What you are describing sounds a lot to me like a Taiwanese disease
called Taiwan Yellows. The Taiwanese have been using high levels of
antibiotics for years on these plants in their giant production houses
to control Psedomonas bacteria. They have used these antibiotics so much
that they have created a super strain of the bacteria which although
latent when they ship their plants to foreign countries usually erupts
on infected plants in a month or two after shipping. Often the cool
temperatures in countered in shipping in containers by sea and the
cooler environs of finishing greenhouses in say North America and Europe
often portend the onset of the bacterial infection. We have had many
customers come in with these mass produced plants from Some of the Big
Box stores wanting us to diagnose the problem. We simply don't allow
those plants in our retail area anymore due to the virulent nature of
this bacteria.
My own personal experience goes back to the world orchid conference in
Miami in January of 2008. I went there to look for plants to add to my
breeding stock and had purchased 10 Phal. bellina coerulea from a
Taiwanese vendor. I brought them back to Minnesota, potted them up and
put them on the bench to grow and flower out in the coming summer. After
about 2 or 3 weeks I lost one of the plants and then another etc. every
week or two until I started noticing that in the same area radiating in
an outward circle more and more of my plants were becoming infected.
This went on until early summer and the circle of death was enlarging as
time went on. I had thrown out over $50.000 worth of plants and not just
Phalaenopsis but any other species as well. I tried using every
fungicide and bactericide I could find including Physan 20, Phyton 27,
Cleary's and others and could not stop the spread. I had to get the
University of Minnesota involved and they looked at the cell tissue and
found that there was the highest concentration of the bacteria in a cell
that they had ever seen. Their suggestion was to destroy every plant in
the greenhouse and then to bleach all the greenhouse surfaces including
walls, benches, floors glazing everything!
After collecting orchids for 30 years I could not imagine destroying
plants that could simply not be replaced. I just happened to read in a
greenhouse trade magazine about a new product that was made of dimethyl
ammonium chloride laced with urea that would go inside the plant tissues
and kill bacteria, fungal and even virus from within but yet still
preserve the nucleus of the cell. I was ready to try anything so I
called the company that made it and they sent me some samples to try.
After 1 application the disease was halted. I applied the product 2 more
times at 2 weeks apart and managed to clean the bacteria right out of
the plant.Yellow leaves, slowly over a period of 2 or 3 months regained
their green look and what amazed me more was the cleaning of certain
orchid viruses right out of Stud phalaenopsis that I knew had viurs but
kept anyway for historical purposes.
One of the symptoms can be a yellow watery filled leaf. The disease
spreads through water and can swim across benches and up walls as well
as across the floor. I know of folks in Canada and the US who have lost
their whole collection to this disease some were commercial growers and
others were hobbyists.
Not all Taiwanese plants or growers have this problem but I do believe
that Since some countries like the USA or other European countries
started allowing Taiwanese Phalaenopsis to be imported with the Sphagnum
moss and pots they were originally growing in the problem has only
gotten worse. Bare root plants didnt seem to be as much as a problem
before. I have also personally seen Dendrobium weevils hiding in the
sphagnum moss and then climb up the flower stems to chew on the flowers.
Us growers were asked by the U.S.D.A. for comments and opinions about
allowing plants from Taiwan in to the US with the potting mix (moss)
still on the roots and in pot. US growers all voiced their opposition to
this idea but we were brushed aside as what this was really about was a
reciprocal trade deal made during the Clinton era. The Hawaiian growers
tried to sue the government but they made a mistake and sued them in
Washington D.C. where things have a habit of being tilted in the
goverment's favor. It would have been better to sue in Hawaii. The
Hawaiians then decided to impose a ban on Plants arriving in Hawaii in
Moss and in pot but the USDA forced their hand and told them they
couldn't impose a State rule over a Federal rule regarding national
agricultural commerce.
I would suggest that any serious hobbyist or commercial grower either
isolate new plants for a time of treat them and isolate them to prevent
a tragic loss of beloved stock that is sometimes irreplaceable.
--
Best wis
*Orchids Limited
4630 Fernbrook Ln N
Plymouth, MN 55446 USA
TOLL FREE 1-800-669-6006
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