Question
QUESTION: Wayne,
I have a couple of Cymbidiums whose leaves seem to be turning yellowish and discoloring. Some of the leaves are light green which I know is the right shade of green, I have also made sure it gets its fair share of air via natural breeze and also a couple of fans.

I have treated all my orchids with fungicide and insectide as of late.

I have my orchids, including the cymbidiums in my garage; I live in Orlando. I water them once per week and feed them 20-20-20 year round.

Perhaps it is not an issue given that it is winter time. I have taken several pictures so you can take a look for yourself, you can see them at the following links; BTW, I took them at high resolution so you can get a good look at the issue (they may take a bit of time to load).

http://71.42.14.237/caripito/images/orchids/Cymbidium1.JPG
http://71.42.14.237/caripito/images/orchids/Cymbidium2.JPG
http://71.42.14.237/caripito/images/orchids/Cymbidium3.JPG

As you will see, I have a couple of pots. On the second picture, you will see that I trimmed the leaves down to the bulb because they died off.

Please let me know your thoughts.
Angelo


ANSWER: Angelo, thanks for the detailed photos.  They are very helpful in diagnosing the reason for your plant's ill health.  The first photo clearly shows scale insects on your plant, the second photo also shows scale and mealy bugs.  The third photo shows leaf damage due to these and possibly mite damage as well.  There is also evidence that these sucking insects have already spread to one or more of your other plants.

Only one of these types of insects is difficult to treat when the infestation is severe (as in your case), but to treat all three types is even more challenging. The problem is that some insecticides treat scale or mealy but not mites, etc.  You may want to google these insect names so you can recognize them.  Recognizing them is crucial to determine the extent of the spread within your orchid collection.  Isolate any plants that do not appear to be infested to protect them.  Place all plants needing treatment together. You will need to use a systemic insecticide.  A systemic is absorbed into the plant tissues so any insect feeding on them will ingest the poison in the plant sap they eat.  You will need to read the label carefully to determine which type of insects the insecticide is effective against.  You will be focusing on mealy and scale insecticides.  Mites attack primarily in dry conditions so as your humidity improves these should be less of a problem,  Some systemic insecticides are in a powder or granular form and get absorbed throught the roots as the plant is watered.  Other types can be sprayed on the plant but you need to be careful to avoid inhaling the mist from your mister if you choose this type.

Understand that your plants have suffered severe damage from these insects and that they are lodged under sheaths and in crevices as well as on the surface of tissues--  on top and underneath. You will also have them in your potting mix in the form of eggs, larvae, and adults so repeated applications will be necessary. Before applying your insecticide, you will need to remove all leaves, sheaths, and places where they can hide.  This will get rid of many of the critters. I recommmend removal of the plant thus so stripped from its pottting mix and place it into an insecticidal drench (ie into a pail of properly diluted insecticide) for an hour.  Be sure to use chemical gloves for all work with these insecticides.  Then repot your plant in fresh orchid potting mix in a clean pot and place in isolation from your other plants not yet treated.  Then add a dry systemic insecticide to the potting mix and water it in.  Do this with each plant so infected.

I know this seems like a lot of work with hazardous chemicals but these are persistent pests and are likely to reappear if not totally eradicated.

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

QUESTION: Wayne, I just checked in my garage and I do have a Systemic Insecticide called Hi-Yield Cygon 2-E which treats scales, mites and aphids according to the label.

I have taken all the plants, pots and all and placed them into a large bucket along with the insectice + water solution; I will leave them in there for at least one hour.

Question: Should I cut the leaves off OR will the insects dissapear once I take them out of the solution?

How often should I treat for these? I rather do preventive dipping in insecticide rather than wait until it may be too late.

Thanks again for your help.
Angelo

Answer
Angelo, Cygon 2E is certainly effective but be careful handling this stuff.  I know that I had some years ago and then I heard that they took it off the market because of its toxicity.  I believe I took all mine to a place that disposes of toxic chemicals so I haven't used it in years. I can't remmember if it's a contact insecticide or strictly a systemic.  Systemics take time to get into the plant tissues to be effective from the inside.  Contact insecticides have a more immediate effect by killing any insect upon contact.  Most systemics are effective for about six weeks. If, at that time, you still see signs of insects, you may retreat.