# Cattleya rot



## monocotman (Oct 27, 2020)

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


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## SouthPark (Oct 27, 2020)

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.


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## monocotman (Oct 27, 2020)

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


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## SouthPark (Oct 27, 2020)

monocotman said:


> 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!


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## Paphman910 (Oct 27, 2020)

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?


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## abax (Oct 27, 2020)

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.


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## SouthPark (Oct 28, 2020)

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.


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## Tlynnt66 (Oct 28, 2020)

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!!


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## DrLeslieEe (Oct 28, 2020)

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.


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## Ozpaph (Oct 28, 2020)

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


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## monocotman (Oct 28, 2020)

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.


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## TropiCool (Oct 28, 2020)

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.


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## Teresa Koncolor (Oct 28, 2020)

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


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## PeteM (Oct 28, 2020)

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.


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## monocotman (Oct 28, 2020)

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.


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## southernbelle (Oct 28, 2020)

monocotman said:


> 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.
> ...


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


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## SouthPark (Oct 28, 2020)

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.


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## southernbelle (Oct 28, 2020)

SouthPark said:


> 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.
> 
> ...


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.


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## SouthPark (Oct 28, 2020)

Thanks SB for sharing details of your procedure too.


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## DrLeslieEe (Oct 29, 2020)

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...


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## Ozpaph (Oct 29, 2020)

great points Leslie


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## monocotman (Oct 29, 2020)

Leslie,
many thanks for this. I think you’ve covered everything. I will definitely have a rethink of my growing areas.
David


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## Ray (Oct 29, 2020)

I think that’s more likely a pathogen than a cultural issue, but we do have to keep in mind that poor culture (thinking about the possibility of changes in the media) can make plants more susceptible to pathogens.

I doubt it’s a calcium issue, as a deficiency typically affects newly-growing tissues, not existing, already-grown stuff.

If the potting medium question has been eliminated, I’d start by treating with a copper-based systemic.


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## SouthPark (Oct 29, 2020)

monocotman said:


> repotting them at the correct time, when new roots are appearing from the new shoot.



MM ----- I reckon the general rule-of-thumb that people pass around ---- about repotting when new roots are appearing .... is just a rule-of-thumb. I repot any catt and pretty much any of my tropical orchids at any time, and nothing bad will happen to them. Some people mention bifoliate catts - in particular bifoliate species catts - really need to be repotted when roots are sprouting etc. I don't think that's correct either. I'll repot any regular sort of catt --- species or hybrid - bifoliate or unifoliate. Any time.

The rule-of-thumb probably doesn't strictly equate to 'the correct time' for repotting. I believe it just depends on how the orchid is grown and cared for there-after (- after a potting/repotting that is).

My remarks definitely don't mean to tell people that they themselves can repot at any time. The rule-of-thumb probably helps some or many growers (avoid orchid issues) in one way or another.


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## alex.sorensen51 (Oct 29, 2020)

I agree,with the problem being cultural. The pre-amble is ,I was one of the first to create a database of cultural care for a 2000 plant collection,way back when computers used dot matrix printers and rolls of paper.What I found was ,when orchids don't get re-potted on time,they develop all kinds of contagion based on media breaking down,and not allowing air around the "roots", thus creating the perfect storm for virus',fungi,and mineral build-up. In your situation,I had a very similar problem,and it turned out to be fusarium wilt,with the characteristic purple veination in the stem and lower basal area,and "root" die-off.If you have species plants...immediately de-pot,sterilize,and repot using lots of styrofoam with bark.You may be able to have it grow out of the problem,if you use much more frequent re-potting cycles.


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## SouthPark (Oct 29, 2020)

This is also where the idea of occasional media dry-out ------ how occasional .... not sure, but just sometimes ........ could possibly help to deal with certain unwanted activity (growth or build-up of things) inside the pot and in the media and on roots etc. This is aside from the other benefit of sometimes giving the roots a little bit of a breather from a dry out.

