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MarilyninOttawa
If you remember I had asked for some questions a couple of weeks
back and am now prepared to provide some answers.
Almost any question you want answered was
my request and four questions were presented.
1 - John asked "Marilyn, do you know how to measure the
light in a GH using a digital camera? Or even a film camera ?"
To respond to this question, I first searched
the internet for possible sources then asked someone knowledgeable
about digital cameras for some pointers. Secondly, I posed some
questions to myself.
A) What is the relevance of relative light
level to hobbyist orchid culture? While high light levels are
recommended for orchids such as Cymbidium and low light levels
are said to be tolerated by orchids such as Phalaenopsis, we
must be careful not to consider light out of context with temperature,
humidity, air movement, light source and plant growth state.
B) What is the relevance of metering to meaningful
light measurement? Plants use light for photosynthesis. They
must be able to produce more photosynthetic product than they
use in respiration in order to grow and ultimately flower but
too much light especially when air movement is limited can be
counterproductive. Irrespective of what a meter reads and what
requirements are listed for a particular orchid, a good grower
always looks to the plants for the final say as to whether the
light level is or is not appropriate for their purposes.
C) What are the most important points to bear
in mind when choosing a camera as a tool to measure light? Camera
type is irrelevant except that one must be able to set the ISO
or digital equivalent film speed manually or in a menu; and one
must be able to read the aperture/f-stop and shutter speed/exposure
setting.
So, in answer to John's question:
- Step 1 - During the brightest time of the
day, place a white sheet of paper where you wish to measure the
light level.
- Step 2 - 35 mm camera - Set film speed to
ISO 100; digital camera - Set digital equivalent to ISO 100
- Step 3 - Point the camera at the paper being
sure not to shade the paper with the camera or your body. The
paper image should fill the viewfinder.
- Step 4 - Read the f-stop/aperture and shutter
speed/exposure setting.
- Step 5 - Refer to a published table such
as is found at Linda's Orchid Page http://www.orchidlady.com/camera.html
Read down the f-stop column and across the exposure setting row
to arrive at the approximate light intensity in foot candles.
Note that Foot-candles × 10 = Lux. A typical low light
recommendation is 1000 foot candles for Phalaenopsis and about
2000-3000 for Cattleya.
- Step 6 - Measure at various locations throughout
the growing area at different times of the growing season. Apply
shading, install supplemental lighting or move plants according
to your observations. Watch the plants carefully for signs of
leaf stress (reddening or yellowing indicating too much light
for that plant under those conditions) or of etoliation (weak
growths indicating too little light for that plant under those
growing conditions).
Is that answer what you were looking for,
John? Please remember that Camera type is irrelevant except that
one must be able to set the ISO or digital equivalent film speed
manually or in a menu; and one must be able to read the aperture/f-stop
and shutter speed/exposure setting
Ed_in_Sat
Note of interest: most digitals will not set below ISO 200 because
it is a function of the receptor sensitivity. I don't mean to
make an issue, but below ISO 200 on a digital, be sure you are
getting an actual reading, not an interpolated one.
John_in_Arcadia,_CA
Mine will. Thank you Marilyn. That is exactly what I wanted.
I have copied it all down and will try it soon. I am sure it
will work fine.
MarilyninOttawa
Thank you Ed. Not all digitals are alike. You likely need an
advanced model with this function.
janetteh
The older the camera, the more luck you will have. Most of the
newer ones are all automatic. The one that James uses for award
pictures is about 30 years old but is totally manual and he can
set it the way he wants/needs it.
MarilyninOttawa
Good point Janette. By the way, I use a very low tech measure
of light level. I use a piece of white paper and my hand held
between the light source and about one foot above the paper.
I add shade cloth until the shadow just disappears. This gives
me perfect lighting for Cattleyas, Catasetum, Vanda. Lower light
or filtered light reaches the lower shelves and this is where
I place the Phals and pleurothallids.
