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 Streaks on Cattleya
Black Streaks on Cattleya

 

Black Streaks on Cattleya

Q. I have some new leaves with streaks on a cattleya I have had for 10 years. It bloomed beautifully in May as usual. It is hanging under my lanai roof with a west exposure. One leaf fell off and I noticed these others have the same problem. Most of the old growth looks fine. Any ideas?  

A. I think that's bacterial on the new growths. That new growth is so soft and tender that the bacteria can much more easily invade the tissue than the older mature growths that have hardened off with a good waxy cuticle layer. It was so rainy earlier this year that I moved almost all the cattleyas into the greenhouse, only the tough schomburgkias and schombocatts were left under the shade structure. That tender growth is just so susceptible; all you can do is cut off the infected stuff. I sprayed Zerotol before and after storms and it helped, probably copper or Physan would be better, but be careful with genera sensitive to copper.   (Oct-18)


Repotting, What to Do with all these Cattleya Roots

 

Repotting, What to Do with all these Cattleya Roots

Q. I just dropped this cattleya into a clay pot rather than repotting, but decided it was time to repot. When I pulled it out of the clay pot, there are all these roots growing out of the plastic slotted basket. Now what do I do?  

A. As long as the mix inside the plastic basket is in good shape, don't disturb the cattleya or its roots. You can try water jetting out any material that you can remove, and then find a large wooden slatted basket. You may have to remove the top collar of the plastic basket so it nestles easily into the wooden basket. Get some nippers and just cut right below the solid collar, where it joins the netted basket. The basket will lose its rigidity, but it will be supported by the wooden basket.   (Oct-18)


Bare Root Brassavola cucullata

 

Bare Root Brassavola cucullata

Q. I recently bought this Brassavola cucullata bare root. Unfortunately, when I unwrapped it, the roots were all rotted. The vendor said it needs to be mounted “upside down” with the leaves hanging down. What is the best method to revive this plant? Can I still properly mount it and regrow the roots?  

A. Your first order of business will be developing new roots and you may need some rooting hormones to make that happen fast. I use Dip 'N Gro, but there are plenty of them on the market. If you want to mount it, mount it so the growths will dangle pendulously from the mount, make sure it is immobilized with a couple cable ties, if it moves while the roots are developing, they'll be rubbed away and die. You can put it in a slight shadier spot while you're waiting on roots to grow and spray it 2 or three times a day, or put a little sphagnum or Spanish moss (may be better) to keep humidity high around the roots. Once the roots attach, say 2 months down the road, you can move it into brighter light, remove excess moss, etc. If you need any help, don't hesitate to ask!   (Oct-18)


Silvered Dendrobium Leaves
Silvered Dendrobium Leaves

 

Silvered Dendrobium Leaves

Q. This dendrobium has been growing in my kitchen window (West) for the last 2 years. I recently introduced a second dendrobium into that space that had these symptoms first. I moved it away immediately and was horrified to see how fast this one's leaves silvered.  

A. That is classic mite damage. The inside growing environment is pretty dry and mites thrive in dry conditions. During the growing season, you should consider moving these dendrobiums somewhere where they get the outdoor humidity, morning dews, etc. that will help create conditions less desirable by mites. While it's next to the kitchen sink, put it in the sink and use the sprayer to wash all the leaves, top and bottom, so you will wash anything on there down the drain. You could also get a spray bottle of isopropyl alcohol and add dish washing soap like Dawn to it and when you're done giving it a bath, spritz the leaf undersides with it.   (Oct-18)


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