Cattleya rot

[monocotman]

I’ve probably lost about six plants over the course of this year to this form of rot. It’s fairly slow to develop but eventually kills the plant. It usually starts on a new growth, often as the bulb is developing. We are fairly low on chemicals In the UK compared to others. Anybody hazard a guess as to a cure? All I can do at present is cut the plant rhizome as soon as I see it but it rarely stops it. The rot seems to have travelled through the plant before symptoms develop.

David

 

[SouthPark]

MM - does the growing area get some nice air-movement all or most of the time? Hard to say right now what it's due to. Usually nice temperature growing range, and nice lighting levels and nice lighting duration, and no relatively fast/abrupt change in temperature (increase or decrease) between two significantly different temperatures, and good air-movement (around leaves and around stems and through the growing media and around the roots), and adequate nutrient and elements, and no drowning of roots --------- should result in nice healthy catts. Are the roots down in the dark depths of the pot all ok?

If the roots are all good inside the pot (ie. not rotting), then could also consider mag and/or cal deficiency. Definitely not suggesting it's any of these things behind it. Just considering only.

You mention low on chemicals there. Assuming not a nutrient or element deficiency, and no root rot, and no attack from organisms (such as snails eating roots etc) ..... then maybe could try copper spray for orchids, or even monterey garden-phos, or thiomyl.

 

[monocotman]

So do you think that this is more of a cultural issue than a disease?
The problems have all happened with plants that grow on one of the five windowsills in the house. None of the others are affected. All the plants grow in very similar conditions and are watered and fed on the same schedule,
david

 

[SouthPark]

So do you think that this is more of a cultural issue than a disease?
The problems have all happened with plants that grow on one of the five windowsills in the house. None of the others are affected. All the plants grow in very similar conditions and are watered and fed on the same schedule,
david

Possibly David. Possibly a growing condition issue. I was mainly focusing on "I’ve probably lost about six plants over the course of this year". I assume it's due to similar symptoms. Considering each condition I mentioned in the previous post could maybe help with tracing possible causes. The leaves of that particular plant are looking quite pale there too. Getting on the yellow side, which is not necessarily bad, as some of my catts in very bright light conditions have fairly yellow leaves too.

If the roots are ok, then maybe could consider mag/cal deficiency. But certainly not meaning it necessarily is ----- as it may be getting enough mag/cal already. Will be really nice to trace the cause here. Totally understanding of the situation and the need to find out what's going on with that one. Maybe check the roots David if not yet checked - just in case.

Also inspect the medium down in the dark depths of the pot ---- such as -- see if there's any signs of soggyness/saturation in any region in the pot that might just hang there for relatively long periods of time, possibly allowing for unwanted organisms to grow in there, or stationary/still water in some parts of the media drowning and rotting roots, leading to other effects - weakening the plant, bacteria etc.

Also, even though most probably unrelated ---- check this out too ------ at this link here (click on download full-pdf when you get there), and check out PDF page 15 (which is page 21 of the magazine). Unrelated, but nice info too!

 

[Paphman910]

Your plant looks a bit yellow on the older leaves. Is it possible that your plant got sunburn on the new growths and then rot sets in during the cooler weather?

 

[abax]

One thing I'd definitely do is cut that growth cleanly off and apply either Dragon's Blood or hydrogen peroxide or
some people use cinnamon. Repot quickly and out of plastic into clay with drainage holes.

 

[SouthPark]

Also ----- check that dark patch too --- to see what that is. And see if the temperature next to the window sill gets very cold at any times (eg. night time or other times) ---- also including the temperature inside the pot ---- roots temperature. See if it ever stays relatively cold and wet in the pot for long times.

 

[Tlynnt66]

I use either 50/50 peroxide and distilled water or a 5% mixture of alcohol and distilled water. You can use cinnamon, but if there is any damage to the roots, then the strong nature of the cinnamon can burn them a bit, which makes it harder to heal. If you do use the cinnamon, I would suggest rinsing it out thoroughly after a day or two.
I've had cattleyas do this to me, and it's super hard to get them to come out of it, but allowing the roots to dry out fairly well for a couple days before rehydrating the mix seems to help my cases. Good luck to you!!

 

[DrLeslieEe]

Sad to see this.... looks like black rot of sorts...

Few questions:

1. what kind of cattleyas succumbed to this? Species or hybrids?
2. what is your feeding routine?
3. is there constant air around plants 24-7?
4. do pots sit in trays with others or individual trays?
5. do you spray early or late in day? Does water sit on leaves overnight?
6. what treatment routine have you tried with the other plants with no success? Have they all been isolated from healthy plants and still skips to others?
7. is there a cold draught or heater around plants?
8. what light do they get to get so yellow leaves?
9. what is your growing media?
10. does this rot occurs in surrounding plants (esp other generas)?

