Add to that, those "99.9% efficient" non-vented propane or NG
heaters/fireplaces/gas logs. They are virtual death to orchids. I was once
told that orchids were taken into mines as an early warning indicator of
gasses that might be noxious to humans. What I thought was cold injury was
actually ethylene damage. I ripped out the non-vented heater and installed
an exterior-vented heater. So far, so good. No bud blast this Fall/Winter.

Jeff
"Al" wrote in message
...
http://www.safnow.org/publications/f...nts/FF_612.pdf

This is an article called Ethylene: A Stealth Destroyer, by Cindy
Hoogasian. I am interested in comments from the peanut gallery. :-)

I thought it was very interesting. Talks about Ethylene scrubbers and
removing it from the environment, and provides links to resources and
products to help reduce it in your growing environment. Phalaenopsis are
known to be very sensitive to this gas and bud blast is often the result
as well as premature flower drop, where flowers open that should last for
several months but wilt only after several weeks. The article talks about
the gas in floral production in general and does not mention orchids. In
a greenhouse, not only is this gas produced by the plants themselves and
the combustion process of our heaters, it is produced during the breakdown
of potting media and as a byproduct of molds and bacteria and plant debris
like leaves and flowers that drop under benches. It is also produced in
the ground under the greenhouse as part of the life-cycle processes of
organisms living in the ground. Even with a properly vented heater, it is
possible in a well sealed greenhouse to see high levels of Ethylene.

Here are the first few paragraphs.

ETHYLENE IS TO PLANT LIFE WHAT
carbon monoxide is to human life: A colorless,
odorless, tasteless gas that kills. Although everyone
is susceptible to CO2, only some cut flowers
are sensitive to ethylene - it kills discriminately,
but injures relentlessly.
Controlling ethylene is critical in the floral industry. Some
studies show that ethylene is to blame for 30 percent of the
industry's crop losses. Unchecked ethylene adversely affects
how cut flowers perform in consumers' homes and diminishes
their value. It doesn't take much ethylene to do damage -
concentrations as low as 0.5 to 1 parts per million can diminish
cut-flower longevity.
There are two ethylene sources: Systemic ethylene, which is
produced by the flower itself, and environmental ethylene,
which is produced by fruit, gasoline engines, cigarette smoke,
scraped stems, leafy debris in coolers, bacteria-laden buckets of
solution/water and Botrytis-infected floral material.