Orchid Culture Questions and Answers
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Questions and Answers from 2017
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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Dripping Sticky Stuff from Phal
 

Dripping Sticky Stuff from Phal

Q. I have 6 orchids that all seem to have a sticky deposit on the leaves. The sticky stuff drips onto the table they stand on and the windows they are next to. I did try gently just wiping the leaves with damp tissues, but it all reappeared. There are no evident creatures but I note that there are now brown patches on the underside of some of the leaves.

A. Those little brown spots are scale, they are in fact sucking insects pulling the plant sap out of the leaves. Get a bottle of isopropyl alcohol, pour a little into a cup, get some Q-tips and get to work, rubbing the scale off each leaf, upper side and underside of each leaf. Then pour some alcohol into a spray bottle and spray the alcohol into the crevices between each leaf to kill anything that is lurking there unseen. You may have to repeat the spraying weekly for a couple of weeks, then just watch for reemergence of the scale.   (Apr-17)


Cattleya Sheath Doesn't Develop
 

Cattleya Buds Doesn't Develop

Q. I inherited several cattleyas that a friend purchased at an orchid show. Iíve had them a couple of years now, and had two instances of overwatering from which they have somewhat recovered. Several times the leaves have produced what I think is the flower sheath, but it never flowers, just eventually sort of yellows and withers away. Any advice?

A. Sometimes immature plants or plants growing in low light don't have enough energy to produce flowers so they produce a blind sheath, one that never blooms. If your friend purchased the plant at an orchid show, I would presume it was purchased in flower which suggests it is a mature plant. Next question, is it getting enough light to generate enough energy reserves to be able to flower. If you are growing indoors, it is often not bright enough for cattleyas. Do you have a sunnier location it can be moved to (not quickly for fear of sunburn!) or is there a place you can put it outdoors when it warms up where it is protected from the midday sun but bright the rest of the day? In strong growing plants, there are some that bloom from the green sheath when that growth matures and some that rest after the growth matures and after several months of resting the bud forms into a flower. Don't give up, you just may have to experiment a bit to get the cattleyas into bloom, but they're worth it!   (Apr-17)


Leaf Mottling
 

Leaf Mottling

Q. I have leaf mottling on some plants. I have been told that the problem was either caused by cold spells for which I was not prepared, or a nutritional deficiency. What do you think?

A. I used to get that leaf mottling on my cattleyas, patches of lighter and darker green. I think the root cause is magnesium deficiency that shows up when plants are stressed from exposure to too hot or too cold temperatures that damage the chlorophyll. Magnesium is a major component of chlorophyll and the leaves that develop with insufficient magnesium are more susceptible to damage. Our water in Florida is very magnesium deficient, mine for example has about 150 ppm calcium and only 7 ppm magnesium, far from the recommended 2:1 to 4:1 ratio. of Ca to Mg you're supposed to have. You probably need at least 20 ppm magnesium and Tom Sheehan's study indicates 50 ppm Mg is optimum for cattleyas. I use Epsom salts with every watering/fertilizing and strive for around 30 ppm Mg. Get your water tested so you know what you're dealing with and then you can figure out what magnesium supplement would be compatible with your fertilizer. You may not reverse the prior chlorophyll damage, but you can prevent it from showing up on new leaves.   (Apr-17)


B. Little Stars
 

B. Little Stars

Q. I was hoping you could identify this orchid for me.

A. That looks like a B. Little Stars, a primary hybrid between B. nodosa and B. subufolia. It is incredibly well grown and flowered. Congratulations on your beauty.   (Mar-17)


Sick Catasetum pileatum
 

Paphiopedilum Roots

Q. I bought this Paph. primulinum in October. It just fell and before I repotted it I took these photos. The orchid looks great but there are NO green roots and there is no new root growth either. What are your thoughts? It is planted in Orchiata and Styrofoam.

A. The roots look darn good to me! Paphs are semiterrestrial so they have hairy roots more like plants that grow in soil. They do have a greenish whitish hairy root tip when the roots are lengthening. If they feel plump and hairy, they're healthy. Courtney swears by adding a teaspoon or two of dolomite to the top of the pot a couple times a year, and he grows great paphs. They're also one of the few orchids that don't seem to suffer from repotting, in fact they kind of enjoy it!   (Mar-17)


Encyclia Bulbs Yellowing and Leaves Dropping

 


Encyclia Bulbs Yellowing and Leaves Dropping


Q. My Encyclia cordigera suddenly, within a week, dropped two leaves and two pseudobulbs started to turn yellow from the apex to the base, with a brownish tone also. The affected pseudobulbs look shriveled. Right now there isn't any foul smell. What could be happening?

A. It looks like some sort of rot, as you obviously suspect when you say it has no foul smell. Are the yellowing/browning bulbs hard or soft where it is discolored? If the bulbs are hard, you would think perhaps Rhizoctonia root rot although that typically happens when the mix turns sour and of course your plant is on a mount. Are there any live roots attached to the dying bulbs? Your roots look good, so I'm guessing Rhizoctonia isn't the problem. It's probably more worrisome that the next two bulbs have leaves yellowing, so you would suspect that the infection, whatever it is, is travelling up the rhizome and travelling fast. The speed with which it's moving makes you think it's one of the water molds rather than Rhizoctonia, which is typically very slow to progress.
  If it is one of the water molds, also called black rot, your friend is your shears, you'll have to cut away all the infected tissue. You can pour hydrogen peroxide over what's left and if you have one of the good fungicides like Subdue that is labelled specifically for Pythium and Phytophthora, drench what is left of the plant with it. It's really a shame cause the new growth is so nice and healthy and should have been in bloom soon. (Mar-17)


Fill Tea Bags with Organic Fertilizer
 

Fill Tea Bags with Organic Fertilizer

Q. How do you fill your tea bags with the Purely Organic fertilizer? I put mine in seed trays open, fill all through a funnel and then close.

