Orchid Culture Questions and Answers
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Orchid Culture - Questions & Answers from This Month
by Sue Bottom, from the St. Augustine Orchid Society Newsletter
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Black Pitted Spots on Cattleya

 

Black Pitted Spots on Cattleya

Q. I have a C. percivaliana that has black, pitted spots on the old leaves and Iím concerned this will spread to the new growth. The plant is flowering now with 4 beautiful lavender blooms and I donít want to upset it. It had a couple of bad years and just now seems to be recovering. Should I remove the tips of the leaves and treat them?  

A. That looks like bacterial brown spot, a slow moving bacterial disease in mature cattleyas. I wouldn't cut anything off. When it's done blooming and you get ready to repot it, you can cut off all the old ugly stuff and pot up the front half. It'll look brand new!   (Apr-19)


Spots Spreading on Phalaenopsis
Spots Spreading on Phalaenopsis
Spots Spreading on Phalaenopsis
 

Spots Spreading on Phalaenopsis

Q. I've had this phal for 20 years and don't want to lose him. The problem started with one leaf and now has quickly spread to multiple leaves. Any ideas?  

A. It looks like it started with sunburn, that's the circular dark spot. Then maybe a secondary infection kicked in and spread into the leaf. Also looks like it hasn't been repotted in a while so I would wonder about the condition of the roots. I would cut off the extremely damaged leaves about an inch below the discoloration with a single edged razor blade. Then I think let it keep blooming and enjoy it. Somewhere in the June time frame, it'll be time to cut off the blooms, repot the plant, allow it to recover from the transplant shock, grow new roots and then bloom for you next year. Your local orchid society can help you.   (Apr-19)


Cymbidium Repotting
 

Cymbidium Repotting

Q. This cymbidium is over 10 years old, repotted once, and now huge! Itís growing more spikes and bigger flowers this year than ever before. It grows outdoors by the pool inside screen enclosure full sun. Iím wondering if I can just find a bigger pot and repot without breaking it up?  

A. What a show your cymbidium is putting on! Harry, the Cymbidium expert, had this to say: If most of the bulbs have leaves, consider potting up to a bigger pot. Best not to over pot so get a pot with one to two inches of growing room all around the pot. Pull the plant out of the pot and inspect the roots. If the roots look healthy just wash out as much of the old media as you can if it is an organic media. If it's hydroton or some other inorganic media, just pot up without washing out the old media.
  If there are a lot of leafless backbulbs, you should divide it before repotting. If you find a lot of dead roots you will need to dry the plant so you can separate the roots easily (maybe easier is the word), cut off 1/2 of the root ball. It sounds drastic but the rot will continue and is not good. Cymbidiums grow new roots quickly. It may destroy the plant if the rotten roots are not cut off. Remove as many of the rotten roots in the remaining root mass as is practical. Spray the cut area with a fungicide (Daconil or Thiomyl) and repot.   (Apr-19)




 
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