Orchid Culture - 2024 Questions & Answers

Cattleya Bulbs Browning from Rhizome Up

Q. This cattleya is potted in a small bark mix and is growing outside. Do I need to apply fungicide?
A. You've got something really nasty coming up from the rhizome into the pseudobulbs. Your best treatment will be your shears. Knock that plant out of the pot, and cut away all the discolored bulbs. Look at the base of each bulb, and if you see a yellow, creamy coloration, or if it has progressed to brown/black, start cutting. Sterilize between cuts until you only see green tissue. I'd probably leave it out to dry on some newspaper for a couple days and reinspect to make sure that none of the remaining plant has discolored tissue. After that, you can repot. If the plant is pretty small after surgery, you can try dropping it into a clay pot and misting it daily until roots start growing, and then pot it up.   (Sep-24)

Black Sunken Spot

Q. This is a nobile den. This black spot has been present for a while but now it's on other leaves.
A. I would guess that is bacterial blighting, with the sunken spot and you can see the yellowing around the sunken spot where the bacteria is dissolving cell walls in its advance. This problem is probably related to all the rain causing excessive leaf wetness. You can just remove the affected leaves. You may want to consider some preventative spraying during the hot and wet summer months, weekly with something like consan or pool algaecide.   (Sep-24)

Habenaria Growing Down into Moss

Q. Only one habenaria corm has life. I checked for roots today only to discover there are no roots. What I thought was a root is actually the plant growing straight down into the spaghnum moss. Now what?
A. It looks like you had the tuberoid turned upside down when you potted it, it happens to the best of us! Use a tall pot, put 1/2 to 1 inch of perlite in the bottom of the pot followed by some sphagnum. Situate the tuberoid so the top of the tuberoid where then plant is emerging is about 1/2 inch or a little more below the top of the pot. Then fill with sphagnum around the tuberoid to just below where the leaves are forming. Wait for roots to emerge from the top of the tuberoid and for the first rosette of leaves to open before watering. As the plant continues to grow, you may be able to place a little more sphagnum around the top for stability and to protect the roots that grow from the top of the tuberoid. Here's an article: If You Can Grow Potatoes, You Can Grow Habenarias.   (Sep-24)

White Spots on Cattleya

Q. Are these mites on our cattleya?
A. That is scale, and a pretty serious infection. You can water blast it off, spray with alcohol and wipe it off, etc. But, you won't get all of it off. You'll have to spray or drench with a suitable pesticide afterwards. Good luck!   (Aug-24)

Should I Worry?

Q. Can you tell me if I should worry about thus Aliceara that I just received as a gift from Palmer? These brown spots on the leaf tip are new.
A. I wouldn't worry, but I'd cut the leaf off about an inch below the discoloration. If it was sent through the mail, it could be heat damage, or perhaps something bacterial, but in any case, sanitize the plant by removing that portion of the leaf. Then, you don't have to look at it and you don't have to worry if something is going to spread from that area to the rest of the plant. (Aug-24)

Sunken Yellow, Tan and Brown Spots on Phal

Q. In the last year or two, my Phals have been devastated with some kind of problem. Even brand-new orchids bought in develop this issue eventually . I have been spraying now for 2 months with Neem Oil and Physan. New leaves don’t show this disease until they start to mature and then it comes on full bore. They all have bloomed without fail and with no virus streaking. I have checked the orchids and there are no white flies, mealy bugs or red spider mites. The roots are healthy. Do I just throw everything out and start again or will the spraying do its thing eventually.
A. Those leaves look really rough. My worst fear would be that the damage on the phals is caused by Orchid Fleck Virus (OFV), which is spread by tiny little mites in the Brevipalpus genus (Tenuipalpidae). Here's a link to Hark Orkideen that shows images of OFV on phals remarkably similar to the pics you sent. I'm not aware of any lab in the US that can test for OFV, and of course, there is no cure for OFV. Neem oil and physan will likely have little effect on this problem, you need a miticide. Not all miticides can control this type of mite, probably the most inexpensive of those that do is Avid, with the active ingredient abamectin. With the way it has spread, I think you should get some miticide effective for this type of mite and spray your entire collection, top and bottom leaves, and repeat at 2 week intervals, following all label instructions.
    It's also possible it is some sort of fungal issue, like fusarium. Waypoint Analytical in Anaheim, California can test a sample for around $150, you might try and contact them if you decide to try to quantify the issue. I would say my top suspicion is OFV, with fusarium or one of the bulb/stem/root rots as a distant second. (Aug-24)