I know you grow great Cattleyas and doing many things right. If we can analyze the conditions that weakens a plant to this disease, you can prevent it happening to the others.

 

[Ozpaph]

bad rot. Cut, cut, cut. Less water. More air.

 

[monocotman]

Thanks for all the suggestions.
I‘ll answer Dr leslie’s questions.
1. a combination of both species and hybrids.
2. at every watering, little and often. I use rain water and rain mix with a TDS of about 170, same as the phrags.
3. there is no forced air movement on any of my plants, phrags or catts at any time. They live on windowsills in the house. There will be natural air movement in front of the windows especially when the sun is out.
4. Most of the pots do sit in trays with others. This maybe a source of transfer of rot. I sterilised the trays with bleach after it happened. In the bottom of each tray is Leca or grow stones that act to keep the pots off the bottom of the tray and there will be a bit of a water reservoir in each which helps with humidity.
5. I spray a bit of water early in the day onto the compost surface to help with rooting of the new growths. Nothing else.
6. I isolate the plants and cut the rhizomes to try to stop the rot. it is rarely successful.
7. Many of the trays sit on windowsills with a radiator underneath them. I deflect the direct heat from the radiators with a sheet of silver foil which sits on top of the radiators. Not ideal but it’s the best that I can do.
8. This plant has gone yellow in the last month due to the rot. Before that it was the picture of health.
9. 100% orchiata, except where I have yet to repot a plant bought from a vendor.
10. I don’t have other generas. The catts grow with just catts.

I am leaning towards a cultural issue. One plant I lost was quite definitely due to it being too wet. It was a small pot wedged between some larger ones and I did not realise that the water reservoir on the tray was high enough to keep it too wet.
The first plant to go was a nice plant of percivalliana ‘summit’ that when repotted had dodgy roots. It looked like they had been eaten a bit. It was repotted at the right time, the two new growths had new root nubbings showing but maybe by that time it was too late and the rot was already there.
Another is a mature plant of laelia purpurata carena. Two years ago it produced a nice large growth that rotted when the bulb was expanding. I cut it off as soon as it was visible and the plant appeared ok. This year it produced another new growth but this time the same thing happened. As the new shoot was developing a bulb it rotted. This time I have lost the new growth and now the bulb behind it and the plant is in sick bay.
The plant in the photo is a cattleya labiata semi alba seedling. The only reason I can think that it has suffered is that it is growing in a tray where there was a previous problem with rot. Everything has now been sterilised but it may be too late for this plant.
You have to remember that I have about 70 catts and most are doing very well. I’ve been very good this year during lockdown at repotting them at the correct time, when new roots are appearing from the new shoot. It has to be said that the problems have tended to occur in plants that have not been repotted. As my culture has improved with catts I am repotting more often and hopefully the root growth will also improve.
Its likely that a combination of not repotting as often as maybe I should and growing in trays with a water reservoir has allowed rot to gain a foothold in the collection.

 

[TropiCool]

I had what looks to be a similar problem with a Cattleya Loddiaca (C. loddigesii x C. aurantiaca) that I've grown on an apple wood mount for over 7 years, living with me in Ireland, then Spain and now the Netherlands. It was a very dependable grower and bloomer. Last summer it went outdoors and appeared to be thriving for a couple of months, sending up a new growth, a sheath, and then as the buds were about to emerge the entire growth went black and collapsed in a few days. Since then it's cast the remaining leaves and I've cut off several growths that were going smooshy-brown and have what's left in an ICU under lights.

It seemed to go systemic rapidly. After cutting away the infected pseudobulbs I soaked it in cinnamon water, followed by dousing with a systemic fungicide from the garden center. Now I'm just waiting to see what happens next.

My other Catts seem OK, most are also on mounts, indoors now for the Dutch winter, in both East and West facing windows.

I'll keep an eye on this thread in case anything more close to my own experience crops up.

