QuestionQUESTION: I've had a white phalaenopsis for about 5 years and it has recently developed black spots on the tips of two of the leaves on one side of the plant only. The bottom leaf on this side does not have a black spot but is getting lighter in color. The next two leaves are the ones with the black spots, only at the tips. Is this a fungus of some sort?? How is it best to treat this?? I have another phaleaenopsis sitting next to the white one. It is a couple of years old and also had no problems until recently. A couple of the leaves on one side have turned yellow and I cut them off. Can you please help me out here?? I am somewhat distressed as I love these two plants and would hate to see them die after such a long time. They are both in bloom at the present time. I really appreciate your feedback on this. Regards, Sharon PS, sorry but I'm unable to attach an image.
ANSWER: Sharon, thank you for your question. You did not mention when these plants were last repotted. It is generally recommended that phalaenopsis be repotted in a special orchid potting mix after each flowering. Among other benefits provided by repotting is the removal of minerals which have accumulated in the old potting mix. This build up of minerals is first noticed at the root tips with the symptoms you have described. If the plants have been repotted in the past year or so, they need to be flushed every couple of weeks with pure water (eg rain water) to help dissolve these minerals. Neither the repotting nor flushing will correct the damage done, but, will limit further damage. In addition to these mesures, reduce the concentration of your plant food and your frequency of feeding. Leaf yellowing could be a sign of root rot which is also related to a degraded potting mix. Were you to repot, you will probably find a root or two that are mushy (signs of rot). These should be removed before repotting in fresh potting mix.
Orchids need air movement through the potting mix (in the wild the roots are often exposed to the air). That is why fresh orchid potting mix is so important-- to allow more air movement to the roots. The best orchid potting mixes are based upon fir bark which, when dry, repel water or absorb it from the roots. For this reason, it is good to soak it for a few hours prior to use. Be sure to use pots with lots af drainage holes and never let the pot sit in water.
---------- FOLLOW-UP ----------
QUESTION: Thank you for your help Wayne. Actually, I have NEVER re-potted these plants--didn't know it was necessary. All I have done is run water through them once a week.
I will have to find a place to purchase new potting mix and figure out how to re-pot them.
Should I cut the spots off and spray the leaves with hydrogen peroxide and then dust the spots with cinnamon as has been suggested to some other people who have reported this kind of leaf damage?
Thanks again Wayne.
ANSWER: The suggestion on spraying with hydrogen peroxide after cutting off the spotting and dusting with cinnamon sound good. Do it early in the day so the leaf surfaces are dry by nightfall.
Once you have some of the fresh orchid potting mix, I can walk you through the steps I use in repotting. Just let me know if you would like my help.
---------- FOLLOW-UP ----------
QUESTION: Wayne: I should have also asked whether or not I should do the re-potting now or wait till the flowers drop off? It will probably be a month still before the flowers are finished.
If you advise me to wait, should I do the spot removal and treatment now or also wait until I do the re-potting?
Regards,
Sharon
AnswerI would wait to repot until the plant has finished flowering. In the meantime, grow the plant much drier. I suspect the plant has some root rot which will be promoted by growing it on the wet side. Old potting mix breaks down over time and becomes more soil-like. This restricts the flow of air to the roots and tends to remain too wet.
You could try to do the treatment now but be careful not to get the hydrogen peroxide on any of the flowers.
