Ring spot virus?

[bogdan]

Hello, dear forum that I read every night before going to sleep
While browsing the internet I found some photos of plant pathogens on the Missouri Botanical Gardens website that reminded me of the recent order of plants that I got without a heat pack in this first week of January. Two of them, Cattleya dowiana and C. trianae, have only a few of these spots that resemble the ring spot virus symptoms, but dowiana is also particularly yellowish. It just doesn't look in its prime.
I am attaching two photos, the first is C. trianae and the second an older leaf of dowiana. What is your opinion?

Thank you all

[katrina]

Neither look like virus.

The first looks like there may have been a scale insect or some other sucking insect...check it over thoroughly.

The 2nd, not sure but dowiana does have more yellow leaves when grown in the proper level of light. It is also very prone to rot if the roots do not dry quickly...especially when temps are cool. I probably wouldn't be too concerned over that but I would keep an eye on it to make sure it isn't spreading.

[Ray]

Why are the leaves wet? That's a great way to spread pathogens.

[Orchid Whisperer]

Especially the second photo: could be cold damage.

Keep the leaves dry, and keep the plants under close observation.

[bogdan]

The leaves were wet because I sprayed them with their bi-monthly Sunday Kelpak and magnesium sulphate treat. I don't usually spray them, even though I have fans running on them. Ray, do you think there is a pathogen to be spread?
i will watch them closely, but I also think that cold could be a cause.

Thanks for all the input

[estación seca]

KelpMax and magnesium sulphate do no good on leaves. Most orchids absorb next to nothing through the leaves, and rooting hormones wouldn't affect the leaves in any event. Try to keep warm-growing orchid leaves dry during periods of cool temperatures.

[bogdan]

Kelpak (not Kelpmax) is a trademark for probably the same thing as Kelpmax, but on their website it says that, among regular spray and fertigation, "Kelpak Liquid Fertiliser can also be used in standard aerial applications". So I am replacing the turboprop with a hand sprayer
Magnesium sulphate (epsom salt) is bioavailable via leaf as well, if I understood correctly when read in orchid books that spraying it helps intensify the green of the leaves. Don't know how the CAM metabolism may influence this.

Spraying the plants in the morning (two times a month) then running a fan on them under lights at 77 F for 11 hours (January) which I do anyway daily, did no harm and having done this today certainly didn't cause what I showed earlier.

Thanks

[estación seca]

Sorry about the misunderstanding about names. Not enough coffee.

Magnesium is necessary for synthesizing chlorophyll, so magnesium deficient plants can turn yellow.

Foliar spraying works with other plants, but not orchids. Orchids just don't absorb water through their leaves. Apply the magnesium to the roots. It is absorbed this way very effectively, but it can take a long time to replenish orchids deficient in magnesium.

[bogdan]

Thank you, now I understand.
Having this particularity of not absorbing water through their leaves, how do pesticides work, especially the systemic ones that need to be absorbed? Cutin-pesticide binding or something in that manner?

Or, having the stomata open during the night-time would mean that spraying before dawn is more effective?

[estación seca]

The systemic pesticides are absorbed through the roots. Most orchid stomatae are on the under side of the leaf.