A. That looks like a good way. I like it when my Stepmom is in town and she fills them up for me. She just scoops up the Purely Organic with a 2 inch plastic pot and pours it into the tea bag. I got the large bags last year, but I like the size of your tea bags better.   (Feb-17)


Bulls Eye Spots on Leaves
 

Bulls Eye Spots on Leaves

Q. I grow phalaenopsis orchids indoors in Pennsylvania. I have some that have tiny lighter, round spots on the leaves that seem to have a dot in the center. I have sprayed them but it doesnít seem to make a difference.

A. I am a bit stumped, that bullís eye pattern of damage looks like thrips damage where the thrips pierced the leaf and the sunken spot formed around it, but I wouldnít expect thrips in your home in PA in January. Brook wrote back that leaf damage is not new and she suspected thrips from when the window were open in the summer, as she had thrips in the herb garden and in the potato fields.   (Feb-17)


Rehab or Discard Plant

 


Rehab or Discard Plant


Q. The leaf and plant look limp and it has dark spots and white fluffy things. Is there some way to save this plant, or should it be disposed?

A. You have several things going on. The white fluffy things are mealybugs, and they are very difficult to get rid of. For a household cure, you can spray the tops and bottoms of leaves and all leaf crevices with isopropyl alcohol each week, for at least a month. The ;leaf limpness means the plant is dehydrated, which means that it is either not being watered frequently enough or the roots have been damaged and cannot take up water, this often occurs when the potting mix starts to degrade. Youíll have to knock the plant out of the pot to check the roots to determine the problem. The browned and necrotic part of the leaf is dead, and this could have been cause by several things, like water pooling on the leaf, sunburn, etc. Whether you choose to rehab this plant or discard it, you may want to understand what caused the problems so you can prevent them from happening in the future. (Feb-17)


Too Long Phal Flower Spike
 

Too Long Phal Flower Spike
Q. This healthy phal keeps producing more blooms from the ends of the same spikes that had other blooms earlier. One spike now must be 2 ft long. What do I do, cut it or just keep letting it sprawl?
A. That is a decision only you can make. Some of the phals will just keep on blooming, but you enjoy the flowers less and less because they are presented poorly. By keeping the old spike, the plant doesn't redirect its energy into producing a new spike where the flowers might be better arranged. I tend to cut the old or unmanageable spikes down at the base rather than waiting for them to throw off one of two new blooms. The plant takes a little break from blooming and then forms a new flower spike that I can really enjoy. Other folks won't cut the spike if it has any flowers. If you decide to cut, put the spike in a vase and enjoy it for another week.   (Jan-17)


Thick Small Leaves on Phalaenopsis
 

Thick Small Leaves on Phalaenopsis
Q. A friend has many phalaenopsis rescued from her office and now in her greenhouse. Some have new leaves that are stiff, green, and very thick, but smaller than the older leaves. They look like they are on super steroids, whatís going on?
A. If the new leaves are smaller than the older leaves, your plant is telling you that it is getting less of what it wants than it used to get. I'm guessing it's purely a cultural thing, nothing to do with pests or diseases. She repotted them from moss into bark, and roots acclimated to the moisture retentive moss will not thrive in the drier bark mix. Some growers add maybe 10% long fibered New Zealand moss to the bark mix to make the environment more amenable to those plump healthy roots that grow in moss. If she repotted 6 months ago, there has been enough time to reestablish the root system, gently tug on the plants and see if they are firm in the pot. If not, knock one out of the pot and take a look at the roots to decide on a course of action, perhaps top dressing the pots with some moss or a monthly dose with seaweed or some other root stimulator can jump start root growth. That bark looks very dry, it may just be a simple case of watering more.   (Jan-17)


Yellowing Leaf on Dendrobium
 


Yellowing Leaf on Dendrobium

Q. I am fairly new to dendrobiums and I was recently given a Den. Mangosteen (Den. Dark Red x Den. Suzanne Neil). I repotted the orchid into bark with proper drainage and noticed the roots, while numerous, were white and some very thin and string-like. I watered and weakly fertilized after repotting since it was very dry. Some leafless canes were yellow at the tips, one of the leaves on another cane was starting to turn yellow and some of the leaved canes were also developing a yellow color at the junction between segments. I am not entirely sure if this orchid goes dormant or if itís sick.
A. That is a very complex hybrid you have. Its parentage is mostly phalaenopsis and spatulata section dendrobiums, neither of which require a winter rest, plus a dab of the dendrobium section dendrobiums that do. How much of which genes sorted into the plant you have is a big question mark. I'd guess it doesn't require a deep winter sleep but most dens slow a bit in the winter so you donít water or fertilize as much.
  As to the roots, it sounds like the roots were not in great shape when you got the plant. When you say very thin and string like, I think you are saying that the spongy velamen layer was absent and you saw only the wiry filament. Perhaps add a little root stimulator or seaweed when you water to help the plant recover from repotting.
  As to the yellow, many of the dendrobiums with this background lose the leaves on the older canes although they often continue to bloom from the leafless cane. Yellowing is probably not good but I think a more important diagnostic is whether the cane is hard or soft. When it starts to soften, that is when the plant is starting to go south. Sometimes water or dew can pocket on a new leaf causing it to be shed, or maybe the plant didn't have enough hydration to hold the leaf. I don't think I'd be overly concerned, there's no black marks or streaking so whatever is causing it is likely caused by some environmental condition. The rest of the leaves look healthy. Keep on doing what you're doing and just keep an eye on the plant. I bet the flower is going to be fantastic! (Jan-17)


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