few" sounds marginal. Concentrated soaps don't go bad due to the salt content. Diluted ones, however, are bacteria food eventually--I have a diluted concentration of Dawn that proves that even surfactants will eventually decay.

If it's bad, no big deal. Use 1 Tbsp any liquid or dish soap and 1 tsp baking soda in 1 gallon water and spray the plant. That's really wide-spectrum, so don't overspray too much, but it'll knock out most molds. Hollies are not going to react terribly negatively to this, but I'd advise doing it in the evening, allowing it to sit for about 30 minutes, then rinsing it off. Some plant whitening or yellowing might result due to stripping of waxes off the plant, but it should be extremely minor if it's visible at all.

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Re: Hort soap mixed a few years ago still good?

Post by Green » July 25th, 2021, 4:53 pm

Checking my old posts, it's likely that it was mixed 4 years ago. There is white buildup or precipitate in the bottom of the gallon container. It's not bulging...in fact, it's puckered in. it's Safer brand Insect Killing Soap. I have the bottle of concentrate, also, purchased that year. It, too, is puckered in at the sides.

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Re: Hort soap mixed a few years ago still good?

Post by MorpheusPA » July 25th, 2021, 6:20 pm

It's sucked up the oxygen in the container (and probably some of the nitrogen, too) to decay off the soap, hence the depressurization of the bottle. When you broke the seal initially, some bacteria got in. Or were there in the initial process; it's not done to pharmaceutical standards.

(Joke) If you're not part of the solution, you're part of the...precipitate. :-) (/joke)

At this point, if you don't feel comfortable with it, discard it and mix new from the concentrate (which is also clocking down in terms of time, but I'm more comfortable with). If you want to play with it, read on.

If you can shake it and get the precipitate to dissolve back in, no problem. Sometimes solutions set close to saturated will do that when they get cold, and are just a bit hesitant to dissolve back in when warmed, particularly fatty acid based ones. No huge damage. If it won't dissolve back in, then I'd give up and make new from the concentrate.

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Re: Hort soap mixed a few years ago still good?

Post by Green » July 25th, 2021, 10:53 pm

Interesting. I would've thought the implosion was temperature related.

Good joke. I'll dump the mix. What's the most environmental disposal method in your opinion?

That was the mix that precipitated out. The concentrate is in a dark colored container. I can't see what's going on. I don't feel like transferring to another container is a great idea (contamination). Just shake it up, pour some out, and see how it looks?


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Re: Hort soap mixed a few years ago still good?

Post by MorpheusPA » July 26th, 2021, 11:32 am

For a soap? Check the bottle for recommendations, but most likely they're either going to tell you nothing or simply to follow local laws, which pretty much means to simply dump it down the drain and follow up with hot water. Standard sewage processing can handle it. Rinse the container with very hot water, clean it out, sterilize it with 165 degree to boiling water if the plastic can take it, and you're good to go for next time.

Sure, dump some of the concentrate into a disposable paper cup or something, make sure it's OK (it almost certainly is), and then use it. They probably keep it in the dark container to avoid photo-degradation, which is pretty smart of them. I keep my soap stored in a dark closet with good air circulation (it's my walk-in with an air vent).

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