It is true that some orchids adapted to some conditons are exceptions. So there will always be exceptions to cases. But totally agree ------ if we purposely do things to make things hard for certain unwanted organisms from doing their unwanted activities, then that is a good thing.


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## monocotman (Oct 30, 2020)

So here is where we are now. I’ve just ordered 80 litres of orchiata from my regular supplier. The plan from now on is to repot strictly on a 2 year basis.
In fairness since Covid hit I have been repotting many of the catts at the appropriate time. I have got through a 40 litre bag of orchiata this summer which is about a third of the collection.
The communal collection trays will have to stay, they are too convenient plus they shade the mostly black pots from the direct sun but what I can do is to take the pots out of them to water. As there is LECA in the bottom To keep the pots off the floor, there should then be no cross contamination of pots with water.
The issue of moving air is more problematic. I take your point Lesley about fans, but in a domestic setting, they are very awkward. I am careful with the south facing windows especially, to open the top small windows when there is any chance of heat stress and sunburn. This stops all but the very occasional problem with scorch.
The leaves are never wet so there is very little chance of problems here, the only issues I have with the leaves is scale, with which I have a running battle. I am now on top of it but you need to be eternally vigilant and it means I need to inspect all plants every couple of weeks at least, which isn’t a bad thing.
I am interested in your comments about watering and it being ok in your conditions for the plants to sit in a bit of water as long as it dries out with a couple of days. I have noticed that a couple of my catts that were wettter than normal grew bigger pseudobulbs and this suggest that maybe I am under watering some of mine, but it’s a fine line to tread when I am not keeping an airflow over them and they could sit wet for too long and clause all the issues we have been speaking of.
I am going to try this next year in summer by keeping the plants that are in active growth slightly wetter than the others, by reducing the time between watering.
Anyway, a huge thank you to everyone who has contributed to this thread, especially Dr Leslie, I have now got to go and put what I’ve learned into practise!
Yay slippertalk!


the photo shows the traysin the south facing windows with the silver foil covering the radiators to deflect the heat away from the leaves.


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## Ray (Oct 30, 2020)

Let’s think about this repotting “rule of thumb”.

As roots grow, the root structure - cell types, shape, size, and number, from the cortex through velamen - is tailored to the environment in which the grow, and once grown, cannot change.

That said, just as new roots are emerging is, without a doubt, the best time to repot, so those new roots will grow to be optimal for the environment.

I think that the factor that makes people differ in their opinion of that being essential versus a general recommendation depends upon potential changes in the root environment. For example, if - using the example above - you use a relatively stable medium and replace it regularly, before it decomposes to a significant degree, the “old” and “new” environments are pretty similar, so the root function is relatively unaffected. In that case, waiting for new roots to emerge isn’t a big deal.

Now jump to someone changing potting media or culture - bark to semi-hydroponics, for example - and there will be a drastic difference between the old and new conditions, so the emergence of new roots is almost essential, as the old ones will not function well in the new environment, putting the plant at risk as the sub-optimal roots fail.

The rate of root failure and necessity of new root emergence is mostly determined by the degree of difference. Between the old and new conditions. I recently move all my phals from sphagnum to rock wool cubes - a walk in the park. If I was moving a cattleya from coarse Orchiata into them, I’d pat far more attention to the timing.

Now then, this doesn’t even take into account the differences between plants or cultural conditions. A plant grown with summer sun, warmth and humidity is likely to carry on more easily that one in winter, cool and more arid conditions.


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## SouthPark (Oct 30, 2020)

monocotman said:


> the only issues I have with the leaves is scale, with which I have a running battle.



If indoors ------ have you tried - just for a test ----- some imidacloprid (or similar)?


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## monocotman (Oct 30, 2020)

Yes it’s what I use for scale. It kills almost all of it, then I just have to be vigilant for any misses,
David


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## DrLeslieEe (Oct 31, 2020)

I switched my cattleyas to semi-water culture (SWC) because they were not rooting into the media and were gettting more dehydrated. I was pretty much desperate as the bulbs were shrinking too much, almost desiccated. Then I saw my orchid buddy grow his catt hybrids in SWC and they were thriving. I thought why not try mine in them. And it worked... for my dry indoor conditions of 35-45% humidity.

