Xref: kermit uk.rec.gardening:172747


"martin" wrote in message
...
On Sun, 26 Oct 2003 22:43:47 +0000 (UTC), "Franz Heymann"
wrote:


"Jim W" wrote in message
news:1g3g6gz.vesamxyagc56N%00senetnospamtodayta@m acunlimited.net...
Franz Heymann wrote:

Mist propagation was mentioned in another thread quite recently.
That
triggered me into asking something I have always wanted to know:

What does mist propagation do which cannot be done by inverting a
transparent container over the cutting?
I have always thought that the purpose of either action is simply to
maintain an atmosphere which is as nearly as possible fully saturated
with
water vapour in order to minimise evaporation from the surfaces of
the
leaves.


It's automated, air circulation is better , thus you have a more
bouyant
atmostphere (which in turn 'should' reduce fungal risk to some degree).

What does "bouyant atmosphere" mean?
Why should it reduce the risk of fungi? If the fungus spores are there,
they will be there, whether the atmosphere is bouyant or not, whatever
bouyant might mean.

buoyant?

Actually, yes. I did not notice!

Franz

"Franz Heymann" wrote in message
...

"Mike Hunter" wrote in message
...

[snip]

I've read that by slightly over-misting, the water runoff from the
leaves
removes fungal spores.

This sounds like wishful thinking.
Surely, if there are spores around in the air, the mist is as likely to
trap
spores in the air and deposit them on the leaf.


Over-misting is achieved either by a timer which runs after the
"electronic
leaf" has indicated saturation or by moving the sensor to the extreme of
the
mist distance so that it is saturated last. The timer method is
preferred
as
being more consistent.

Since the aim is to have near-continuous 100% humidity a "buoyant
atmosphere" seems unlikely. The action of the misting nozzles will,
however,
stir up the air a bit.

I still don't have a clue as to what might be meant by a "bouyant
atmosphere"

The water to the mister nozzle(s) will normally be considerably cooler
than
the air temperature and so will cool the plants whilst the mister is
actually operating. Covered/closed systems controlled only by an
electronic
leaf may experience severe temperature cycling.


Idealy the mist unit will allow the cuttings to just reach the point of
dryness before misting again and will then slightly overmist so there is
some run off, dispite your sceptisism Franz it does almost eliminate fungal
problems! Why the coolness? well its water under pressure suddenly released
through the misters the temperature plummets and of course water on the
leaves means cutting the water loss from the cuttings. You can however get
very good results from a small polytunnel made of white polythene if you are
prepared to use a bit of fungicide.

--
Charlie, gardening in Cornwall.
http://www.roselandhouse.co.uk
Holders of National Plant Collection of Clematis viticella (cvs)

On Mon, 27 Oct 2003 08:55:13 +0000 (UTC), "Franz Heymann"
wrote:

What does "bouyant atmosphere" mean?
Why should it reduce the risk of fungi? If the fungus spores are there,
they will be there, whether the atmosphere is bouyant or not, whatever
bouyant might mean.

buoyant?

Actually, yes. I did not notice!

just checking :-)
--
Martin

David Hill wrote:

".........Wish I could afford 'experiments' like that;......."

Well my fogger cost £9.95 from Maplin (special offer)
uses around 3/4 pint of water an hour on continuous running, but with a
timer I am going to try 15 mins on 15 mins off, You get more fog from warm
water so if it is in contact with the soil warming cable should work better.
Will probably require a very low volume fan but should find something low
cost, only need around 3inch.
The larger fogging machines such as they use in disco's seem not to run on
water.....pity as for under £40 you can get a machine with quite an output
(Maplin do one for £44.00 that has an output of 2,500 cubic feet per
minute).
With that you could do a whole glasshouse minute.
did see 2 at a trade show One £800+ and the other around £1400.
The control unit for Mist is getting on for £200 so this could be a much
more cost effective system and not put out so much water, so that things
like Dahlias that don't like being wet could benefit.


