run for hills and don't look back!

I grew tomatoes in my greenhouse last winter as an indicator plant for
ethylene. Tomato plants are highly sensitive to ethylene and exhibit a
characteristic wilting (epinasty) which make them valuable as an indicator
plant for this problem. The leaf petiole of an epinastic tomato leaf is bent
downward, like it is wilted, however it is completely turgid to the touch
and the root system is healthy.

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. Phal flowers themselves
give off this gas in small amounts all during their blooming. I seem to be
under the impression that it is the rapid increase of ethylene in the flower
tissue after pollination that triggers the wilting and subsequent capsule
development in a recently pollinated Phal flower. I don't remember where I
picked up this factoid.

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.

From the NC University Agriculture Department comes this article that points
out Cattleya are rather sensitive too.
"Ethylene: Sources, Symptoms, and Prevention for Greenhouse Crops"
http://www.ces.ncsu.edu/floriculture/hils/HIL530.pdf

"Cattleya don't like it either
0.04 to 0.1 ppm for 8 hrs "dry sepal"
0.002 to 0.02 ppm for 24 hrs Dying and bleaching of the sepals"

Phals were not mentioned in the table of plants and responses found in this
paper, but IIRC they are similar to the Cattleya numbers: bud blast at 0.002
ppm. IMHO, a very easy number to reach in a greenhouse sealed up tight to
save on winter heating costs.

Al
PS Whitefly generate spontaneously from Tomato plant tissue. The presence
of ethylene increases whitefly production. I can't find the study....but I
know I read it someplace.


"Steve" wrote in message
...
John DeGood wrote:

Susan Erickson wrote:

The problem is more apt to be that you have fruit close to the
plant. The ethylene gas that ripens fruit also ripens buds.


I've always kept apples, bananas, melons, peaches, pears, etc. far away
from my plants, but in recent weeks I've suddenly experienced serious bud
blasting on many of my orchids. I've never had this happen before.

Last month before the first frost I picked all the remaining tomatoes in
my garden and set them to ripen on a kitchen counter that happens to be
right next my orchid shelves. Until a few moments ago I always thought
of tomatoes as vegetables: after all, one grows them in a vegetable
garden. Susan's post just made me realize my terrible blunder: tomatoes
aren't vegetables -- they are fruit that produce ethylene to ripen.

I'm posting this so others hopefully won't repeat my stupid mistake.

John (I can't believe I did that!) DeGood

Well, you've finally settled that "vegetable or fruit" debate once and for
all! (not that I ever had any doubts)

You know... I have often brought in dozens of ripening tomatoes in the
fall (not this year) and they were stored a few feet away from some of my
orchids. I never gave it a thought before now either. Did I experience bud
blast? Not really. Maybe on some Dendrobiums, but that was on 2 unhealthy
plants that didn't have the energy to bloom anyway. Do tomatoes produce
even close to as much ethylene as apples? I doubt it. Do they produce
enough to blast orchid buds? I have no idea but I wouldn't be surprised!

Steve