The results became evident in a few months. I switched over in fall last year as first experiment and then most in spring and late summer this year.

I saw roots grow into the mix and the bulbs were more plump than usual. The important thing is to let the root dry for a day or two. This method allows the roots to soak in more water over a longer time. As my buddy says ‘they’re thirsty’!

I’m attaching a few pics to show this:






Above, you can see the root grow into the media. And the bulbs plump and leaves not desiccated. These are all species.

The pic below shows what happens if a deep water reservoir is not detected by roots from SWC, and roots everywhere except inside bark.




As you can see, it’s a mess of roots that attached everywhere.

The layers in this SWC pot is bottom inch of clay pebbles (LECA) or large perlite, middle 2-3 inch of orchiata/perlite/charcoal (ration 3:2:1), and top inch layer of NZ moss.

As for air, I attach mini fans on top of the plants on the shelf to keep air movements 24-7. They blow the light heat away from top of leaves as well as introduce fresh cooler air from window and room. See pic below of one of my cattleya shelves.




All the cattleyas have their own plastic trays to trap water. Roots grow in search of this water, so they stay in there! Makes a cleaner looking plant. 

Caveat: this method works for me. Might not for everyone, so watch carefully not to rot roots.


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## SouthPark (Oct 31, 2020)

Excellent description and excellent pics of your setup DLE. I also like the hello kitty shade kit. Very cute hehe


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## DrLeslieEe (Oct 31, 2020)

Hehe I was wondering if anyone would notice.

I decided on those smiling shades to keep my cattleyas think happy thoughts lol


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## Ozpaph (Nov 1, 2020)

I wonder if the deep plastic trays diminish airflow around the pot and root area, facilitating rot. I would try a shallower vessel. Catts grow on trees with lots of air around the roots. An idea to contemplate.


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## SouthPark (Nov 1, 2020)

Ozpaph said:


> I wonder if the deep plastic trays diminish airflow around the pot and root area, facilitating rot. I would try a shallower vessel. Catts grow on trees with lots of air around the roots. An idea to contemplate.



It is true OP. Very true. It probably also depends on whether the roots of a catt are adapted to lower oxygen level environments or wet environments (or not). But in general ----- for regular catt roots, I like the suggestions about air-flow around the roots ----- through the media etc. A shallow pot and airy media will definitely help in that way.

One method I use that works for wide pots (or wide-enough) pots - that can also be deep too ---- is the method of dumping most of the water toward the outskirts of a suitably large size pot. If the bulk of media in the pot (such as the central region - and down in the deep dark depths) is prevented from becoming a wet slush/slurry/sludgy saturated mix --- especially around the bulk of the roots ----- then that will help catts (and other orchids) out ----- by not getting into long-time wet roots condition.

When watering the outskirts of the pot, while having the inner regions dryer (much less wet) ..... it might be possible that (using a pot having good size drainage holes at the bottom) the roots can have nice humid conditions to grow well ----- with a wet/dry gradient inside the pot.

If an orchid grower finds that - when they unpot a catt and see a big mass of soft mushy gray/olive/dark water logged roots ...... then the pot may just not be large/wide enough, or the media not quite airy enough, or the watering strategy/plan isn't suitable. Also knowing that 'very cold plus very wet' isn't good too for roots.

There can be exceptions. For example ----- if an orchid just-so happens to have its roots grow out (naturally reach out) into a very wet medium, then its roots may well somehow 'adapt' to that particular wet or low oxygen environment. So some people expecting to pull out a mass of mushy dead roots can sometimes be 'surprised' when they see a mass of nice green/white wet roots. It can mean the roots 'adapted' to the environment. But roots apparently (we've been told) can handle low-oxygen watery environments up to a point or a limit. So that just means growers be 'warned' about what could happen ..... such as a mass of nice adapted green/white roots could take a dive in health if something doesn't go well - such as bacterial activity/rotting starts up if portions of roots get into trouble due to not enough O2 ----- then one thing leads to another.