Bottom Phal Leaves Yellowing

Q. Late last summer I learned the hard way that afternoon direct sunlight can seriously damage orchid leaves. As the attached photos show, two of the bottom leaves of this pretty healthy orchid got severely sun-damaged. I thought it best to leave both damaged leaves on the plant until they fall off, but they are still in place now 7-8 months later. Is it best to carefully cut them off, or should I continue to wait until they fall off?
A. I don't think those leaves are sunburned at all. Sunburn, when it happens, occurs on the highest point of the leaf where the light hits the leaf at the most direct angle, perpendicular to the leaf. What you're seeing on your healthy phal is that the lower leaves are dying off, to be replaced by new upper leaves. If there is anything that is concerning, it is that the newest leaf seems smaller than the other leaves, but of course it may still be growing and filling out and it may still grow the same size as the others. If it doesn't, however, it suggests that the plant is not getting something that it was getting before when it grew the other leaves. Could be it is receiving lesser light, could be the bark mix is starting to degrade so the roots are beginning to suffocate, could be it is not receiving the nutrients it was receiving before? To answer your questions, don't cut the leaves, they are not diseased and do not pose a risk to the plant. As they yellow and die, the plant will reabsorb nutrients in the leaves to fuel the new leaves. When they can be removed with a gentle tug, you can remove them.   (Jul-24)

Catasetum Lip Didn't Rorate Downward

Q. Is the labellum of this catasetum yellow and sepals and petals the brown? Why did the lip not twist downward like my cattleyas do?
A. The catasetum lip is yellow and the sepals and petals brown. The catasetum probably didn't rotate the way you wanted because you tried to stake it to go upright, rather than allow it to be pendent. If it had been allowed to drape over the pot, the lips would have been oriented correctly, perpendicular to the flower spike. If you don't have it hanging, you can always put the pot on top of another pot to allow the flower spike to grow more normally.   (Jul-24)

Black Leaves on Cattleya

Q. Both of these orchids have this black disease, which travels through the leaf, top to bottom and in on case it completely contaminated the whole leaf and looks like it will do the same on other leaves that are just blackening. Do you know the diagnosis and how to treat it?
A. Some people would call that black rot, implying that it is the disease caused by one of the water molds. I think it is black and it is a rot, but I suspect it is caused by bacteria rather than the water molds. Completely remove the leaves, and spray with either a fresh bottle of hydrogen peroxide or something containing copper. I'm guessing this happened after the plants had lots of leaf wetness? One thing you can try after storms, and particularly after a tropical storm with lots of gray, wet weather is to spray the leaves with something like Consan/physan/pool algaecide. You can mix it up in a little hose end sprayer and just douse everything after the rain passes, that'll help keep the bacteria at bay. The true black rot that infects our cattleyas usually happens more in the July/August time period when the humidity is way high, and the water molds infect the plants usually from the roots up into the rhizome and then pseudobulbs. I do bimonthly drenches with Aliette/Subdue starting in May to try to keep black rot away, and also keep plants drier in the high humidity months.   (Jul-24)

Cattleya Flower Blighting

Q. Is this botrytis on my cattleya? The spots spread rapidly and are sunken.
A. It may be a botrytis fungal infection, but it seems like the splotches are too big unless it's been there for a while. With it happening fast, perhaps it's more likely that it is bacterial rather than fungal blighting. Your reaction, cutting off all the flowers and disposing of them, and then a follow up copper spray should take care of the problem.   (Jun-24)

