Orchid Culture - Questions & Answers from This Month

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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!
 
Oxalis in Orchid Pots

Oxalis in Orchid Pots

Q. I decided to try the Bonide Chickweed, Clover and Oxalis weed killer. It did a pretty good job. The sprayer it comes with is not that great and it seems like you need to get good coverage on the leaves for it to be effective. So I tried a fine mist sprayer from RePotMe.com and it worked much better Thus far, I have not seen any negative effects on the orchids.
A. That's great information. I had to buy from EBay because the local stores didn't carry it and Amazon wouldn't ship to my location. I'll try that on the oxalis growing around my stanhopeas, they have resisted everything I've sprayed on them.   (Jan-22)
 
 
Dendrobium Needs Repotting

Dendrobium Needs Repotting

Q. This dendrobium has really grown. It has been in this pot for the past three years and is growing out of the pot. How should I repot it and how much bigger the pot should be?
A. You may consider just dropping it into a larger pot. If it is currently potted in bark, you might want to jet out all the bark you can by turning the plant and pot upside down and spraying the media with a hand nozzle set to jet. Then just drop it into a larger pot and let the roots grow into and around the new pot. (Jan-22)
 
 
Cercosporoid Fungus on Cattleya
Cercosporoid Fungus on Cattleya

Phalaenopsis Leaf Blemish

Q. I'm having an issue and can't seem to identify problem. It seems to be moving throughout the plant.
A. I think that is one of the Cercosporoid fungi. You can see a pentagonal blotching in the leaf discoloration. It is really pervasive in dendrobiums. You'll have to remove the damaged leaves to remove the source of inoculum from your growing area. I suspect the cooler nights we've been having caused condensation on the leaves which helps the fungus develop. More air movement, less leaf wetness and spraying during danger periods helps. Daconil and Pagaent are highly rated for it, you can use Thiomyl or Banrot in a pinch.   (Jan-22)