Crown Rot Prevention in Large Greenhouses

[JAB]

So I was wondering how big nurseries / greenhouses that spray from over head either via hand sprayer or automatic, how do they prevent crown rot and water from accumulating in the nooks and crannies?

Was just thinking of this the other day.

 

[gonewild]

They don't prevent it but because the surrounding environment is correct the excess water does not induce rot.

Aside from that using flexible cultural practices when applying water reduces potential problems. Like water early in the day and not at all when conditions wont allow evaporation to dry up the greenhouse.

 

[Linus_Cello]

Also lots of air movement from fans

 

[Happypaphy7]

Rots still happen, including all kinds of other diseases as well.
Plants in greenhouses are not immune, and I won't say they are better off or worse off.
If anything, with so many plants crowded up, it serves for a great conditions for disease and pests to thrive.

Depending on the nursery, they practice preventative measure like spraying at particular season, usually hot and humid summer during which rots and other diseases are common.
This does not eliminate rot, though. It's just impossible to avoid.
The goal is to reduce the occurrence to the minimum possible to avoid financial disaster.

Other smaller scale nurseries may just pull out the bad plants and discard to prevent further spread.

Nurseries I've visited all had diseased plants. That's just how it is. Some had more and some had less. That was the only difference.

 

[Ray]

Exactly...water very early, when weather allows, and make sure there's good air movement. Speaking as a "small nursery/greenhouse" operator, where overcrowding can be a rampant issue, I found that with regular treatment with the Inocucor product, rots virtually vanished (which is why I sell it...).

 

[Dandrobium]

I have a rainbarrel where I apply 2-3 tablespoons of Physan before a big rainfall. This seems to minimize any rot/fungus I used to get. That would be a max dosage though, as additional rain would further dilute it during use.

 

[Redtwist]

On a similar topic, as someone who always worries about getting any water in the crown (mainly because temperatures here in the UK cant always be relied upon to evaporate water quickly, and because growing my plants indoors air movement can also be limited) do people think it is actually beneficial to occasionally 'flush' the crown/leaf bases? Dust and debris does accumulate in there over time, which I expect can equally cause health problems for plants in the end.

 

[gonewild]

I think it is a good idea.
But I usually flood the crowns when I water so they stay clear of debris.

On the other hand in nature they are packed with all kinds of crud.

 

[Stone]

They don't prevent it but because the surrounding environment is correct the excess water does not induce rot.

Aside from that using flexible cultural practices when applying water reduces potential problems. Like water early in the day and not at all when conditions wont allow evaporation to dry up the greenhouse.

I agree with this. Water does not cause disease, it can only assist it. My orchids in the shade house outside never get attacked by pathogens. In summer - and sometimes even in winter -I water late in the day. 4 or 5 pm and they remain wet all night unless it's windy.
The big difference is air movement and I suspect not just air movement but air exchange is also involved.

Unless you are rich, it is too expensive to move so much air and heat introduced air into a green house.
That's why so many tons of leaf fungicides are sold every year.

I think perhaps the volume x the time period of water falling on the plants in the habitat may also play a part.
When it rains in the habitat, the plants are showered for sometimes hours.
In other words they are constantly washed so what chance do pathogens have of building numbers?
Who here overhead waters their plants for 3 or 5 hours non stop and then follows that up with 12 hours of strong wind from gigantic fans connected to V8 engines?

 

[gonewild]

I agree with this. Water does not cause disease, it can only assist it. My orchids in the shade house outside never get attacked by pathogens. In summer - and sometimes even in winter -I water late in the day. 4 or 5 pm and they remain wet all night unless it's windy.
The big difference is air movement and I suspect not just air movement but air exchange is also involved.

Unless you are rich, it is too expensive to move so much air and heat introduced air into a green house.
That's why so many tons of leaf fungicides are sold every year.

I think perhaps the volume x the time period of water falling on the plants in the habitat may also play a part.
When it rains in the habitat, the plants are showered for sometimes hours.
In other words they are constantly washed so what chance do pathogens have of building numbers?
Who here overhead waters their plants for 3 or 5 hours non stop and then follows that up with 12 hours of strong wind from gigantic fans connected to V8 engines?

Exactly,
Mike until recently I thought the air movement (wind) was the major factor also. But now I think the other point you mentioned, Gas exchange, is more significant. For the last year and a half I have had a bunch of Phals growing under shade cloth. They get all the rain that falls here and that's a lot. Day or night and their crowns have never rotted. The reason I think it's not so much a factor of the air movement is because the shade house has walls and there is basically no wind or breeze. But they have an abundance of fresh air to exchange gases. So maybe crown rot and other bacterial diseases are aggravated by low levels of CO2 or high levels of some other gas.

 

[Ray]

OK, but now let's consider the Andean species that stay constantly bathed in fog. No rain to wash them clean, just wet, wet, wet...

 

[gonewild]

OK, but now let's consider the Andean species that stay constantly bathed in fog. No rain to wash them clean, just wet, wet, wet...

In regards to keeping them flushed clean when they stay constantly wet (moist) in the Andes they have a constant living active population of organisms keeping them un-polluted. That's why your Inocour works.

They stay wet at night and they do not rot. But also most of the plants are not very pretty all covered in moss and lichen.

 

[JAB]

Thanks guys!
Do you think species such as Dracula are more resistant to rot?

 

[gonewild]

Thanks guys!
Do you think species such as Dracula are more resistant to rot?

Than what?

 

[orcoholic]

Don't most of the orchids in the wild grow with their leaves pointing outwards, not upwards, thus preventing any water accumulating in the crown? The excess water just runs out of the crown. I've never had a mounted orchid show any signs of crown rot.

My guess is that most large facilities have a regular program for pesticide/fungicide/bacteriacide application. It wouldn't make financial sense for them to do otherwise.

 

[C. Rothschild]

Yes the place I go to said they use Consan 20 but they need a license to use it. I think that only applies if the plants are to be sold. Same thing with other chemicals if you read the fine print. No idea why.

 

[Stone]

Thanks guys!
Do you think species such as Dracula are more resistant to rot?

Some plants are absolutely more resistant. Eg; I have never ever seen Botrytis attack Sophronitis flowers where other species next to them are.

 

[troy]

If a flower is not flat and round the plant it's growing from should die anyways

 

[gego]

If a flower is not flat and round the plant it's growing from should die anyways

LOL you're something else. problem is they never die, the good ones does.

 

[phraggy]

I had a few plants that were limping along nicely in the greenhouse until I decided to put them outside in May and put them back in the greenhouse in Sept/Oct. In this part of the world we do not get seasonal weather we just get weather which is mainly temps between 12c and 22c ( and not many days of the warmer one!!) plus many, many days of wind and rain which has left the plants sopping wet most of the time. I have been amazed how the change has made them grow. No signs of rot but plenty of growth in the crowns with the most impressive growths being the roots. They are literally coming out from all over the place so I have put just one pic ( of renanthera ) to show the amount of root growth. The plants haven't been fed for 4 months.

Ed