MarilyninOttawa
2 - Steve asked "I only have one burning question about
orchids. That would be the cause of that disease that has been
killing off my Phals. You saw the web site I made on that."
After the question was posed, it was suggested
that Ed Wright might be dealing with this topic in detail at
a future time. Meanwhile, suffice it to say that an unknown contagious
microorganism seems to be involved in many of these instances.
It is possible that there is more than one organism and that
we are dealing with several parallel disease processes. I recommend
that a grower first check to see if the cause is mites. These
can be seen under the microscope. If there are no mites involved,
then a decision must be made as to whether to dispose of an infected
collection and start anew or to try and eliminate the causative
agent(s) from the plants. There has been some success with various
fungicidal preparations but if the source is not controlled,
the problem could strike again. Sanitation in the growing area
is very important. Do you have anything to add at this time,
Ed?
Ed_in_Sat
I suggested privately to Steve that he might be dealing with
a form of Psuedomonas. I also refenced some work I had participated
in on gram negative bacterial pathogens in plants.
MarilyninOttawa
That is interesting. I have isolated pseudomonads from Cypripedium
roots. These are motile bacteria that would move in water films
and through splash but would be vulnerable to simple dryness
if one could vacate a growing area and let it dry out. They would
likewise be vulnerable to bleach solution when outside the plant
but of course, if they are inside the plant, that presents a
problem.
Ed_in_Sat
We found some relatively empirical evidence that they might cross
over to create flu-like symptoms in mammals. That aspect was
not funded or needed, so it was not explored, just noted.
MarilyninOttawa
3 - Tom in Kentucky asked: "How many taxonomists does it
take to name an orchid species?"
Good question! Plant taxonomy was once and
in some cases still is the domain of both professionals and amateurs
working with collected material in the field and in herbaria.
Herbaria are collections of pressed, dried specimens which may
or may not have been well documented or even well preserved at
the time of collection. Early workers lacked the instant communication
possible today. Working in different places around the globe,
one or sometimes two individuals might have been working with
the same species without knowing of the other's work. Some published
their suggested names without due diligence. This resulted in
confusion and ultimately in guidelines where precedence of publication
was the way names were accepted or not.
Secondly, the botanical community has to accept
the nomenclature: even today there is dispute over which name
is most appropriate to describe a species old or new. So, in
answer to this question, it can take just one person to name
an orchid or it can take many, one coming up with a better argument
as to why a plant should have a particular name. Nowadays, molecular
evidence is lending support to some old specific and generic
epithets. These names still must be accepted within the botanical
community which continues to be a source of much debate.
Does that answer your question about taxonomists?
pecteilis_in_KY(Tom)
If I wanted to grow a Laelia I think the safest thing to do would
be to plant the label!
MarilyninOttawa
4 - Al asked: "How do you prepare your flower/plant for
judging? Can they be staked? Just what is accepted and what's
not?"
Staking can be used to effectively train and
display blooms to their advantage but at the show, must never
be intrusive or compete with the beauty of the blooms. You will
probably want to stake during transport but these stakes may
not be the ones used for display purposes. Poorly staked specimens
can be unsightly. No stakes can mean that lovely spray of Phalaenopsis
droops unattractively with the flowers all facing down.
Effective staking must begin while the spike
is developing. Spikes are often brittle and can break if not
dealt with early. Once buds are about to appear, be certain to
keep the plant in the same position relative to the light source
as this will keep the flowers properly aligned.
Choose unobtrusive stakes. These can be fine
green-coated wire for Masdevallia to bamboo for Oncidium. Firmly
but discretely attach the spike to the support. I use floral
tape (green or brown). Be sure that the material will not damage
the spike.
If your plant could be a winner then consider
the impact of stakes in the award picture. The award photographer
may have difficulty photographing your prize bloom if stakes
clutter the backgound. Remember that it the exhibitor's responsibility
to remove stakes, not the photographer.
