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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Leaf on Catasetum (?) Yellowing

 

Leaf on Catasetum (?) Yellowing

Q. Is this a Catasetum? Iím concerned about this second yellow leaf.  
A. I think that is a Grammatophyllum, a close relative to catasetums, but these don't lose their leaves in winter. They tend to be mite magnets and your plant shows evidence of mite damage. You can spray a miticide like Avid (normal insecticides won't kill mites, which are in the arachnid family) or you can water blast the leaves with a nozzle set on flat and then spray the entire plant with alcohol or alcohol with dish soap, perhaps repeat weekly for a month or so.   (May-19)


Is This a Bud?
Is This a Bud?
 

Are These Buds?

Q. Could these possibly be buds?  

A. It sure looks like it. They're called the bud primordia, the tissue from which the flowers will ultimately form.   (May-19)


Spots on Vanda Flower
 

Spots on Vanda Flower

Q. I recently purchased some more orchids (a recurrent problem) and one was a blooming vanda that had questionable spots on the flowers. If it is Botrytis, what is the best course of action? Being in west Texas, the humidity is super low, but I have been running a humidifier so itís felt much more jungle like in my sunroom lately.  

A. I don't think it is Botrytis, a fungal infection causing small dark spots on the flowers. You may have two things going on, the black sunken spots may be some sort of bacterial infection and the raised, corky spots are probably edema. Edema is like a blister when the plant absorbs more water than can be shed through transpiration, happening more on leaves than flowers. It happens when you water late in the day and the nights turn cool or when you water on a gray rainy day. It doesn't really harm the plant. Look at the spots, if they are sunken, think bacterial infection, but if raised it is more likely edema.   (May-19)


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