need help - can't find an answer anywhere

[stretch02554]

hi all,
i have looked all over the www and can't find the reason for the black spots on my dendrobium.
i found this picture in the diseases etc forum - but couldn't find a response as to what it was, and I want to treat for the correct ailment.

my dend is in bloom and two of the canes leaves are doing this. i suspect that it could be too much sunlight - but don't really know.

i would appreciate any input!

thanks!

[digitalgate]

it look like you have a dendrodrum. It look like it has been in full
sun for 2 or 3 day. You might need to provide some shade for it. Not all
dendrodum can handle full sunlight. I have harden my dendrodum for full
sunlight. Try not to expose the plant to rain water. It might be a source
of your bacteria or fungus infection.
[IMG][/IMG]

[mbasden]

if you have the plant in a hanging basket it may be rubbing on the metal hanger. This may cause some problems with spots and infection. An area that has been rubbed may be a way for infection to enter the leaves

[Cynthia, Prescott, AZ]

First, you must realize that most Dens don't hold their leaves very long, with the lower leaves shed fairly early sometimes when the upper ones may last several years. The length of time Den leaves last vary greatly from Den to Den. So, before you get all upset, look at the plant. Are these older leaves? Are they lower leaves. Compare the newer growths to the older growths. The picture shown above looks like normal senescence to me.

[stretch02554]

Thanks for all of your input. Sorry to have upset Cynthia with my total ignorance.

[Cynthia, Prescott, AZ]

Did I sound upset? Dear me, I have done my best in recent years to be patient with all questions orchid related. Please be reassured that I welcome all questions from beginners, no matter how simple they may seem to me. I know they are not simple for you. I know that the leaf loss on Dens is probably the biggest worry newbies have, and unnecessarily so. I wish we could have a blinking neon sign on the site. DENS NORMALLY LOOSE LEAVES IN FALL AND WINTER _^_^_^_^_^_^_^, so you could get the message immediately and save you unnecessary worry. For me, I may repeat the same advice many times, but we have a great group of people here, and often they do a good job with all the newbie questions. You'll find that friendliness and patience abounds on this site.

[dionysus]

yeah, either it's a virus or bacteria. i read that 24 hr light or full sun light can weaken the immune system of some orchids. try giving it some nutrients and isolate it from any othre orchids in case of infection.

[Cynthia, Prescott, AZ]

Not bacterial if each spot is not growing rapidly in size and have a wetish quality. Don't think virus is a likely cause of spots, there are too many other causes of spots that are usually the reason. Of course, it would help to have a picture, but as I said, the most common cause of spots in Dens this time of year is old age of the leaves (senescence).