How long does the fog stand with the cheaper units though? AFAIK you
need to spend quite a bit of cash to produce a fog that will stand for
several hours.
/
J

Franz Heymann wrote:

"Jim W" wrote in message
news:1g3g6gz.vesamxyagc56N%00senetnospamtodayta@ma cunlimited.net...
Franz Heymann wrote:

Mist propagation was mentioned in another thread quite recently. That
triggered me into asking something I have always wanted to know:

What does mist propagation do which cannot be done by inverting a
transparent container over the cutting?
I have always thought that the purpose of either action is simply to
maintain an atmosphere which is as nearly as possible fully saturated
with
water vapour in order to minimise evaporation from the surfaces of the
leaves.


It's automated, air circulation is better , thus you have a more bouyant
atmostphere (which in turn 'should' reduce fungal risk to some degree).

What does "bouyant atmosphere" mean?
Why should it reduce the risk of fungi? If the fungus spores are there,
they will be there, whether the atmosphere is bouyant or not, whatever
bouyant might mean.

As far as I'm concerned its a term used to describe the atmosphere of a
well maintained glasshouse or other propagation/protected area. Eg an
adequate combination of fresh air, humidity, etc.

At least thats how its always been described to me.

As in"
"Wülfinghoff Alstroemeria B.V.
http://www.wulfinghoff.nl/alstroemeria_info.html
Monday, October 27, 2003

Ventilation temperature should be 16° - 18° C. As the spring crop
develops and light levels improve the minimum temperature can be allowed
to rise. It is important to give sufficient ventilation to control
humidity and maintain a *buoyant atmosphere*. Rapid fluctuations in
humidity can cause plant stress and severe leaf tip scorch on some
varieties. During the late spring and summer period the crop should be
kept cool. Ideally the soil temperature should not rise above 20° C.
Shading at this stage is beneficial."

An example of use of the term taken from the web.

Reduction fungal spores will only 'thrive' in conditions that are right
for them.
If you have an overwet, saturated atmosphere, with temps too high or too
low for rooting, you may get plenty of fungus but a very low success
rate.! Effectivly a 'good' crop of fungus

Thus you can 'reduce' the loss to fungus by a combo of things.
Fungicides and the right level of humidity (not too saturated but enough
for good levels of rooting) & ventilation.

/
Jim

The message
from "David Hill" contains these
words:

/snip/

The larger fogging machines such as they use in disco's seem not to run on
water.....pity as for under £40 you can get a machine with quite an output
(Maplin do one for £44.00 that has an output of 2,500 cubic feet per
minute).

Disco thingies use dry ice. (solid carbon dioxide.) They just condense
any water already present in the air as a rule.

--
Rusty Hinge
horrid·squeak&zetnet·co·uk
http://www.users.zetnet.co.uk/hi-fi/tqt.htm

"Franz Heymann" wrote
What does "bouyant atmosphere" mean?
Why should it reduce the risk of fungi? If the fungus spores are there,
they will be there, whether the atmosphere is bouyant or not, whatever
bouyant might mean.

I should've answered your earlier point about 100% humidity. In mist propagation humidity is not 100% or anywhere
close to that. The system is set up to just keep a thin film of moisture on the leaves - this can be adjusted to
'wean' the cuttings. There is in fact quite a bit of evaporation & therefore cooling but transpiration is limited
by the permanent presence of moisture on the leaves so the cuttings remain turgid. You are rooting the cuttings in
full sun -full speed photosynthesis and keeping the foliage cool enough to avoid stress while the bases are at an
optimal temperature for stimulating root formation. The buoyant atmosphere Jim is referring to is a greenhouse
grower's term for the air not being dry or laden with moisture and with some air movement. The still damp
conditions that favour germination of fungal spores are not present even though the spores are always there as you
know. Buoyancy is much easier to demonstrate than to explain. I take somebody into a hot dry greenhouse, open the
vents, damp down the paths and benches - watch the temperature go down and now you can feel what a buoyant
atmosphere is. Likewise it's cold and damp - get some heat on and a little ventilation, suddenly it's more
comfortable - the air is buoyant.

