Orchid Culture - 2018 Questions & Answers
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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!
Brown Marks on Leaf Edges
Q. I’m having yellowing of Cattleya leaves. Mostly it is on older leaves. However, quite often the yellowing extends a lot closer to the front than I would expect from simple senescence. Sometimes it involves the second or third bulb back from the front, sparing the back of the plant - but this is not typical. Last year I took samples to the agricultural extension here in Nashville and was told it was nutritional, not insect or disease. It starts in the leaves and not in the bulbs. Generally it doesn’t kill the plant and I have even seen leads break from eyes in the affected tissue. It occurs in a patchy fashion throughout the greenhouse.
A. I don't think it's viral or bacterial, so that leaves fungal, probably one of the leaf spotting fungi. The problem with a fungus is that once it's inside the plant, it is beyond the reach of most fungicides so even if you wanted to spray, it wouldn't really help. So here's the choice, if the plant is strong enough, cut off the infected tissue and discard it, and then pamper what is left, if you want to you can spray with something to protect what's remaining. If the plant isn't strong enough to cut away the obviously diseased tissue, then just move it away from your other stuff and let it do its thing. This may be caused by Guignardia/Phyllosticta or a different fungus that we haven't previously associated with our orchids. Carole updated us "I think I can cut away the affected leaves and bulbs and still save the plant. I will cut it up and spray fungicide."
Tiny Spotting on Leaf Undersides
Q. Do you have any idea as to the problem with this Den. aggregatum? It was doing beautifully until this year. The plant lives outside under an oak tree and receives minimal morning sun.
A. The spotting on leaf undersides is likely fungal, possibly Cercospora dendrobii. More air movement would help. We've had lots of rain here this year, so the excess leaf wetness can create a conducive environment for fungal growth. You can remove severely affected leaves and spray with a fungicide like Daconil, but more air is the long term solution. Here's an interesting post
from an Aussie blogger that recommends spraying lime water for Cercospora dendrobii.
New Bag Babies
Q. Yesterday I picked up 2 bag babies.
I found this black patch on the Brassavola when I got it home. Is it black rot? What would you suggest I do?
I also notice a couple of brown patches on the pseudobulbs of the Schomburgkia orchid. I did not realize how large this plant can grow until I came home and googled it. I also read about ants living in this plant. Does it mean that ants are a given with this plant? I don’t want ants to infest my house / growing area because they are attracted to it?
A. Cut off the one leaf on the Brassavola, looks like maybe it got sunburned while being tortured in the store. It looks healthy otherwise. The Schomburgkia looks healthy too, don't know what the brown patches are but as long as they are not soft, they'll be fine. In nature, ants have a symbiotic relationship with the orchid, but they won't infest the plant in the house.
No worries, the plants are healthy and should do fine for you.
Leaf Tip Discoloration
Q. I bought this orchid on eBay. Is this anthracnose on the leaf, and if so, what should I use. I don’t want to spend a fortune on chemicals.
A. Yes, that's anthracnose, you can tell by the little dark dots between the darker bands, they are the fungal spores. Cut the discoloration off the leaves about an inch below the discoloration with a single edged razor blade. If the eBay seller sent this plant with obvious anthracnose, don't buy from them again.
Dendrobium in Sphagnum
Q. I got a dendrobium last week from the local farmers market. It has lovely blooms! But the root/pot is packed tight with sphagnum moss, and I worry it will lead to root rot if it’s not repotted soon. Water definitely is not draining easily from the pot, it just gets sucked into the medium like a sponge.
However, I understand that dendrobiums are sensitive to repotting and it should only be done when new shoots are sprouting. The plant is currently in full bloom. What would you suggest in this situation?
A. The roots look fine, and I'm guessing you can pick up the plant by the cane with no wobble in the pot, so the roots are nicely established. If water doesn't drain easily from the pot, the sphagnum is probably packed tight and perhaps is getting older, so just be careful with watering until it is time to repot. I would let it bloom out and then wait til you see the beginnings of new roots, and then put it into your mix of choice. you could pull it out of the plastic pot now and just drop it into a slightly larger clay pot too, until it is time to do the real repotting. (Nov-18)
Growth at Medium Level
Q. I can't identify this strange growth at the growing medium level. I have been growing orchids for several years, but this has me stumped.
A. That looks like a mushroom growing on some decaying bark, and the orange spores are sitting on top of the media. I suspect it is time to put that cattleya in some fresh mix! (Nov-18)
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.
