Orchid Insect and Disease Control-Part 1: Cymbidium Leaf Markings

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Name: Joshua
Melbourne, Victoria, Australia (Zone 10b)
Köppen Climate Zone Cfb
Region: Australia Bookworm Cat Lover Lilies Orchids Irises
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Australis
Nov 23, 2017 11:35 PM CST

Plants Admin

I thought I might add some photos I have taken of various leaf markings on Cymbidium leaves and their causes in order to help others diagnose possible problems with their plants.

Scale Insect Damage
The particular plant shown in this photo had a few scale insects on it when I obtained it (apparently the grower had had a bad season for scale). It tested negative for viruses.
Thumb of 2017-11-24/Australis/c0d883


Sunburn
This is the early stages of sunburn, which I've noticed tends to occur on the highest point of the leaves (usually where they arch).
Thumb of 2017-11-24/Australis/ed28f2


Water Quality Issues
Some Cymbidium species are really fussy about their water quality (i.e Cym. devonianum, Cym. erythraeum, Cym. iridioides and Cym. tracyanum). They tend to suffer leaf tip dieback and necrotic spotting on the last part of the leaf. This particular plant is iridioides; it tested negative for viruses. The grower remarked to me that this is a common issue with the species. Note that the leaf mottling is a separate issue and not likely to be water quality.
Thumb of 2017-11-24/Australis/175d09 Thumb of 2017-11-24/Australis/6cd7da


Environmental Mottling (aka Chlorotic Bleaching)
It seems that temperatures on the extremes of what a Cymbidium can tolerate may induce leaf mottling. This is not temperatures that are hot enough to cook the plant or cold enough to freeze it, but close enough to the edge that they start to have a visible impact on the plant. C. Mausteller writes on his blog about the impact of high temperatures on his Cymbidium collection; his devonianum hybrids in particular showed similar mottling as a result of exposure to temperatures around 43-44°C. At this time, I am not sure if other factors can also cause these symptoms.

Both plants in these photos tested negative for viruses.
Thumb of 2017-11-24/Australis/135146 Thumb of 2017-11-24/Australis/0473c6


Odontoglossum Ringspot Virus (ORSV) Symptoms
This is what ORSV can look like on a Cymbidium. I thought these photos were particularly important to include, as I have found it difficult to find good photos of ORSV symptoms online (perhaps because it can be variable). This plant tested positive for ORSV and was disposed of not long after I took the photos.

Note the chlorotic patch that is close to the end of each leaf. The leaf on the left is showing the underside and has a much larger mark than on the leaf on the right.
Thumb of 2017-11-24/Australis/07b7ed

One of the leaves also had these linear necrotic marks. Note that they are sunken and different to the necrotic spots on my iridioides. There is also some mottling around it, although not as obvious as the leaf tips.
Thumb of 2017-11-24/Australis/3c8627 Thumb of 2017-11-24/Australis/ec23fc


I hope these photos help others to identify possible problems with their Cymbidiums!
Plant Authorities: Catalogue of Life (Species) --- International Cultivar Registration Authorities (Cultivars) --- RHS Orchid Register --- RHS Lilium Register
My Notes: Orchid Genera HTML PDF Excel --- Lilium Traits HTML PDF --- Lilium Species Crosses HTML PDF Excel --- Lilium Species Diagram
The current profile image is that of Iris 'Volcanic Glow'.
[Last edited by Australis - Nov 27, 2017 4:24 PM (+)]
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Name: Lin
Florida Zone 9b, 10a

Region: United States of America Deer Region: Florida Charter ATP Member Million Pollinator Garden Challenge I was one of the first 300 contributors to the plant database!
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plantladylin
Nov 27, 2017 10:19 AM CST
Joshua, what a great photo display and very helpful in identifying orchid issues. Thumbs up I think it would be really helpful for novice growers if we could have a "sticky" at the top of the Orchid forum with information like this!!
~ Playing in the dirt is my therapy ... and I'm in therapy a lot! ~


Name: Joshua
Melbourne, Victoria, Australia (Zone 10b)
Köppen Climate Zone Cfb
Region: Australia Bookworm Cat Lover Lilies Orchids Irises
Seed Starter Annuals Container Gardener Garden Photography Forum moderator
Image
Australis
Nov 27, 2017 4:25 PM CST

Plants Admin

Thanks Lin. There is a direct link to the parent article on the Orchid forum as well:

The thread "Article - Let's have fun growing Orchids by Steven A. Frowine" in Orchids forum
Plant Authorities: Catalogue of Life (Species) --- International Cultivar Registration Authorities (Cultivars) --- RHS Orchid Register --- RHS Lilium Register
My Notes: Orchid Genera HTML PDF Excel --- Lilium Traits HTML PDF --- Lilium Species Crosses HTML PDF Excel --- Lilium Species Diagram
The current profile image is that of Iris 'Volcanic Glow'.

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