Rod

"........Disco thingies use dry ice. (solid carbon dioxide.) They just
condense any water already present in the air as a rule........."

Whilst a few do there is a very large range of foggers that work from a
reservoir tank using a fogging liquid.
http://www.discountdisco.com/acatalo...Foggers_8.html

This is the intro to an American web site for foggers

The concept of fog and its benefits have been in use for over fifty years.
While most commonly known for cooling, fog can be used for a variety of
applications. These applications include humidification and propagation for
greenhouses, frost protection, fire and smoke control, odor control, special
effects, etc... These applications can be utilized for residential,
commercial, and industrial purposes including restaurants, hotels and
resorts, poultry and dairy farms, animal kennels, brick and concrete
manufacturing plants, metal forging, plastic extruding, outdoor patios,
playgrounds, stadiums, outdoor malls, outdoor "smoking" areas, theatrical
stages, amusement parks, landscaping and water features, greenhouses,
arboretums, produce display and storage facilities, golf courses, tennis
courts, etc...


The concept is inherent in nature such as water vapor, clouds, and fog that
manifest due to the earth's environment. DWM Productions fog machines and
systems can create the same environment where and when you want it. Using
normal tap water and pressurizing it to 800 PSI with our high pressure pumps
we force water through our patented brass and stainless steel nozzles. This
atomizes the water to droplets as small as four microns, a fraction of the
diameter of a human hair. We have created a fog that can be utilized almost
anywhere. The process is very energy and water efficient.





--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

"Charlie Pridham" wrote in message
...

"Franz Heymann" wrote in message
...

"Mike Hunter" wrote in message
...

[snip]

I've read that by slightly over-misting, the water runoff from the
leaves
removes fungal spores.

This sounds like wishful thinking.
Surely, if there are spores around in the air, the mist is as likely to
trap
spores in the air and deposit them on the leaf.


Over-misting is achieved either by a timer which runs after the
"electronic
leaf" has indicated saturation or by moving the sensor to the extreme
of
the
mist distance so that it is saturated last. The timer method is
preferred
as
being more consistent.

Since the aim is to have near-continuous 100% humidity a "buoyant
atmosphere" seems unlikely. The action of the misting nozzles will,
however,
stir up the air a bit.

I still don't have a clue as to what might be meant by a "bouyant
atmosphere"

The water to the mister nozzle(s) will normally be considerably cooler
than
the air temperature and so will cool the plants whilst the mister is
actually operating. Covered/closed systems controlled only by an
electronic
leaf may experience severe temperature cycling.


Idealy the mist unit will allow the cuttings to just reach the point of
dryness before misting again and will then slightly overmist so there is
some run off, dispite your sceptisism Franz it does almost eliminate
fungal
problems! Why the coolness? well its water under pressure suddenly
released
through the misters the temperature plummets and of course water on the
leaves means cutting the water loss from the cuttings. You can however get
very good results from a small polytunnel made of white polythene if you
are
prepared to use a bit of fungicide.

Aslways, a good understanding and a nice explanation.

Franz

Jaques d'Altrades wrote:

The message
from "David Hill" contains these
words:

/snip/

The larger fogging machines such as they use in disco's seem not to run on
water.....pity as for under £40 you can get a machine with quite an output
(Maplin do one for £44.00 that has an output of 2,500 cubic feet per
minute).

Disco thingies use dry ice. (solid carbon dioxide.) They just condense
any water already present in the air as a rule.

The more professional ones use dry ice. The cheaper ones use a chemical
mix.
/
Jim

"Rod" wrote in message
...

"Franz Heymann" wrote
What does "bouyant atmosphere" mean?
Why should it reduce the risk of fungi? If the fungus spores are there,
they will be there, whether the atmosphere is bouyant or not, whatever
bouyant might mean.