Pot vs. Basket for Miltonia

Q. I read Miltonia spectabilis var. moreliana grows well in baskets but I don’t seem to be growing this one very well. I’ve had it 2.5 years and no blooms. Should I take it out of the basket? It looks very yellow to me.
A. It should do better in a basket than in a pot. It really likes is to grow around the outside of a pot rather than in a pot, so the basket should work well for you. Don't disturb it while it is growing so well. I think it's just got to get a little older. It is a fall bloomer, so maybe you'll get a bud or three this year. It looks like it's getting plenty of light, no problem there. You can always add time release fertilizer to your plants in the spring if you don't have the time or inclination to use water soluble fertilizers. Be patient, you will be rewarded soon.   (Jun-24)

Phal Flowers Dropped

Q. Within one week, this orchid which I purchased about 2 months ago, has dropped most of its blooms and gotten one yellow leaf. Is this normal?
A. That's pretty normal. You can usually expect a phal to bloom for three months, sometimes longer. You don't know how long it was in bloom before you bought it. Now is the time to cut back the bloom spike and think about repotting it, if it needs repotting, so it can recover from the transplant shock and start gathering its strength for next year's blooms.   (Jun-24)

Blotches on Cattleya Leaf

Q. This is my Rlc. Volcano Spring with blotches on a single leaf. Any thoughts on this disease and recommended treatment?
A. That looks like a cercosporoid infection, from one of the leaf spotting fungi. The typical recommendation is to spray with thiophanate methyl, such as in Thiomyl or Banrot. Unfortunately, the fungicide won't cure the infection, just help prevent unaffected leaves from becoming infected. You'll have to decide whether you want to remove the infected leaf, which undoubtedly contains spores that have the potential to spread the disease.   (May-24)

Rlc. Golf Green 'Hair Pig' Unruly Flower

Q. I've had a mature Rlc. Golf Green 'Hair Pig' acquired through Odoms several years ago, which has consistently bloomed, but the flowers present themselves dismally, e.g., bent, upside down, and twisted. I gave it several years, but it has never improved. This photo was taken in 2021 but doesn't convey the problem as the flower was wired in place. I hate to send it to the compost, but what does one do with a plant such as this?
A. The problem is the long pedicel Golf Green inherits from its digbyana parent. The only way I know to overcome it is to stake it early in the process, and you might have to be creative with your staking. It's a beautiful flower when it is presented like you had it in 2021!   (May-24)

Coconut Orchid Pseudobulbs Wrinkled

Q. I saw my friend's coconut orchid and her pseudobulbs are nice and plump. My pseudobulbs are wrinkled. What can I do? It is outside and gets lots of indirect sunlight.
A. That plant looks dehydrated. The two most likely causes are either it's not being watered frequently enough or the roots have rotted so it can't take up the water it is being given. Try to pick up the plant by the vegetation and see if it's wobbly in the pot. If it is, the roots aren't healthy. This orchid also has a tendency to grow up and out, so it responds really well to being grown in a basket. See if you can find a 6 or 8 inch basket for it, and pot it up. You can bring it to the repotting clinic and we'll help you with it. (May-24)

Weird Phal Flower Spike

Q. I have a grocery store no-id Phal that seems very healthy but has leaves that are significantly twisting and both its flower spikes emerged normally then started dramatically twisting even though the LED grow lights are directly above it. I am wondering if the leaves are showing chlorotic streaking and whether the plant might be virused.
A. Some phals have certain species in the background that have markings similar to what your phal is showing. That flower spike is very confused. I have tried straightening them out and all I do is break them. It's a lot twistier than what I have seen in the past, so maybe there's some genetic predisposition, or perhaps you moved them on the shelf to water them and the light orientation changed? At any rate, you'll have to wait til next year for hopefully a better flower spike. The plant looks healthy.   (Apr-24)

