Robert Huber <[EMAIL PROTECTED]> queried thusly:
> I read that one way of disinfecting tools used to trim
> dead roots from orchids is to use a bleach solution. What
> is not clear is the bleach used as is from the bottle or
> should it be diluted? Also how long does it have to stay in
> the bleach; just dipped in or allowed to soak for some
> period of time? Is there a better chemical to use>
Several people have e-mailed me privately along these lines, so I'll just answer here.
I would recommend the following in terms of the efficacy of tool use and re-use:
Best: New tool each time. Single-edged razor blades run $7 per hundred locally
(hardware store paint department), or about 7 cents each. Use once, dipose of in
coffee can labeled "SHARPS" when full. For more control over the blade, use a blade
holder such as a hemostat or clamping forceps. Single-use scalpels can be had for
cheap on "eBay." I use the No. 22 for heavy stuff, No. 15 for smaller stuff.
Also good: Thermal sterilization of blades. Since other pathogens are of concern
(including fusarium), autoclaving (same as pressure cooker) for 15 minutes at 15 psig
is fine. This is obviously not practical for most people. Bead boxes are commonly
employed for use in labs that do virus elimination in tissue culture; a minute or two
at 250 C is adequate between cuts. Boiling for 10 minutes exceeds the TIP of plant
viruses with a ten minute exposure, but lacks practicality. Others use a torch
(propane, etc.); this has its own set of hazards. One article in the AOS Bulletin
years ago suggested a can nailed to the bench served as a good holder for a live
torch; wire stands are available for cheap as well. Such high heat ruins the temper of
good tools.
Satisfactory: Chemical disinfection with scrubbing. Tools should be immersed in 10%
bleach (1:10 of the "old" 5.25% sodium hypochlorite, or 1:11 of the "new" Ultra Clorox
at 6% sodium hypochlorite), strong calcium hypochlorite ("Pool Shock"), or
strong/saturated TSP solution for 10 minutes or more. When shopping for pool shock,
make sure the label says calcium hypochlorite; locally, it's all the new
trichloro-s-triazine-trione (a.k.a.,dichloroisocyanuric acid, trichloroisocyanuric
acid), which is a poweful oxidizing agent to be sure, but does not have the very high
pH of solutions that have traditionally proven effective in plant pathogen control.
TSP is also problematic, as it has left the market in certain areas for concerns about
eutrophication of waterways; the front label may say TSP, but the actual contents may
not be.
If shear-type cutter (pruners) are to be cleaned, the blade should be opened and
closed to facilitate exposure of the edge to disinfectant. Scrubbing with an old tooth
brush to remove infectious tissue (plant sap) to optimize exposure is suggested.
Dunk-type immersion for a minute or two is probably used by more people than anything
else, and is probably adequate for most purposes.
Cheers,
-AJHicks
Chandler, AZ
_______________________________________________
the OrchidGuide Digest (OGD)
[EMAIL PROTECTED]
http://lists.orchidguide.com/mailman/listinfo/orchids