I should've answered your earlier point about 100% humidity. In mist
propagation humidity is not 100% or anywhere
close to that. The system is set up to just keep a thin film of moisture
on the leaves - this can be adjusted to
'wean' the cuttings. There is in fact quite a bit of evaporation &
therefore cooling but transpiration is limited
by the permanent presence of moisture on the leaves so the cuttings remain
turgid. You are rooting the cuttings in
full sun -full speed photosynthesis and keeping the foliage cool enough to
avoid stress while the bases are at an
optimal temperature for stimulating root formation. The buoyant atmosphere
Jim is referring to is a greenhouse
grower's term for the air not being dry or laden with moisture and with
some air movement. The still damp
conditions that favour germination of fungal spores are not present even
though the spores are always there as you
know. Buoyancy is much easier to demonstrate than to explain. I take
somebody into a hot dry greenhouse, open the
vents, damp down the paths and benches - watch the temperature go down and
now you can feel what a buoyant
atmosphere is. Likewise it's cold and damp - get some heat on and a little
ventilation, suddenly it's more
comfortable - the air is buoyant.

Thanks for the explanation. I have learnt.

Franz

Rod wrote:

"Franz Heymann" wrote What does "bouyant atmosphere" mean? Why should
it reduce the risk of fungi? If the fungus spores are there, they will
be there, whether the atmosphere is bouyant or not, whatever bouyant
might mean. I should've answered your earlier point about 100% humidity.
In mist propagation humidity is not 100% or anywhere close to that. The
system is set up to just keep a thin film of moisture on the leaves - this
can be adjusted to 'wean' the cuttings. There is in fact quite a bit of
evaporation & therefore cooling but transpiration is limited by the
permanent presence of moisture on the leaves so the cuttings remain
turgid. You are rooting the cuttings in full sun -full speed
photosynthesis and keeping the foliage cool enough to avoid stress while
the bases are at an optimal temperature for stimulating root formation.
The buoyant atmosphere Jim is referring to is a greenhouse grower's term
for the air not being dry or laden with moisture and with some air
movement. The still damp conditions that favour germination of fungal
spores are not present even though the spores are always there as you
know. Buoyancy is much easier to demonstrate than to explain. I take
somebody into a hot dry greenhouse, open the vents, damp down the paths
and benches - watch the temperature go down and now you can feel what a
buoyant atmosphere is. Likewise it's cold and damp - get some heat on and
a little ventilation, suddenly it's more comfortable - the air is buoyant.

An extremly good way of describing it Rob.. You are quite right, it is
one of those terms that is easier to demonstrate than explain.

Cheers
//
Jim

In article
1g3g6gz.vesamxyagc56N%00senetnospamtodayta@macunl imited.net, Jim W
writes
A mist bench may be covered or uncovered. heated or unheated, though
ususally the former..

Its worth noting that misting, in Horticultural terms, is not quite the
same as fogging.

True fogging equipment, such as is used to fog large glass-houses is
quite expensive and very different from a low scale sand and mist bench
rooting bench, which can be anything from a DIY 'heath robinson' affair
to some very high tech systems.


Does this then need a plumbed in water supply or does a header tank work
to supply the water?

--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk

Janet Tweedy wrote:

In article
1g3g6gz.vesamxyagc56N%00senetnospamtodayta@macunl imited.net, Jim W
writes
A mist bench may be covered or uncovered. heated or unheated, though
ususally the former..

Its worth noting that misting, in Horticultural terms, is not quite the
same as fogging.

True fogging equipment, such as is used to fog large glass-houses is
quite expensive and very different from a low scale sand and mist bench
rooting bench, which can be anything from a DIY 'heath robinson' affair
to some very high tech systems.


Does this then need a plumbed in water supply or does a header tank work
to supply the water?

You'd need water and pressure, same as any other system..

So either a pump and supply of clean water or mains I guess.
/
Jim