Steve Wilson, I am sorry to hear that all your Phalaenopsis with the problem died, especially the old one you were fighting to keep.
Anyone interested in the Phalaenopsis leaf lesion/micro fungus problem (It goes by a few names), there has been plenty written about it (especially around early 2004 when Steve brought it up) on the OGD and can be looked up in the archives, or send me e-mail and I will send you the posts. As some may know I gave a sample of a leaf to the California State Agricultural Dept. They looked at it under a electron microscope, and found nothing. The verdict: no fungus, no bacteria, and no virus. The plant pathologist opinion is that it is a physiological and cultural problem. The test was only done on one leaf from one Phalaenopsis, so the conclusion may or may not pertain to any other Phalaenopsis with this problem. I have three Phalaenopsis with this problem that I have been playing around with and trying to “cure”. After getting the results back from Cal State Ag, I tried a little experiment to see if I could “infect” a Phalaenopsis. I bought two Phalaenopsis hybrids (same size and type). I grew them for about 8 month separate from all other plants to see if they would show any sign of disease. They remained healthy. I then scooped a leaf from an “infected” Phalaenopsis with a sterile gouge. I took the scooped out part of the “infected” leaf and placed it into a scoop I had made in one of these new healthy Phalaenopsis, and secured it with tape. I continued to grow these new healthy Phalaenopsis together away from all other plants. After a year and a half, both the Phalaenopsis I intentional infected and the control showed no sign of the disease. Both remained healthy. I realize this is a n=1 experiment, but that is all I can do. I also tried to “infect” /Cassia occidentalis/, which I got from AJ Hicks, and nothing happened. /Cassia occidentalis/ is an indicator plant that catches just about everything. http://image.fs.uidaho.edu/vide/famly076.htm#Cassia%20occidentalis None of the three Phalaenopsis, I have are “cured”. They often will grow new leaves without lesions that will remain that way for sometime, but eventually lesions will form. I think the lesions are becoming less and not as crippling, but they are still there. I do think that the problem is a physiological and cultural problem. I think the problem happens in other orchids. It just looks different, like the Oncidium Sharry Baby spotting. I am still looking for a follow up to this article: In Orchids Magazine, January 2004, page 54, “What Causes Those Spots?” by Mani Skaria, PhD, Yin-Tung Wang, PhD, and Larry Barnes, PhD, they are doing a “Microscopic Study of Leaf Lesions of Oncidium Sharry Baby ‘Sweet Fragrance’. The conclusion of the article is they have eliminated a number of possibilities and are down to a virus infection or nutrient imbalance. Their next steps are a leaf mineral analysis, and some preliminary virus diagnosis. I have yet to see a Phalaenopsis cured of this problem. Nothing that I have tried culturally to “cure” the problem has worked so far. Some seem to be able to live fine with the lesions. One of my Phalaenopsis with the lesions is in bloom right now with many flowers. The fate of Phalaenopsis with this problem may very well be the same as Steve’s. Mark Sullivan In God We Trust, everyone else bring data. _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