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.
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!
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.
Upside Down Flower
Q. I have a lovely C. lueddemanniana x B Aristocrat in bloom. A large fragrant beauty. But it’s upside down! I did not move it and it did not need staking. Do you know why?
A. I suspect the problem lies with the digbyana in the plant's background. It tends to have a very long pedicel, that attaches a single flower to the main stem of the inflorescence. When the flower is in the bud stage, the lip is the uppermost petal. In most orchids, as the flower opens, the flower twists 180 degrees around its flower stalk to position the lip on the bottom, called resupinate. In your plant, the flower stem was probably unable to support the weight of the flower so it did not twist properly as it was opening. If you remember, stake it next time and perhaps the flower will rotate properly from the nonresupinate to the resupinate position.
Points on Catasetum Leaves
Q. I have a Catasetum saccatum which has developed small ‘points’ on its leaves, I have no idea what caused them.
It has just flowered so the points do not seem to be adversely affecting it.
It was grown with other catasetums, and other orchids, yet it is the only one with the problem.
A. I don't think your catasetum has a disease problem, I think that it has edema, little water blisters than form because the plant can't shed water fast enough through transpiration. It is usually caused by watering late in the day when the night turns cool or watering during gray weather. I have heard of many people having just one of their catasetums form these edema bumps, so there may be some that have a genetic predisposition to edema.
How to Repot This Cattleya
Q. I would like to take this cattleya off the tree fern mount and put it into a basket. It has two new growths and I will try to cut on the red line and not cut the growth off! Do you think this a good plan?
A. I'm not sure you have 3 full leads with those cut lines. What kind of shape is the tree fern in, is it starting to soften in places? I'd start at any soft places and pull the tree fern away from the rest of the tree fern. Then I'd look at the top of the plant and think about what leaves are too ugly or damaged and from the back, start cutting away. Then start thinking about how you might fit the piece or pieces into the basket. Best of luck! If you need help, we're at Ace the first Saturday of the month.
Two leaves on the unifoliate B. digbyana
Q. I recently purchased a couple of Brassavola digbyanas from a central American source, one of them has six pseudobulbs which are unifoliate and one which is bifoliate. Is this common, all my other plant all are unifoliate.
A. Our Go-To-Guy Courtney Hackney answered this one: I have seen that before on B. glauca. It is a somatic mutation that occurs when the cells that would normally make a sheath make a leaf instead. When seeds are treated to increase ploidy or mericloned that often happens on a plant or two. If it just happens once in a while it is not a problem, but it can become the norm and the plant will never flower. If it happens to the next leaf too, the grower needs to cut off those two bulbs and the plant should sprout a new leaf from a bulb that does not have the defect.
Flower Buds Brown and Shrivel
Q. This winter most of my phals, growing outside in Miami, put out new shoots. They looked great and formed buds and then the bud just got brown and shriveled before they bloomed. This happened with most but not all my phals. My vandas recently put out a shoot and similar to what happened with phals, it browned, shriveled and never flowered.
A. I think the thrips got to your buds and sucked the life out of them. Thrips are really insidious, they fly so they can escape your attempts to control them, they burrow into flowers so they're beyond your reach, they have various life forms and might be pupating in your soil, and they are attracted to many plants that might be in your landscape like citrus and gardenias. There are different things you can do. One of the most effective is a weekly or twice a week spraying of all buds and flowers using a pump up sprayer with chemicals like Orthene or Avid. You can also try periodic drenches with Orthene. Scroll down to the discussion of thrips
for some more ideas.
Keikis on Vanda
Q. This vanda has two keikis. What should I do next?
A. I wouldn't do anything except let it grow and flower. You'll have more flowers per square foot of growing area if you let the keikis rock and roll on the mother plant.
New Growth on Cattleya Falling Over
Q. This newly purchased Bc. Fladosa has 2 brown shoots, two new shoots and two good shoots. In the four days since this photo was taken, the green shoot has fallen over. Any ideas?
A. That looks like black rot, it looks like it might have infected all the growths except possibly the two new leads, and it looks like it moved up from the rhizome into the pseudobulb and then the leaf. It's very fast moving, so if there's a chance to save the plant, you have to act now. Pull the plant out of the pot and start by cutting off the back three bulbs.
