Orchid Culture - Questions & Answers from This Month
by Sue Bottom, from the St. Augustine Orchid Society Newsletter. Email us with any orchid question. If we can't answer it, we'll find someone who can! Send photographs too!
Bruise-like Spots on Cattleya Leaf
Q. I have looked at many photos of leaf problems but cannot find one that resembles the problem I am having. These bruise-like spots are only on the topside of the leaf, the underside is perfect. Are you able to identify the problem?A. My guess would be that is one of the leaf spotting fungi, possible one of the cercosporoid fungi. You have already removed the severely damaged leaf, the question is whether any spores have spread the problem. You could protect the rest of the plant by spraying with one of the chemicals effective on leaf spotting fungi, such as thiophanate methyl (trade names include Banrot, Thiomyl, T Methyl, 3336F). (Jan-26)
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Flowers Don't Bloom from Sheath
Q. I have a persistent issue with some flowers not coming to maturity. It's always and only in plants where the flower has a sheath around it. They form and once in a blue moon flower, but usually dry up and do nothing. Anything that gets a sheath tends to not bloom. I don't think it's fungal, spraying doesn't help. Any thoughts?A. I don't think it's a fungal issue. For the first image where the sheath is yellowing, I think what happens is moisture condenses in the sheath and rots the bud. If the sheath is green or dried, leave it on the plant, but if it gets that sickly tan to brown color, gently slit the sheath and peel it down so water won't condense in there and cause rot. I think happens mostly in the fall and spring when there is a large difference in the day night temperature. In the second picture with the dried sheath, it is possible it is natural, some cattleyas form the sheath and then rest for several sometimes many months before flowering, like a skinneri. It is also possible the plant is not mature enough or not getting enough light to form sufficient energy reserves to bloom. (Jan-26)
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Repot Mormodia?
Q. Is it time to repot this Mormodia or should I let it bloom out?A. I'm betting those are flower spikes. This is the bloom season for mormodias. You probably won't see the new growths peeking out til February or March. That's when you can think about repotting. (Jan-26)