Ed_in_Sat
Let me suggest that if staking is required for the type, do it
early. Most staking problems I have seen resulted from staking
a formed inflorescence for display purposes. That's too late.
John_in_Arcadia,_CA
Many at our hows are using those small plastic clip type things
to fasten the spikes to a stake.
MarilyninOttawa
Some plastic clips look ugly because they are prominent and not
hidden by foliage.
John_in_Arcadia,_CA
Most that I have seen are really quite small and the color of
the stake. You can hardly see them
MarilyninOttawa
The ones I have seen locally have butterflies attached and are
a bit much. If clips are unobtrusive then there should be no
problem. I agree that floral tape can hide aborted buds. I have
used a twist of florist wire (green) although you must take care
that the wire does not dig in. As Ed said, train early and at
that stage, emphasis should be on ultimate spike quality, not
on appearance. Heavier support used during transport can be removed/replaced
when you get to the show.
John_in_Arcadia,_CA
I have the type without the butterfly. They are much less obtrusive.
jeanne23_from_oz
Floral tape has been banned here in Oz because there were a number
of growers hiding aborted buds and this cause a bit of an uproar
at the time. Clips can be unobtrusive if placed properly.
Ed_in_Sat
If one has access to it, 'grape tape' comes in generous rolls
and is much cheaper than floral tape, which it resembles. There
are two grades - most orchid growers are happier with the lighter
grade.
janetteh
[re:award photography] James will not remove stakes. He always
has the owner, if available, to remove the stakes. Sometimes
they have refused even though he explains that it will detract
from the bloom. It is amazing at how they (stakes) will stand
out in a picture.
MarilyninOttawa
Its their decision but I agree, the picture can never be a good
as it could have been without that prominent stake.
MarilyninOttawa
Paul asked: "With bark getting sort of hard to find, is
anyone using cypress mulch as a growing medium? Or what are you
using?" Does anyone have a comment?
pecteilis_in_KY(Tom)
Osmunda if you live in Flas. Or coconut chips. last as long as
bark, cheap, plentiful and easy to use.
MarilyninOttawa
Paul, I have no experience with cypress mulch but I do have with
coconut husk chips which are working well with a wide range of
orchids. You might want to try cypress mulch with some spare
plants to see what happens.
Ed_in_Sat
Take precautions against snails in today's osmunda!!!
pecteilis_in_KY(Tom)
And red bugs. But still....
janetteh
We have several people here who have tried cypress and have had
success with it. The secret is to amend it with charcoal or sponge
rock to open up the media. Don't pack the cypress fiber too tightly
in the pot.
jeanne23_from_oz
It seems that peat & perlite is the favourite mix for a lot
of growers in Qld and I must say that there seems to be great
success for those who are using it. I am a bark grower myself
pecteilis_in_KY
Can you "straighten" a phal sepal even though you know
it will flip back at night?
MarilyninOttawa
Phal blooms mature over several days. What is reflexed may eventually
straighten. You are not permitted to manipulate flowers for judging
purposes. Perhaps Ed has something to add?
Ed_in_Sat
You have given the correct answer, Marilyn. I do feel, however,
that the greater Vandaceous group may permit a bit of dressing.
Many of these flowers rotate as they open, from a little to 180
degrees. I find nothing objectionable in setting flower elements
into a natural plane. I HAVE seen Vanda flowers so 'realigned',
however, that veins were square edged. That may be overkill.
jeanne23_from_oz
Sometimes a tissue can add enough weight to the sepal to keep
it forward after placing it in the correct position.
MarilyninOttawa
I have noticed that phal blooms can disorient during transport.
Careful packing with soft tissue between blooms can help control
this. Be certain that the material used to support the petals
does not abrade them.
MarilyninOttawa
Thank you Ed for the useful comments this evening and to everyone
who joined in including the question-providers. The questions
were thought-provoking. |