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!
 
Black Marring on Flower

Black Marring on Flower

Q. I sent pictures of this orchid to the vendor, who told me it was thrips. I have many blooming orchids in my greenhouse and no other flowers have been affected. If it was thrips wouldn't other flowers be affected?
A. Thrips are evil, it probably had thrips hidden in the buds when you brought the plant home. You can spray buds and flowers with Orthene once or twice a week if you notice floral damage from thrips, or drench the pots every 6 weeks or so with an Orthene solution.   (Jul-19)
 
 
Brown/Black Splotches on Leaf

Repotting Bifoliate Cattleya

Q. Is it too late to repot this Cattleya?
A. People live in fear of repotting amethystoglossa! The roots are long enough that they will branch if broken, so you can repot. But think of doing it Keith Davis style where you situate the plant in its new home on styrofoam, lava rock or some other airy substrate and then just put in a handful of media, so you can watch for the roots to branch and when they do, you add a handful of media every week into the pot so the new roots will grow into the new mix.   (Jul-19)
 
 
New Cattleya Lead Rotting
New Cattleya Lead Rotting

New Cattleya Lead Rotting

Q. My Lc. Blue Boy (C. Ariel x Lc. Elegans) had what appeared to be a healthy new growth. Several days ago I noticed a drop of ink black liquid on the tip. The following day there was some more. Yesterday the growth was black and mushy. The leaves all appear to be healthy. I repotted it and cut off the affected parts. There is still another new growth which I hope will develop normally. What am I dealing with? I corrected my potting issue with a shallower pot, mixing in aliflor and charcoal along with large orchiata. I grow all my orchids outside under palms and large oaks and the rest of them are thriving!
A. I'm guessing you had some water in the crevices of the new growth and it got a bacterial rot. I remember Keith Davis' tip on growing bowringiana, where he said he takes a plastic pill cup and puts over the new growth til it gets a bit larger to prevent rots. I don't think it had anything to do with the potting mix or roots. A peroxide spray might help too, after rain with new growths starting.   (Jul-19)