 

[Teresa Koncolor]

You may need to add more calcium during the growth phase.
Also, I've had good results on root growth with added seaweed extract.
I've had black rot after heavy rains. I've treated with Banrot and Subdue. It looks very different from what you have in the pics

 

[PeteM]

https://staugorchidsociety.org/PDF/OrchidPestsandDiseasesbySueBottom.pdf

IMO. I would keep them isolated away form other cattleyas, treat it as if it is black rot. Anything you use on them, pots, trays, clay balls, never use these again on the rest of the collection unless you can sterilize it in the oven or burn it cherry red with a torch. Looks like they might need more air in the pot, I would repot, after cutting off the areas, spray with the bare plant and roots with a fungicide and repot in an open mix, or pot with more air, aircone pot, basket, net pot. Tricky to do this when the plant is not growing. 'growing in trays with a water reservoir has allowed rot to gain a foothold'. This definitely promotes an environment for this to occur. I think you right and are on the correct path.

 

[monocotman]

Thanks again for the comments. I think I will add some more calcium to the feed, especially in summer when things are growing fast. It’s easy enough to to do as the tap water here is hard.
I‘ve isolated the affected plants and if they die everything will go in the bin.
The only decision to make with two of them is whether to repot them, but it is the ‘wrong‘ time and neither is producing new roots. I am inclined to do it anyway and see what happens. Both have several mature pseudobulbs.

 

[southernbelle]

Thanks for all the suggestions.
I‘ll answer Dr leslie’s questions.
1. a combination of both species and hybrids.
2. at every watering, little and often. I use rain water and rain mix with a TDS of about 170, same as the phrags.
3. there is no forced air movement on any of my plants, phrags or catts at any time. They live on windowsills in the house. There will be natural air movement in front of the windows especially when the sun is out.
4. Most of the pots do sit in trays with others. This maybe a source of transfer of rot. I sterilised the trays with bleach after it happened. In the bottom of each tray is Leca or grow stones that act to keep the pots off the bottom of the tray and there will be a bit of a water reservoir in each which helps with humidity.
5. I spray a bit of water early in the day onto the compost surface to help with rooting of the new growths. Nothing else.
6. I isolate the plants and cut the rhizomes to try to stop the rot. it is rarely successful.
7. Many of the trays sit on windowsills with a radiator underneath them. I deflect the direct heat from the radiators with a sheet of silver foil which sits on top of the radiators. Not ideal but it’s the best that I can do.
8. This plant has gone yellow in the last month due to the rot. Before that it was the picture of health.
9. 100% orchiata, except where I have yet to repot a plant bought from a vendor.
10. I don’t have other generas. The catts grow with just catts.

I am leaning towards a cultural issue. One plant I lost was quite definitely due to it being too wet. It was a small pot wedged between some larger ones and I did not realise that the water reservoir on the tray was high enough to keep it too wet.
The first plant to go was a nice plant of percivalliana ‘summit’ that when repotted had dodgy roots. It looked like they had been eaten a bit. It was repotted at the right time, the two new growths had new root nubbings showing but maybe by that time it was too late and the rot was already there.
Another is a mature plant of laelia purpurata carena. Two years ago it produced a nice large growth that rotted when the bulb was expanding. I cut it off as soon as it was visible and the plant appeared ok. This year it produced another new growth but this time the same thing happened. As the new shoot was developing a bulb it rotted. This time I have lost the new growth and now the bulb behind it and the plant is in sick bay.
The plant in the photo is a cattleya labiata semi alba seedling. The only reason I can think that it has suffered is that it is growing in a tray where there was a previous problem with rot. Everything has now been sterilised but it may be too late for this plant.
You have to remember that I have about 70 catts and most are doing very well. I’ve been very good this year during lockdown at repotting them at the correct time, when new roots are appearing from the new shoot. It has to be said that the problems have tended to occur in plants that have not been repotted. As my culture has improved with catts I am repotting more often and hopefully the root growth will also improve.
Its likely that a combination of not repotting as often as maybe I should and growing in trays with a water reservoir has allowed rot to gain a foothold in the collection.

One thing you mention is 100% Orchiata for your mix. Keith Davis, a premier cattleya grower here in the US, has worked with the Univ of North Carolina testing the acidity of Orchiata over time. Straight Orchiata turns very acidic, very fast after a couple of years. Apparently the dolomite coating added as a buffering agent washes off over time and at about a year the pH starts to drop. Not such a problem with Orchiata in a mix, but straight. I use it with perlite/charcoal and repot after a max of 2 years, so don’t have problems. He no longer uses Orchiata for that reason. It’s not likely what’s causing your disease? problem as it would not likely be confined to one windowsill, however you mention not having been as good in the past about repotting. If you contact him I’m sure he will give you a link to the study UNC did. If you send him a photo of your plant he might even have some ideas about cause. Nice guy.
www.keithdavisorchids.com

 

[SouthPark]

I use 100% scoria for my catts (and paphs and phrags and sarco and spathoglottis, vanda, encyclia, oncid, sedirea, dend and angraecum and a phal) in the tropics. I don't ever repot unless the plant runs out of room. And although I don't have as many orchids as a lot of growers ----- I haven't encountered bulb rot for a few decades of growing orchids. I haven't even had an orchid die over this time or run into bulb/root issues - except for a spider-mite related leaf rot on a baby paph, which was eventually cured with copper spray (stopped the rots right in its tracks).