Catasetum Has New Growth Starting

Q. I see new growth on this Catasetum that still has green leaves, so I’m afraid to repot. Can this wait until the next potting clinic next month? Should I start watering it?
A. The best time to repot any orchid is immediately before the new roots start growing. With most orchids, you don't know when the new roots are starting until you see new green root tips. With catasetums, you know when you see the new green growth begin to form that you have a week or 10 days before the new roots will start growing. This short window is the best time for you to repot your catasetum. That catasetum has outgrown its pot, so you should repot it over the next few days.   (Apr-24)

Leaves Falling Off

Q. This Bc. Yellow Bird spent the winter in my eastern exposure bathroom. As blooms faded, I moved it to a southern exposure under my pool screen. Now almost all leaves are falling off. The leaf tips stared browning and then fell off above the pseudobulb.
A. Looks like you've got some cleaning up to do! Get a sterile tool and cut off all the severely damaged leaves, probably close to the base of the leaf. That will remove the source of the problem, which I would suspect to be bacterial in origin. Then, spray it with some copper, and put it back in the eastern exposure bathroom until it perks up. I'd guess that you have been growing in the same pot for a while judging by the density of the pseudobulbs. Try lifting it up by the vegetation and see if there's any wobble in the pot. If there is, repotting is in your future, but I'd wait a bit on this to see what dead/infected areas have to be cut out.
    Some guesses as to what might have caused it. It could have been cold exposure after it's winter nap inside, or perhaps the big day night temperature changes caused condensation on the leaf surfaces at night and this was the starting point for the disease issue, or there could have been dripping cold water from above onto the leaf surfaces also causing cold damage. I am guessing the damage happened fast rather than slow suggesting it's bacterial rather than fungal. Your normal fungicides won't do anything for a bacterial infection. The good news is these guys are very resilient, so if you can stabilize the plant, by mid summer you'll hardly know you had a problem.   (Apr-24)

Cycnoches Soft Spot

Q. I’ve treated this Wine Delight with Thiomyl and cinnamon. I was waiting until the leaves died back and hoped it would callus over. Now, it is withering. Should I pull this whole section away from the other two? I don’t want to lose the whole orchid. Should I just cut below that soft section, or is it better to bite the bullet and get rid of that whole section?
A. That is a rot inside the pseudobulb, beyond the reach of chemicals. You'll have to cut away the infection, cut until you see no discoloration on the inside of the pseudobulb. You may be able to place the uncontaminated part of the pseudobulb halfway into some sphagnum moss and see if it will sprout keikis eventually. Cut that bad pseudobulb away from the mother plant so the plant will be safe.   (Mar-24)

Habenaria Tubers

Q. These habenaria tubers are stored in a plastic bag. I'm watching for any sign of life. They have what looks like salt crystals in the tubers, which I scraped off. I have the AOS Habenaria Culture sheet and I have read the issue of SAOS 2022 newsletter that featured Habenaria. According to that sheet, I probably should put them in dry mix just in case they are alive. I will have to place them horizontally since I don't know which end is up.
A. The tubers are not dead, they are just sleeping. I am guessing what looked like crystals was probably perlite from the ProMix, and it was just grown into the tuber, probably best to just leave it attached. I think the top of the tuber is to the right in your picture. In the lower one, you can see the vestiges of the old tuber, that is now dried up and dessicated. The roots grow from the top of the tuber. None of my tubers have woken up yet, though I saw Sarah Hurdel's post where lots of hers have started growing. Just be patient and check the tubers every week or so. I'm torn too, and thinking maybe I should just start potting them up and leaving the top third of the tuber uncovered so I can finish the repotting process after they start growing, but so far I have resisted the urge.   (Mar-24)

Sudden Lesions on Dendrobium

Q. I have a dendrobium orchid that has done really well until this past week when it developed lesions (that I noticed). I treated it with Thiomyl for Anthracnose. Any ideas?
A. That looks like a cercosporoid fungus, dendrobiums seem to be very susceptible to it. You'll have to remove the severely damaged leaves that contain fungal spores. Thiomyl is a good preventative, but it is not curative, that's why you have to remove the source of inoculum.   (Mar-24)