So - keeping control of the conditions within the pot and in/around the roots is very important (this is well-known) ---- aside from the conditions in and around the leaves/stem (temperature and temperature changes and rates of temperature changes, air-movement etc).


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## southernbelle (Nov 2, 2020)

SouthPark said:


> It is true OP. Very true. It probably also depends on whether the roots of a catt are adapted to lower oxygen level environments or wet environments (or not). But in general ----- for regular catt roots, I like the suggestions about air-flow around the roots ----- through the media etc. A shallow pot and airy media will definitely help in that way.
> 
> One method I use that works for wide pots (or wide-enough) pots - that can also be deep too ---- is the method of dumping most of the water toward the outskirts of a suitably large size pot. If the bulk of media in the pot (such as the central region - and down in the deep dark depths) is prevented from becoming a wet slush/slurry/sludgy saturated mix --- especially around the bulk of the roots ----- then that will help catts (and other orchids) out ----- by not getting into long-time wet roots condition.
> 
> ...


One thing I do in deep 7” or all 8” - 10” (my largest) pot, is to put a 2” net pot upside down in the center bottom (secured with twist ties) and use a soldering iron to put holes in the center bottom of the pot under the net pot for air to enter. Keith Davis recommended the net pot idea. 
I also use either power+/super mix or all super (both with perlite/charcoal) in 7” or above. Very airy mix and airy center. I still go 7-10 days in summer and 10-12 in winter between watering in biggest pots, with fans and temp/humidity control. But roots usually look good on repot.


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## SouthPark (Nov 2, 2020)

SB - thanks for sharing and explaining the method that you use. I have heard of that very useful method. That one will definitely help cut down on water logging issues.


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## SouthPark (Nov 2, 2020)

SouthPark said:


> It is true that some orchids adapted to some conditons are exceptions. So there will always be exceptions to cases.



I probably have typos elsewhere too. But I meant 'condit*i*ons'. But unfortunately, the window time for edits has lapsed hehe.


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## monocotman (Nov 21, 2020)

This an update in the improvements I’ve been able to make following the recommendations of Dr Leslie and others.

Firstly all the affected plants have either been isolated or thrown away. I lost the labiata alba ‘angerer’ soon after I had posted it to rot. Most annoying.

Next all plants that were not repotted earlier this year have been repotted.

Then any plants that were growing anywhere close to rotted ones have been given the ‘bleach’ treatment. This involves soaking the plants for 10mins in a bucket of water to which has been added 1 tablespoon of household bleach, pot and all the foliage. They are then given 10 mins in a bucket of water without bleach. This is pretty good at killing most things, bugs included and maybe any surviving rot spores.
Lastly they have all be put into their own planters to stop cross contamination when watering.


this is the purpurata room. All growing well.


this is the sitting room where the rot happened. Fingers crossed.
David


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## abax (Nov 21, 2020)

David, I was going to suggest that you switch to slotted clay pots with the Orchiata,
charcoal and perlite, however, since you've already repotted...too late. I do wish
you consider clay pots with holes or slots for your Catts.


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## Ozpaph (Nov 22, 2020)

here's hoping


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## monocotman (Nov 22, 2020)

Angela,

I have grown the odd Catt indoors in clay pots and they did ok. 
The root growth was good and they are definitely more forgiving of any slight overwatering.
It’s something I may try in the future but to source 60 clay pots of the appropriate size would be quite an undertaking,

David


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## eds (Nov 22, 2020)

Especially clay pots with holes or slots in the side - I looked for them and, short of getting them commissioned myself from a pottery, the nearest place I found was in Belgium!


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## abax (Nov 22, 2020)

What you do is buy clay pots and drill holes or slots in them. Ain't hard. If you break one
now and then, you've got pottery shards for drainage.