And I only apply fertiliser (relatively weak fertilise) once a month. And also I do the weak mag-cal once a month. First day of the month, I do the weak fertilising. Then 2 weeks into the month ---- the mag-cal. All the rest of the time is just using a garden pump sprayer with nozzle to water the orchids.

I grow the bulk of orchids under a balcony --- so semi outdoors growing. The leaves and stems never get wet, unless strong wind and rain just happens to blow water onto the plants during very strong rainy season. I do have some time on my hands sometimes --------- and I generally apply the bulk of the water around the outside ..... the outskirts of the pot. So I choose a pot that is big enough, and the bulk of the water goes into the media at the outskirts. Much much less ----- or occasionally none - is added toward the centre. So think of airyness and also think of dry-wet gradients, and also think of humidity for the roots, and also think of making things hard for unwanted activity growing inside the pot. Sometimes - people might say a dry out of the media inside the pot is good for the roots ------ but might not also consider that a dry out can make things tough for unwanted organisms in there.

Each grower has their own procedures for doing various things. As long as they come up with a method that keeps the orchids growing nicely (all of them) for very long periods of time (decades, indefinitely) and doing what we can to cut down on chances of disease growing and disease spreading, then that is great ---- and that's the aim. There are always exceptions - where some people grow orchids with their roots in water, and some orchids with root in wet leca plus water reservoir, and may have no problems with their orchids for decades as well. As long as we run through the checklist on what can harm orchids in general (when growing them) ---- such as root drowning, unwanted stuff growing, not enough nutrient or elements into the orchid, not enough water, temperature range and light range and duration, air-movement around leaves and stem and through media, not allowing temperature of the plant or portions of the plant to change very quickly or abruptly etc ..... then we can cut down on problems a lot.

If 1 or more of those things is/are overlooked, then we need to do something to not overlook it.

For sure - there are considerations to be made about media accumulating salts. So if the watering schedule involves continual bombardment of the media with fertiliser, then that needs to be taken into account. So I can understand the need for some people repotting every once in a while. And I also understand that some areas and regions have insects and snail and other attacking animals that need to be considered. But assuming that kind of thing is all under control ------ the important thing is 'the checklist'.

A lot of us here are very experienced or long-time orchid growers. So this is just a friendly sharing and discussion of information. We just pick and filter what we need to make sure our orchids stay healthy in our growing areas.

 

[southernbelle]

I use 100% scoria for my catts (and paphs and phrags and sarco and spathoglottis, vanda, encyclia, oncid, sedirea, dend and angraecum and a phal) in the tropics. I don't ever repot unless the plant runs out of room. And although I don't have as many orchids as a lot of growers ----- I haven't encountered bulb rot for a few decades of growing orchids. I haven't even had an orchid die over this time or run into bulb/root issues - except for a spider-mite related leaf rot on a baby paph, which was eventually cured with copper spray (stopped the rots right in its tracks).

And I only apply fertiliser (relatively weak fertilise) once a month. And also I do the weak mag-cal once a month. First day of the month, I do the weak fertilising. Then 2 weeks into the month ---- the mag-cal. All the rest of the time is just using a garden pump sprayer with nozzle to water the orchids.

I grow the bulk of orchids under a balcony --- so semi outdoors growing. The leaves and stems never get wet, unless strong wind and rain just happens to blow water onto the plants during very strong rainy season. I do have some time on my hands sometimes --------- and I generally apply the bulk of the water around the outside ..... the outskirts of the pot. So I choose a pot that is big enough, and the bulk of the water goes into the media at the outskirts. Much much less ----- or occasionally none - is added toward the centre. So think of airyness and also think of dry-wet gradients, and also think of humidity for the roots, and also think of making things hard for unwanted activity growing inside the pot. Sometimes - people might say a dry out of the media inside the pot is good for the roots ------ but might not also consider that a dry out can make things tough for unwanted organisms in there.