Then look and feel what is left. If the growth behind the new lead is browning and feels soft, you might as well discard the plant because you won't be able to save it. If it's still hard and green, first pour hydrogen peroxide over everything and then set it in an empty clay pot. Keep it dry, but you can mist daily until you see new root growth. One of the heavy duty fungicides like Subdue, Aliette or Banrot would also help.
Our hot humid summers are a boon to the water molds that cause black rot.
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!
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.
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 on-line.
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.
Orchid Needs Repotting
Q. This plant has not been repotted in years. It blooms all season, but never more than 5-6 at a time. I am content with it but was wondering if I should thin out roots.
A. Never thin live roots. The central part of your plant has probably disappeared because the organic matter in the mix has turned to mush and rotted the roots. You may have to tackle a repot, get the roots wet and pliable, yank it out of the plastic pot and drop it into a large basket.
Bacterial Brown Spot on Cattleya
Q. What’s going on with this fella? It made it all the through the winter then bam!
A. The discoloration on the oldest leaf looks like bacterial brown spot, so it is probably an air movement issue. Looking at the next two younger leaves, it looks like the tips were cut off, possibly because they too had the bacterial spotting. Consider cutting the oldest leaf off about an inch down beyond the yellow discoloration and think about repotting it. Bring it to the next Ace potting clinic and we'll help you with it.
Mites on Catasetum
Q. I have 60 catasetums growing in a screened room. I struggled to keep the mites under control last year so I am being aggressive this time around, but the first two catasetums that emerged from rest are already attacked. The other 12 that are already growing fast and being watered so no mite problems on them. I do not dare treat catasetums with emerging bulbs, so I have to wait until I start watering them. It frustrates me because it is indeed a lot of damage for a plant that just woke up. On top of that I sprayed Sultan on all of them when they went dormant because I am never sure if mites sleep in the root zone while the foliage is gone.
A. How interesting. I just reread Johnson's article about mites
, and he says the mites can live in the media. So perhaps what you really need is a drench instead of a spray. You can try the Bayer 3 in 1 if it has fluvinate in it. Kontos can be used as a drench, it is both xylem and phloem mobile, but it's pretty expensive and not recommended for use on orchids. Johnson recommends Avid, says it is the least toxic. Talstar or Bifen with the active ingredient bifenthrin is affordable and may be your best bet. It comes in a granular form (I use it for fire ants but the active ingredient is effective on mites), and as a liquid.
Is This Black Rot?
Q. Ugh, another one today. The stem gets very dark and bends. This one feels dry and dead at the bend but others have been mushy. I’d like to save it. If you have no other ideas I will unpot, treat with Banrot and mount.
A. What you have is black and it is rot, but it is not the dreaded black rot caused by the water molds Pythias and Photography. You have a situation where the papery sheath around the pseudobulb was pocketing water and the water sitting in this pocket was invaded by the bacteria omnipresent in the environment that attacked the tissue and rotted it. When you have that tissue pocketing, it is a recipe for disaster, so you have to watch and peel it down so it cannot hold water. Then, the problem never arises. Alternatively, you could pour hydrogen peroxide in all these little water pockets, but it's a lot easier to just peel that tissue down so water cannot pocket.
Water Soaked Leaves
Q. My friend sent me a picture of a phal that looks water logged. It currently has buds on it, but she said the leaves were soggy.
A. Your friend's phal is probably history. It looks like it has the fast moving bacterial soft rot caused by Erwinia and it looks like it has infected the entire plant. Even with the blooms, she should discard it to make sure the bacteria doesn't spread to other plants. (May-18)
Yellow Cattleya Leaf
Q. I bought this L. tenebrosa a couple weeks ago. The seller told me the yellow leaf on the old pseudobulb was just from being exposed to more light and it would “green up“ if I put it in less light. It has not. Mostly I would just like to rule out a disease. The newer pseudobulbs look pretty good.
A. I hope you misunderstood the vendor. If the issue was too much light, all the leaves would have had that yellowish cast and of course it is only the oldest growth that has the yellowing leaf. I suspect your plant was not fed enough magnesium and is robbing the older leaf of magnesium to supply the new growth. The yellow leaf will ultimately die and drop off. Our water tends to be very magnesium deficient, so add Epsom salts when you fertilize at the same rate that you are applying the fertilizer. (May-18)
Sunken Spots on Dendrobium Leaf
Q. I'm a long time member of the Memphis Orchid Society, and I noticed this problem when the orchid was returned to me from our society exhibit at the St. Louis orchid show just a couple weeks ago.