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## LWP (Nov 23, 2020)

abax said:


> What you do is buy clay pots and drill holes or slots in them. Ain't hard. If you break one
> now and then, you've got pottery shards for drainage.


TIP: Soak clay overnight in water ... they will drill much easier with much less breakage. . .


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## eds (Nov 23, 2020)

abax said:


> What you do is buy clay pots and drill holes or slots in them. Ain't hard. If you break one
> now and then, you've got pottery shards for drainage.



I did consider that but baulked at the idea so settled for an inverted net pot in the bottom instead which seems to be working ok for the three hybrids I have!


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## Ozpaph (Nov 25, 2020)

great tips!


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## SouthPark (Nov 25, 2020)

Just getting back to the original photo at the beginning of the thread ------ the leaves are relatively light yellow-green ..... chartreuse coloured.

Were the leaves always like that in colour? Or did the leaves start out as darker green, and then fade to this colour, followed by the rot?


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## monocotman (Nov 25, 2020)

The leaves went pale when the rot arrived. It’s just a photo of a dying plant!
David


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## SouthPark (Nov 25, 2020)

monocotman said:


> The leaves went pale when the rot arrived. It’s just a photo of a dying plant!
> David



Thanks David! All the best! Hopefully this one pulls through and makes it!


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## monocotman (Nov 25, 2020)

Sorry but it went to orchid heaven soon afterwards!
Hopefully this episode has improved my culture and there won’t be any more deaths due to poor culture,
David


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## DrLeslieEe (Nov 25, 2020)

Wow total clean up. Doesn’t it feel good?
Looks great and fresh.

Sorry about Angerer... she was a beauty.


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## DrLeslieEe (Nov 25, 2020)

monocotman said:


> Sorry but it went to orchid heaven soon afterwards!
> Hopefully this episode has improved my culture and there won’t be any more deaths due to poor culture,
> David


I think you had good culture the whole time! 

Now problems arises and you corrected them. It’s ever ongoing even with me.


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## DrLeslieEe (Nov 25, 2020)

Btw if they sit in planters, are pots raised from sitting directly in water? If you didn’t pot with clay pellets in lower inch, then you must not let them sit in water with orchiata.


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## monocotman (Nov 25, 2020)

Thanks Leslie,
the pots in planters were sat on stones all the time. It’s just that occasionally the water would come above the stones in summer when I watered more often and I didn’t notice. Now I know better!


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## SouthPark (Nov 25, 2020)

MM ------ as this thread has the title of 'cattleya rot' ----- I will mention some nice things that give all orchid growers confidence/hope in orchid growing. I haven't had a catt rot or even die in over a few decades of catt growing. I have lost a total of 4 catts though ----- but this was back when I first started orchid growing. That was when I was a newbie. But learned some important things from that - which amount to just a short list of tips ----- quite short. And sticking permanently to the basic tips definitely helped me have no issues - zero issues.

Although ----- I did inadvertently scorch a few catt leaves during peak sun scorching conditions - for some of my sun-hardened catts, but was not life threatening. All under control.

One main thing I stick by is to try make conditions tough for whatever unwanted organisms might/could grow inside the pot and/or in/on the roots ..... and also on the leaves and stems.

The way I water - is by sending most of the water into the media toward the outskirts of the pot ----- have the water flow into the media toward the sides of the pot. Pretty much like a waterfall cascade down into the media - the region along the walls of the pot. The media there gets very wet, but a dry gradient toward the centre helps with water movement and evaporation and humidity within the pot (or that's what I reckon anyway). My pot is wide enough so that the media in the whole pot doesn't get water-logged/saturated when I do the watering. The roots of my catts are generally regular ones ----- the ones that are not adapted to watery growing conditions.

I put much less water toward the centre of the pot ----- and sometimes none. The roots sometimes need to get their nutrients, so I figure that they at least sometimes need to get slightly wet in order to pick up whatever is still hanging in the media (like fertiliser, mag-cal etc). I apply 'weak' fertiliser and mag-cal ---- just once a month.