Each grower has their own procedures for doing various things. As long as they come up with a method that keeps the orchids growing nicely (all of them) for very long periods of time (decades, indefinitely) and doing what we can to cut down on chances of disease growing and disease spreading, then that is great ---- and that's the aim. There are always exceptions - where some people grow orchids with their roots in water, and some orchids with root in wet leca plus water reservoir, and may have no problems with their orchids for decades as well. As long as we run through the checklist on what can harm orchids in general (when growing them) ---- such as root drowning, unwanted stuff growing, not enough nutrient or elements into the orchid, not enough water, temperature range and light range and duration, air-movement around leaves and stem and through media, not allowing temperature of the plant or portions of the plant to change very quickly or abruptly etc ..... then we can cut down on problems a lot.

If 1 or more of those things is/are overlooked, then we need to do something to not overlook it.

For sure - there are considerations to be made about media accumulating salts. So if the watering schedule involves continual bombardment of the media with fertiliser, then that needs to be taken into account. So I can understand the need for some people repotting every once in a while. And I also understand that some areas and regions have insects and snail and other attacking animals that need to be considered. But assuming that kind of thing is all under control ------ the important thing is 'the checklist'.

A lot of us here are very experienced or long-time orchid growers. So this is just a friendly sharing and discussion of information. We just pick and filter what we need to make sure our orchids stay healthy in our growing areas.

Perhaps I need to clarify. I only repot when the new bulb(s) are crowded against the edge of the pot or are growing over the edge. But for me, that is 1-2 years.

 

[SouthPark]

Thanks SB for sharing details of your procedure too.

 

[DrLeslieEe]

Based on your answers, and since you grow indoors like me, I can share what my experiences are from growing Cattleyas over the last two decades (in sweat and tears).

I find that cattleyas will grow well in any medium up to 2 years, when the mix starts getting too acidic. The orchiata has a tendency to do this, particularly if flushing is not in your regiment. I agree with SB to include perlite and activated charcoal into the mix (as I do in ratios of 3-2-1). This will keep the pH more adaptable to the roots. Do checked the pH of the outflow as well as the pH of the water/fertilizer trends (ideal range is 5.8-6.2 +/- 1 pH). Sadly, I didn't do this for years and my pH was 4-5 with the fertilizers and I was killing roots (even though I use RO water). My plants went downhill and suffered all ailments (from rot to root loss). Once I remediated the media and pH, all was well and roots grew like crazy.

I cannot stress the (importance) use of a mini fan or room fan to circulate stagnant air around the plants indoors, especially around the heaters and cold windows. The pockets of air can induce mold and microbial growths, holding on to condensation and leaf wetness in areas you may not see. I have seen my plants succumb to new growth black rots (like yours) due to this. It disappeared when I had fans on plants 24-7 with a gentle breeze. Likewise on hot days with the sun blaring down on my west facing window, the plants heat up to almost 90F and can overheat without the fan. These micro niches are more dangerous than most people think and can weaken the plant over time. That's why by the time we see the rot, it has already been there for days and maybe weeks, spreading through plant areas you can't even see. That's why cutting off visible plant tissue is not a cure. And remember that mold is everywhere!!!

Another indoor cultural mistake I made (and seen many people do) was using communal collection trays for several plants. These trays are harbor not only wastes but bacteria, viruses and molds, most are harmless to healthy plants. But if a root of another plant has been damaged by pH or other physical method (such as during bloom staking), it can enter and infect. This infection is usually staved off by healthy plants, but a continuing stressed plant from, let's say, the above items, they can succumb to it. I have seen an entire tray of 8 adult cattleyas killed by rot in a matter of 2-3 months, while the next tray had no effects. What I do now is to have each cattleya plant on the shelf with their own shallow plastic trays. This helps keep other plants' waste water from them as well as to allow longer water absorption (dries in 2 days).

Part of my feeding routine is to use supplements that can improve the immune function of the plants. These include rotations of kelp, aspirin, beneficial bacteria (Sub. futilis), mycorrhizae, Hygrozyme and B1. These do not replace the feeding of complete fertilizers and minerals, but rather act as vitamins.

If I do find rot or disease in my collection, here is my system:

1. immediately isolate plant
2. cut off affected tissue
3. treat with peroxide, physan and/or phyton27 copper (also spray areas and plants in close proximity)
4. dry plant in pot for 2-3 days
5. then gently remove partial media to see roots. If alive, put fresh media. If dead roots, remove and cut off, repot in NZ spagnum moss, cover in plastic, set in warm area)
6. retreat plant every week

The success rate of this is less that 50% because as mentioned before, the disease part of what you see is just the tip of the iceberg.

Anyways, my 2 cents (or pennies as you say in UK) lol...