Hey list,

I was curious, many have said that 3% hydrogen peroxide is a great way
to kill bacteria, fungi...etc, but if it can kill those things, why
doesn't it harm the plants? It's cells either way right?

Are plant roots more susceptible to H2O2 damage than leaves (if in fact
damage can occur)?

Cheers,
Xi

Xi Wang wrote:
Hey list,

I was curious, many have said that 3% hydrogen peroxide is a great
way
to kill bacteria, fungi...etc, but if it can kill those things, why
doesn't it harm the plants? It's cells either way right?

Are plant roots more susceptible to H2O2 damage than leaves (if in
fact
damage can occur)?

Cheers,
Xi

H2O2 (hydrogen peroxide) gets touted as a general greenhouse antiseptic
from time to time, usually in a much weaker dilution than 3%. This
claim seems dubious to me because H2O2 breaks down into water and
oxygen very rapidly, especially on contact with organic material. I
don't think very dilute solutions would be any more effective than
plain water.

Whether 3% H2O2 would harm roots and leaves, I don't know. I don't
have any plants I'm willing to sacrifice to find out.

Highly concentrated H2O2 is very nasty stuff: ask any chemist. I
mention this only because H2O2 enthusiasts often recommend folks buy
strong concentrations to formulate their own weak solutions.

J. Del Col

On Wed, 16 Mar 2005 08:07:10 -0800, "K Barrett"
wrote:

Well, we'll find out becasue I just dumped half a bottle over a Bulbophyllum
medusae that was smelling prety rank and had a slimy coating over the top of
the s.moss.
K Barrett

That kind of slime I hit with Physan. But I do water sick Phal's
especially if they have or have had crown rot with hydrogen
peroxide.

And Claude I thought you were very clear. Never had thought
about why it works. Just knew they used it on crown rot and had
a plant I wanted to save. At a $1 a bottle it was a cheap
therapy. And it worked on two of mine that had gotten down to 1
leaf and in one case it was a very limp leaf for a very long
time. Some Phal's are reluctant to keiki especially below the
crown.
SuE
http://orchids.legolas.org/gallery/albums.php

Xi Wang wrote:
Well, I was hoping to use it as an agent with which to control fungi.
I've heard that it works, but fungi need oxygen, so I'm not sure how it
can be effective.....


I don't officially know anything about it, but I do know that plants
have very tough cell walls. Fungi, as a rule, do not, as far as I know.
Hence, the hydrogen peroxide may be able to penetrate the fungal cells
more effectively.

The 'toxic' mechanism of H202 has very little to do with more oxygen.
At least in the way you think. It has everything to do with oxygen
radicals - charged derivatives of H2O2 that are very reactive with most
biological molecules. Including DNA. Oxygen radicals are one of the
most potent things that damage DNA. An excess of oxygen radicals will
modify proteins and DNA to the point where the cell can no longer
survive. Obviously a single celled organism is more prone than a
multicelled organism - it gets whacked from all sides, whereas a
multicelled organism has layers of cells, only the outer ones are affected.

I bet most of your 'slime' and pathogenic fungi are single celled fungi.

Rob


--
Rob's Rules: http://littlefrogfarm.com
1) There is always room for one more orchid
2) There is always room for two more orchids
2a) See rule 1
3) When one has insufficient credit to obtain more
orchids, obtain more credit