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
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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Orchid Needs Repotting
 

Orchid Needs Repotting

Q. This plant has not been repotted in years. It blooms all season, but never more than 5-6 at a time. I am content with it but was wondering if I should thin out roots.  

A. Never thin live roots. The central part of your plant has probably disappeared because the organic matter in the mix has turned to mush and rotted the roots. You may have to tackle a repot, get the roots wet and pliable, yank it out of the plastic pot and drop it into a large basket.   (Jun-18)


Bacterial Brown Spot on Cattleya
 

Bacterial Brown Spot on Cattleya

Q. What’s going on with this fella? It made it all the through the winter then bam!  

A. The discoloration on the oldest leaf looks like bacterial brown spot, so it is probably an air movement issue. Looking at the next two younger leaves, it looks like the tips were cut off, possibly because they too had the bacterial spotting. Consider cutting the oldest leaf off about an inch down beyond the yellow discoloration and think about repotting it. Bring it to the next Ace potting clinic and we'll help you with it.   (Jun-18)


Mites on Catasetum
 

Mites on Catasetum

Q. I have 60 catasetums growing in a screened room. I struggled to keep the mites under control last year so I am being aggressive this time around, but the first two catasetums that emerged from rest are already attacked. The other 12 that are already growing fast and being watered so no mite problems on them. I do not dare treat catasetums with emerging bulbs, so I have to wait until I start watering them. It frustrates me because it is indeed a lot of damage for a plant that just woke up. On top of that I sprayed Sultan on all of them when they went dormant because I am never sure if mites sleep in the root zone while the foliage is gone.  

A. How interesting. I just reread Johnson's article about mites, and he says the mites can live in the media. So perhaps what you really need is a drench instead of a spray. You can try the Bayer 3 in 1 if it has fluvinate in it. Kontos can be used as a drench, it is both xylem and phloem mobile, but it's pretty expensive and not recommended for use on orchids. Johnson recommends Avid, says it is the least toxic. Talstar or Bifen with the active ingredient bifenthrin is affordable and may be your best bet. It comes in a granular form (I use it for fire ants but the active ingredient is effective on mites), and as a liquid.   (Jun-18)


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