I already removed the two top leaves from the pseudobulb, that looked exactly like the ones in the attached pictures of my Den. Sherry Abe that was awarded an AM/AOS last year.
A. My first thought is cold damage. I looked up your dendrobium in OrchidWiz, which indicates its parentage includes the phalaenthe and latouria sections, so it is likely very cold sensitive. Is it possible it was chilled in the trip to and from the show? Was the plant out of your care for more than a weekend? Those types of dendrobiums drop leaves easily if too cold, too dry, etc. from what it is accustomed to.
The good news is the plant is going to be fine, this is just a temporary setback and it will throw off new growths in the coming months.
Black Spot on Phal Stem
Q. Is this black mark on my phal a disease? It seems to be expanding. How should I treat it and will the spike be affected?
A. That phal looks very happy and healthy. The black mark is probably from water pocketing at the leaf base. Pour or spray some fresh hydrogen peroxide on that area of the phal and just keep an eye on it. It is probably bacterial in nature but it doesn't look like a big problem. Peroxide should take care of it and your spikes should continue to grow just fine.
Spot on Cattleya Leaf
Q. What is causing this spotting on my cattleya?
A. That looks like the leaf spotting fungus Cercospora that forms irregular purplish brown blotches on the leaves. A good general purpose fungicide for the leaf spotting fungi is Cleary's 3336 which contains the active ingredient thiophanate methyl. It is sold in smaller, more available quantities as Thiomyl or in combination with another chemical as Banrot. Daconil, that you can get in the local nursery, is also rated very good to excellent for Cercospora. To be cautious, you can remove the leaves with the pentagonal blotching and then spray. I've actually left the leaves on and really didn't notice it spreading, but if you remove the infected tissue, you will remove the spores that spread the fungus.
Brown Spots on Phal Roots
Q. I have been using the "weakly, weekly" fertilizing routine with an MSU formula and flush the pots every 4th week. However, I have noticed that the aerial roots sometimes develop brownish spots which are rather unsightly, but also worries me that they are getting fertilizer burn. Is there a way to prevent this from happening?
A. I'm assuming you don't have a water softener, so you don't have to worry that the sodium from the softener is negatively affecting your orchids. I don't like the brown markings on the roots, put a little sphagnum moss over them to help keep them moist and prevent salts from precipitating.
Lower Leaves Wilting on Rhynchostylis
Q. This Rhynchostylis arrived about a month ago and I grow it in a southwest window. The lower leaves are wilting (they had the black areas when I bought it). I water it everyday and once a week I fertilize it with 1/4 strength MSU. What is wrong and what can I do?
A. My guess would be the indoor humidity does not match the greenhouse humidity in which it was likely raised, and the dehydration and yellowing of the lower leaves is the result. If you have access to live spanish moss, you could drape it around the roots to help raise the local humidity. Growing vandaceous orchids indoors can be a challenge with the low humidity indoors from artificial heating and cooling systems.
Progressive Rot on Pseudobulbs
Q. This Laelia rubescens has a disease. I suspect Phytophthora or virus.
A. Your plants don't look virused. The Laelia rubescens could have black rot, if the rot is moving quickly and is soft and has a distinct nasty odor. If it is more hard than soft and progresses very slowly from older to younger sections of the plant, it is more likely to be Rhizoctonia. Knock it out of the pot and look at the roots, if the oldest pseudobulbs have no roots, it's Rhizoctonia solani that has built up to toxic levels in the pot and caused the root rot. You'll have to cut the plant up until you find healthy tissue, using a sterile tool for each cut, and then pot up in fresh potting media. It should recover, you can pour a systemic fungicide effective on Rhizoctonia through the pot if you have some, and maybe some root stimulator like seaweed to get it growing again.
Orchids Left Out in the Cold
Q. I left these outside during the cold wet weather. Yikes! They're inside now, what do I do?
A. The phalaenopsis may be a goner. Whether the damage is from the freezing temperatures or dripping cold water, the cells have collapsed and been invaded by bacteria. You can remove the leaves, spray the entire plant with hydrogen peroxide or one of the copper fungicides/bactericides. Put it in a warm place and then you wait, perhaps a basal keiki will form.
The other orchid, a Grammatophyllum perhaps, also has some extreme cold damage. Remove those leaves that are totally or mostly brown. If you choose to keep some of the greenish leaves, spray them with peroxide and watch the leaves. If the discolored areas continue to enlarge, remove them. There is a lot of energy stored in those pseudobulbs, so your hope is that they will sprout new healthy growths in the spring.