I do watering generally each morning. But watering every morning is not actually necessary. Even in very dry conditions, I've had somebody help me with manual watering (spray wand) with 2 days of no water. I just like to get in there to do the watering each morning - which allows me to keep an eye on all my plants ------ just to make sure they're all fine.

Sometimes - I allow the media to just dry out - including the roots, which probably does make things tough for certain unwanted organisms that might want to do their stuff inside the pot and in/on the roots. I just so happen to grow all my catts in scoria. I'm sure that I could grow bark or bark/perlite mix too. But I just use inorganic media in my tropical conditions.

Natural and gentle air-movement is good in the growing area. The air moves around the leaves and stems and all, and down through the media in the pot. My pots are all good drainage ones - sitting on drainage grates, that prevents the pot bases from sitting in any drained water. The drainage grates also allows all holes to get air into (and out of) them.

The temperature is generally quite nice for the orchids, and the roots are never watery and cold for any lengthy period of time.

So after a few decades plus ------ zero issues -- no losses of any catt, and no rot. But I did have a dendrobium beetle chomp a flower spike in half and even take out a catt leaf this season ------ but dealt with nicely by using carbaryl.

So for orchid growers out there ------ when the growing conditions are continually kept satisfactory ----- continually ----- the orchids can really do what they're supposed to do - grow nicely and healthily indefinitely. If the nursery growers at orchid nurseries can grow their plants really well, then so can us home grower orchid fans.

Although - I do have the benefit of tropical conditions here, which cuts down on a lot of effort, as compared with snow country conditions etc. But the same thing applies ------ aiming for continued satisfactory conditions for the orchids to grow.

I'm also posting this because your orchid didn't make it due to rot. So just mentioning a little about what I do for my orchids at home ----- so could possibly become useful to somebody else too. Each grower has their own ways of doing things. We just pick and filter and eventually all come up with a system that works well for very long times.


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## monocotman (Nov 26, 2020)

Southpark,
thanks for the information. 
It’s so interesting to hear how different people grow their plants in different parts of the world. The beauty of the internet and this forum.
If I were to water my catts every day they would all be dead in 6 months, but in your tropical conditions it works very well.
Stephen Van Kampen on YouTube has some interesting videos and also waters his catts every day and they grow very well. But he is in Texas where the summers regularly top 100 degrees f.
I take your point about watering around the edge of the pot. This is where most of the Catt roots end up after a year or so anyway so watering there makes a lot of sense. Avoiding waterlogged compost especially when you have bigger pots that take longer to dry out is critical.


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## SouthPark (Nov 26, 2020)

Most welcome David! Sure is ------ this is a fantastic feature of these orchid forums, where we can discuss the various setups we have. I think it's great how you're beating the issue by quickly acting upon what you saw ----- and you most likely have everything sorted and under control. You have an ouststanding orchid collection - along with the other members here. Also fantastic how you guys (and girls) in USA and Europe just import the wonderful orchids like that.

I haven't tried before, but I expect a long and expensive road (and probably risky too - as in orchid not making it through the trip and quarantine/fumigation etc) to do that sort of thing in Australia ----- importing orchids that is. It's probably expensive to do in USA and Europe too ----- but just guessing more do-able than in Australia.

Thanks David --- for mentioning SVK. Totally agree with you! He does make interesting and very good videos on youtube. I watched some of his catasetum growing videos, and his cattleya growing ones. The videos are presented really well.

True! The catt roots eventually gather and build up along the wall edges. Absolutely agree with you about undesirable water-logging of media - which can be easy to do in large pots with lots of water just dumped everywhere into the pot. The root-drowning slurry mix can be deadly for sure! The edge watering is one way to get around some issues. And another way is to use shallower pots (readily available) ----- and the edge watering also works very nicely for shallow pots too. But the grower also has the option to water the whole media too ----- depending on their own situation and growing environment. Some nice flexibility there.


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