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Old 02-13-2016, 01:20 AM
Ed Ed is offline
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Default Re: Harvesting wild mosses and plants. Bringing in unwanted pests.

There are multiple things that are occurring that directly impact the ability of the bleach to sanitize the plant materials.

First off we have the problem of dilution due to reaction with the plant materials, soil or other organic materials in the solution.

Second most people ignore the fact that hypoclorite ions are unstable over time which means that the bleach solutions used to make the dips reduce their effectiveness over time as the loss of hypochlorite further dilutes the bleach. So bleach that has been sitting for awhile is requires a different dilution ratio to be in the correct zones.

Quote:
Originally Posted by BrainBug View Post
What I don't understand about the Science Daily article was this; "We found that because of the topology of the spinach leaf, nearly 15 percent of the surface may 'see' a bleach concentration that is 1,000-times less than that of the rinse solution," I don't understand how the topology of a leaf could effect concentration strength on certain areas of the leave unless saying that the concentration is 1,000 times less is another way of saying it's not contacting at all.
I can think of at least two things that can contribute to it. Keep in mind that the shape of the leaf exterior can easily have topographic features that combined with the wax cuticle can prevent the hypochlorite molecule from getting close to the surface of the leaf (also ignoring the reaction of the bleach with the organics of the leaf which then further reduces the concentration of bleach at the surface of the leaf).

I would expect that leaves with even greater textures would result in even greater levels of protection.

Heavier waxy coating such as those found on bromeliads and some other plants are going to be even more problematic as cracks or irregularities in the waxy cuticle will further shield pathogens from contact.

Quote:
Originally Posted by BrainBug View Post
This seems more like an issue of either spraying down leaves with a bleach solution on leaves that are already wet with water thus immediately diluting the solution on spots that hit water droplets or an issue
The tests were done on submerged leaves and not sprayed materials using a specially designed flow chamber. The original news article is here UCR Today: How Clean is Your Spinach?

Quote:
Originally Posted by BrainBug View Post
Ed, in light of what you posted about the potential ineffectiveness of bleach solution soaks is there a more effective reasonable alternative you could suggest?
I actually cannot think of a single disinfectant that does not suffer from the same drawbacks. If you add a surfactant to the bleach solutions then your going to have to use a sufactant that doesn't react with hypochlorites and works at that pH.

If you go back into the original discussions the bleach suggestion was developed out of what was done with prepping plant tissues for cloning. It was brought up because people were routinely getting cuttings from one person's enclosures and going home and installing them into their own enclosures which is an issue with respect to pathogens.

At this time people place excessive emphasis on bleaching the plants which due to a number of factors such as the lack of ability to contact the surface of the plant (along with other issues) pretty much can be said to be marginal at best and totally ineffective at the worst resulting in false confidence.

Some comments

Ed
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