Dendrobium Leaves Yellowed
Q. I have had this phal type dendrobium for several years. The plant is in a southeast window with some phals (house temp about 65 F, about 60 miles north of NYC). It hasn't produced many spikes over the years but it has 6 canes that had, until a couple of days ago, green leaves and was looking pretty happy. Is the leaf yellowing a bad thing?
A. The phalaenthe dendrobiums are very cold sensitive. I am guessing it was too close to the window on a cold night.
The good news is that dendrobiums are tough. As long as the canes are hard, they'll probably come back. Feel the canes from the base to the top looking for any soft or dessicated spots.
It looks like the canes are a little deep in the pot, why don't you try picking some of the bark out of the top of the pot until you can see the rhizome, then feel the cane at the very base to make sure there is no rot. If nice and hard, find the brightest spot you can in the house and just wait and watch, cut back on watering to say half your normal rate until you see some new growth.
Psychopsis Leaf Yellowing from Base
Q. Just noticed the base of leaves of this Psychopsis are turning yellow. Do you think the two nights below 60 caused this?
A. I don't think it's the cold weather; those Psychopsis oncidiums can be very temperamental.
I think it is a form of rot that comes up from the roots through the pseudobulb to the leaves, possibly rhizoctonia cause it isn't fast like black rot.
When that yellowing occurs, that part of the plant is probably toast. Move the organic matter away from the pseudobulbs and from above the rhizome.
See if there are any roots attached to the oldest pseudobulbs and whether the bulbs are hard or soft. If the roots are gone, the bulbs softening, cut them away and then decide whether you should repot, which could hasten the end, or let the plant try to recover, in which case give it a Banrot drench.
I've lost beautiful psychopsis that went from having 6 consecutive flower spikes blooming like mad to exhibiting this slow moving rot where one leaf after another drops. I've had some suggest it's salt accumulation, though I've rarely found a high salt content in the coarse mix. I keep mine in a somewhat shadier spot than the cattleyas in a mostly inorganic mix. Just leave them alone, let them grow out of the pot and don't disturb the roots, sometimes a leaf yellows and drops and as long as the bulb is hard, just let it do its thing.
Enlarging Rings on Orchid Leaves
Q. I have these rings on a Gongora, as well as two other orchids.
It starts with one leaf, I cut it off and later on, other leaves develop the same problem.
I thought it might be the sun at first but I remember reading that circular patterns are a sign of virus.
Should I trash these 3 orchids fast?
A. I don't think that's a virus, it looks like classic Anthracnose, that is caused by one of the leaf spotting fungi. You should be able to see tiny little dots in the discolored area, those are the spores that spread the disease. You can remove the diseased leaves to a closed container. Fungicides can be sprayed to help prevent spores from settling on leaves and spreading the infection. More air movement and less leaf wetness will help prevent the conditions that favor the disease.
White Crystalline Material on Potting Media
Q. What is this white stuff all over my lava rock? I am repotting cause so many roots were growing out of the pot on my oncidium.
A. Quite a mystery! It's not snow mold. That grows on organic media, and this substance is crystalline. You might think salts precipitated out of the water, but then why are the roots so healthy,with none of them burned? Courtney says there are some bacteria that make colonies and use dissolved minerals as an energy source. The white material, possibly calcium carbonate, dissolved when dropped overnight in a solution similar to vinegar. It doesn't seem to impact the health of the plant. Just another of life's little mysteries!
Oozing Spot on Phalaenopsis
Q. Someone just gave me this orchid and I can’t identify its problem. Can you help identify it and give me some treatment options?
A. The bottom leaf has soft rot, that leaf should be removed immediately. If the rot travels to the crown it will kill the plant. The upper and lower surfaces of the other leaf looks comprised as well. If the plant has enough other leaves to sustain it, you might consider removing that leaf too. Then get a fresh bottle of hydrogen peroxide, or better yet one of those spray bottles of peroxide that Walgreens sells, and spray all the above ground portions of the plant, particularly around the crown where the rotting leaf was. If you were just given the orchid, then you don't really know what happened to it before that allowed the rot to get to the plant. You'll just have to keep an eye on it to see if you stopped the rot in time. If you're a cinnamon person, you could dust the crown of the plant and around the cut edges after the peroxide dries. The cinnamon will dessicate that portion of the plant and create a barrier so bacteria can't invade.