Question
QUESTION: My beloved Cymbidium is going downhill fast. It is always getting black spot/ brown leaves and I am able to avoid it by putting umbrellas over it when it rains. However, 2 weeks ago when I had to put my dog asleep, it rained and I did not put the umbrella over them. Literally within 24 hours the black spot was back. I may have waited a week, ( I was having a bad week), then purchased a topical fungicide "Serenade Garden" recommended by my local Armstrong. I cut off as much of the dead stuff as I could. However, it keeps getting worse, my beautiful flowers fell off and the leaves are 2/3 brown all the way to the roots.  The soil is not wet from what I can gather, and I moved it to a location under a balcony so it does get the right amount of sun and air yet is protected. I am at a lose of what to do. Do I keep cutting the brown leaves off? That would leave 1/3 of the plant leaves remaining, and/or do I treat it with a systemic? I'm very frustrated as my neighbor has 4 of them that are gigantic and do nothing but bloom constantly and never have disease. Since she is next door I cannot figure out what i am doing wrong.

Help please :(
Megan

ANSWER: Megan, I have seen this occur on many cymbidiums and other thin leaved orchids including some of my owm.  The earliest cymbidium hybrids, which were very large plants, produced lots of flowers and did not have this problem.  In the last few decades, the focus has been to create hybrids which were smaller in stature (called miniature cymbidiums).  This continuing hybridization appears to be a two-edged sword, bringing with it genes that make the plant less able to resist pathogens, particularly fungus. Once the damage occurs, it cannot be reversed.  However, use of a fungicidal spray containing cooper sulphate or other salt of copper seems to inhibit these lesions on new leaves. I spray this every week because new tissue on newly growing leaves is susceptible. Over time, the copper salt will leave a green deposit on the leaves which helps extend the protection. Also. try to keep the leaves dry and avoid high humidity.  Fungus, as you know, thrive in wet and humid environments.  Finally, orchid potting mix degrades into a soil-like mixture over time so a repotting in fresh fir-bark based orchid potting mix will help eliminate potting mixes that remain too wet in the root zone.

I mention this first because it is the only approach that I have found to combat this condition.  If this approach is ineffective, then it is likely that your plant has acquired a virus (most likely the cymbidium mosaic virus) which sometimes can produce similar symptoms.  I mention this last because there is no cure for plant viral infections and, in fact, they can be spread through the use cutting instruments or insects that have fed on the plant sap and move  to other plants-- thus spreading the virus.  Sterilize your cutting instruments before use as a preventative measure. Also, isolate you plant from others as another preventative measure.



---------- FOLLOW-UP ----------

QUESTION: Thank-you so much for your very detailed
reply. I am determined to keep it alive as it
has become a symbol of our furry one we
lost. To that end, would you mind
recommending a brand of spray to apply.
Last, is there a breeder that you recommend
I buy from for future Cymbidiums that maybe
have not been through the hybridization
process. This is the 4th plant to succumb to
the same disease.
Many thanks.

Man

Answer
I use Kocide manufactured by DuPont.  If you can't find it at your garden center you can find a source by googling "Kocide".  A good source of superior cymbidiums is the Santa Barbara Orchid Estate.  If you google "The Orchid Mall" and click on plant sources, you can find it listed under the "S" group of suppliers.