# Sterilizing bark/chc



## papheteer (Apr 11, 2011)

I have found some old (unused from 3-4 years ago) bark and chc in our storage room. Before using them, I kinda want to sterilize them somehow. Can I use the oven or microwave to do this? If so, how hot and how long? Thanks!


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## eOrchids (Apr 11, 2011)

I would put them in a boiling pot over a flame for five minutes or so.

The bark that floats are good and the ones that are no good, fall to the bottom.


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## Brian Monk (Apr 11, 2011)

Oven, 200 F for two hours.


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## Shiva (Apr 11, 2011)

Is there enough of the stuff to bother with in the first place?


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## papheteer (Apr 11, 2011)

Shiva said:


> Is there enough of the stuff to bother with in the first place?




There's about 2 cubic feet each of small bark and medium chc.


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## Shiva (Apr 11, 2011)

OK. That'a a sizable quantity. I'm with Brian Monk in this case.


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## NYEric (Apr 11, 2011)

high heat, as in a fire. then a spit of meat revolving over the flames! :evil:


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## Eric Muehlbauer (Apr 11, 2011)

Why not just add Physan to the soaking water?


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## Ray (Apr 12, 2011)

My thoughts exactly, Eric.


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## NYEric (Apr 12, 2011)

NYEric said:


> high heat, as in a fire. then a spit of meat revolving over the flames! :evil:



Then add cold drinks and voila!


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## papheteer (Apr 12, 2011)

thanks guys! I'll do the oven method!


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## Erythrone (Apr 13, 2011)

Eric Muehlbauer said:


> Why not just add Physan to the soaking water?




I don't think Physan is very effictive that way:

_Quaternary ammonium chloride salts (Green-Shield®, Physan 20® and Triathlon®). Q-salt products, commonly used by growers are quite stable and work well when used according to label instructions. Q-salts are labeled for fungal, bacterial and viral plant pathogens, and algae. They can be applied to floors, walls, benches, tools, pots and flats as disinfectants. Physan 20® is also labeled for use on seeds, cut flowers and plants. Carefully read and follow label instructions. Recommendations may vary according to the intended use of the product. For example, the Green-Shield® label recommends that objects to be sanitized should be soaked for 10 minutes, and walkways for an hour or more. Instructions recommend that surfaces be air-dried after treatment except for cutting tools. The label recommends soaking cutting tools for 10 minutes before use, then using the wet tool on plants. One way to do this is by having two cutting tools, one pair to use while the other is soaking. 

Q-salts are not protectants. They may eradicate certain pathogens, but will have little residual activity. Contact with any type of organic matter will inactivate them. Therefore, pre-clean objects to dislodge organic matter prior to application. Because it is difficult to tell when they become inactive, prepare fresh solutions frequently (twice a day if in constant use). The products tend to foam a bit when they are active. When foaming stops, it is a sign they are no longer effective. No rinsing with water is needed. _

http://www.umass.edu/umext/floriculture/fact_sheets/greenhouse_management/ghsanitz.html


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## NYEric (Apr 13, 2011)

What!? No bar-b-que!?


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## Ray (Apr 13, 2011)

I don't see why soaking would not be effective. As was stated, it is a contact disinfectant, and if absorbed by the bark/CHC chips, it seems to me that pathogens it comes in contact with will be taken care of.

As to heating, just how hot can you take bark before it starts to burn? I don't think that 200°F is going to necessarily kill all pathogens.


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## papheteer (Apr 19, 2011)

Ray said:


> I don't see why soaking would not be effective. As was stated, it is a contact disinfectant, and if absorbed by the bark/CHC chips, it seems to me that pathogens it comes in contact with will be taken care of.
> 
> As to heating, just how hot can you take bark before it starts to burn? I don't think that 200°F is going to necessarily kill all pathogens.



Ray, how much physan would u add to the water? Thanks!


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## papheteer (Apr 19, 2011)

NYEric said:


> What!? No bar-b-que!?



Eric, I would use the BBQ idea as a threat to plants that wouldn't bloom!


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## Ray (Apr 19, 2011)

I would throw the old bark away, but the label recommends up to 2 tablespoons per gallon for disinfecting inanimate objects.


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## fbrem (Apr 19, 2011)

why even sterilize it? are you potting up seedlings out of flask that are going into a sterile environment? can pathogens really build up on dry media in storage? Maybe I'm just lazy but I would just soak and use if I were repotting, no use sterilizing media that will just get reinoculated whenever you water. am I crazy here, I was just wondering if the extra sterilization step is worth the effort>


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## NYEric (Apr 19, 2011)

You may be right. The original post says _unused_ bark and CHC, At most I'd add a little physan into the presoak.


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## gonewild (Apr 19, 2011)

180 degrees for 30 minutes, does not matter the heat source.

That is 30 minutes from the time the center of the material reaches 180 degrees.


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## NYEric (Apr 19, 2011)

Can an oven do 180F? That seems kind of low.


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## gonewild (Apr 19, 2011)

NYEric said:


> Can an oven do 180F? That seems kind of low.



I don't know, I don't cook. :clap:

180 degrees for 30 minutes is what we used to do when we steam sterilized seedling flower beds. That temperature and time is all it takes to kill pathogens. I think USDA requires 140 degrees for 24 hours to heat sterlize shipments of lumber to kill pests.

If you use higher heat and longer times you may start to destroy organic matter which may result in the media not lasting as long.


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## Howzat (Apr 19, 2011)

Easiest way to disinfect, not knowing whether the pathogen is fungal or bacteria, I always use chlorine (14%) and add 50ml into 10litre of water. Soak for 1 day. You can use it immediately for large plant but for seedlings you can take it out of the soak and let dry for a couple of days. Otherwise put tap water and soak for another hour to get rid of excessive chlorine.


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## cnycharles (Apr 20, 2011)

chlorine would work, but fresh bark probably wouldn't have too many bad things. if it does, then it's likely old and you should incorporate it into your compost pile. chlorine and time will kill bad things, but i've had things react to tap water with low chlorine; heat is clean and nothing else needs to be done except maybe soak in water to rehydrate


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