Phal Leaves Getting Soggy

Q. The leaves on two of my Phalaenopsis plants are getting soggy. What could be the problem?
A. That's bacterial soft rot, caused by Erwinia (also called Pectobacterium). Cut away the damaged leaf quickly before the infection reaches the crown, and douse with hydrogen peroxide or a copper bactericide. Spray all the surrounding plants too!   (Feb-24)

Leaves Are Crinkled

Q. My plant's leaves are all crinkled. I water when it seems dry, and it's sitting inside with no direct sun but near lots of windows.
A. When the leaves on oncidiums get that accordion look, it means they're not getting enough moisture. You'll have to step up the watering frequency a bit. Good luck!   (Feb-24)

Gray and Brown Leaf Spotting

Q. I separated this one immediately from all the other orchids. The leaves have gray and brown spotting. Would you please tell me what's wrong and what I should do.
A. I think you probably have a mite infestation on that dendrobium. They spread pretty easily, so check your other thin leaved orchids like oncidiums; they also will go after the soft tender phal leaves. The first step is take it to the kitchen sink and wash all the leaves, top and bottom. Then get a spray bottle of isopropyl alcohol and spray the entire plant, top and bottom. You may have to repeat this weekly for a couple of weeks. Here's a link to the website, scroll down to the mites section for some other ideas. (Feb-24)

Mount Neofinetia falcata?

Q. These Neof. falcata arrived in tiny pots with loose large bark. I just mounted them on cork with sphagnum moss and removed it. Would they be safer in a clay pot? I read that the Japanese mount/plant them on a sphagnum moss ball they place in a bowl.
A. I referred this question to Suzanne Susko and Joanne Stygles, who specialize in these orchids. Suzanne wrote: Those Neos look great. The grower you got them from knew how to grow them. I use the traditional Japanese/Korean style of growing which is a sphagnum ball, but with a twist. The center of the sphagnum ball is filled with a stack of peanuts so the center of the pot gets constant air flow. The roots of the plant are contained in about ½ of sphagnum surrounding the peanuts. They need to dry out between watering, but can be in a moist environment for several days. I water only when the sphagnum is very crispy; you can easily kill Neos by overwatering. You can use two small net pots to achieve the same result. Take a small net pot inserted into the center of the roots at the base of the leaves. Holding it tight, surround the roots with about ½ inch of sphagnum. Place the whole thing into a slightly larger net pot leaving the bottom open for air flow.
    Joanne added: I grow the majority of my neo's in 3A & 5A New Zealand sphagnum moss. I place the roots on top of a 3A mound created with an air hole using a moss pole, then wrap the 5A around the roots. The effect is similar to Suzanne's method. I also have a few which are attached to cork and wood mounts. Those are not my named varieties, but rather what neo growers call Furan (wind orchids). They do well, however I find they do not grow as well or as strong. Neo's are not fast-growing orchids for the most part, and some of the named varieties take years to even make what we call a clump. You can use a regular clay pot with either small bark or loose sphagnum, cork, or traditional method. All will help you enjoy this fascinating species. To us Neo nuts, it's not a vanda, it will always be a Neofinetia falcata. I have attached a link to Jason Fischer's Orchid Limited webpage, he is one of three US based growers of Neo's and is an expert with these beauties.   (Jan-24)

White Balls Around Roots

Q. Is this a fungus?
A. I think that's one of the bad ones, Sclerotium or Southern Blight, though I've never seen it on a vanda before. Carefully remove it to the trash, all those little balls that look like mustard seeds are the resting form of the fungus, and will spread the disease readily to nearby plants. I hope that vanda wasn't one of your favorites! (Jan-24)

Inadequate Drainage

Q. I misplaced this Dendrobium in a pot with inadequate drainage. It’s in half death throws but I don’t know if I should cut anywhere or just leave it out in the air for a bit.
A. It looks like you've got rot coming up from the roots into the cane, and it looks like it's affecting all but maybe one cane. I suspect the nobile's days are numbered.   (Jan-24)