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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Phal Leaf Yellowing
 

Phal Leaf Yellowing

Q. I received this orchid for Christmas 2017. The ivory and purplish flowers dried up and fell off about late February/early March. I water sparingly and have it just inside of an east facing window. I fertilize every 2 weeks. No direct sun and medium does not feel wet. Now I have a yellow leaf?  

A. I wonder if your phalaenopsis orchid is getting enough moisture. They should be watered thoroughly when you water, so water runs out the bottom of the pot and water it some more, to make sure everything gets good and wet. Then, you don't water again until it approaches dryness, but you don't want it to become dry. You can stick a pencil or bamboo skewer into the pot about 2 inches down, and if it comes back wet, you're good; if it comes back dry, you waited too long to water. If you can, you should summer outdoors too, in some protected spot where it won't get rained on to prevent the water from accumulating in the crown of the plant and rotting. It loves the breezes and cooler night temperatures and will really thrive if given a summer vacation from the house, an eastern exposure would be great!   (Jul-18)


Cattleya Leaves Are Blackening

Cattleya Leaves Are Blackening

Cattleya Leaves Are Blackening
 

Cattleya Leaves Are Blackening

Q. Is this black rot on my orchid? I'm afraid it has spread to the point that the whole plant should be destroyed. It looks like it has spread to new growth. I'm a novice at growing orchids, what I have I inherited when we bought our house.  

A. I don't think that's black rot. Black rot more typically comes up through the pseudobulb into the leaf rather than the leaf down, although it can certainly happen that way. It is also very very fast, killing the growth within a day or two. Your youngest growths definitely have something that is rotting and is black, but I don't think it is the virulent Black Rot.
    More likely, the plant was left out in the rain and the excess leaf wetness allowed bacteria to proliferate. Remove the damaged leaf immediately as well as the portion of the other leaf to about 1 inch below the discoloration. When you're done cutting, pour some hydrogen peroxide over the entire plant and move it under cover when we have rainy weather. The black at the base of the new growth is pretty normal, that is just the papery sheath dying off.
    That bark the cattleya is planted in looks to have broken down and when the media rots, the roots rot. I would knock it out of the pot and wash all the broken down media away from the roots. You can then drop the plant into the empty pot while you are contemplating how to repot it. Do you have anyone that can help you find the proper mix and repot? A friend, a nursery that grows orchids or the local orchid society would be good resources, just spray the roots every day until you get it repotted.   (Jul-18)


Blisters on Phal Flower Stem
 

Blisters on Phal Flower Stem

Q. I have "blisters" on the stems and leaves of my phal that are easily brushed off the leaves. The leaves seem to be limp in spite of normal watering. I don't see pics of orchid diseases like this online.  

A. That sure looks like one of the soft scales. Get a Q tip and some isopropyl alcohol and rub away any scale you see. Then get a spray bottle with alcohol and spray every place they could be hiding, like between the leaves. And the flower is about finished, so cut it off and repot the orchid in fresh mix because that scale can live on the roots in the potting mix too.   (Jul-18)


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