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!
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Yellowing and Blackening Leaves
Q. I recently repotted this Schombocatonia Jamaica Fire and suddenly this happened. I feel like the whole plant is infected. No leaves are immune to the spots. The leaves are firm, not mushy. What should I do? I have Banrot that I can use.A. It's probably bacterial, possibly black rot. I think you're going to have to resort to radical surgery. Pull it out of the pot and cut away all the older damaged tissue. When you've got it all cleaned up, lay it out on newspaper dry and get a soft paint brush and dust the plant with Banrot. After 2 or 3 days of dryness, you can repot it, or it would do well on a mount. Good luck! (Aug-26)
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Rot from Water Pocketing
Q. I hate when the heavy rain gets into new leads in this heat. The bacteria go like gang busters and I had to cut three leads today. To combat this I have to split the sheath that wraps the terminal leaf(s) so that the water drains out of the sheath. I only can do that after the leaves have started to flatten. Have you ever treated new sheaths with dilute antibiotic to set back bacteria?A. I've heard of pouring a little hydrogen peroxide in the crown of phals after watering to prevent crown rot, you could try that to prevent bacteria from destroying the new lead. Antibiotics like streptomycin and oxytetracycline are used for bacterial blighting in pome fruit trees, shrubs and some ornamentals. (Aug-26)
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Blackening on Cattleyas
Q. The leaves and pseudobulbs on these cattleyas are soft and squishy, and it is spreading fast. What do I do?A. You will have to cut away all the damaged tissue, and then spray what's left of the plant with copper. Excessive leaf wetness is an invitation for bacterial and fungal infections. (Aug-26)