Thanks to both of you for your thoughts and sorry for my late reply.
Emma, thank you, I also really like the cyms. I really couldn't resist buying them. Now I have to get a green house
Regarding #3: Actually it must be the lighting. There is no yellow striking on the leaf.
Do you happen to have a link a direct link to this greenhouse chat? I wasn't able to find it on their site.
Terry, do you have any recommendation for a insecticide suitable for orchids? Actually it also has been my first thought that it must be some kind of insect bite, but although I've thoroughly checked all my plants I wasn't able to find any living creature, nothing... So, would you still use an insecticide?
It was quite difficult to find a reseller in europe and to actually buy these strips, but I've bought a kit of 5 test strips from agdia in france and had to pa 84€. These strips are specifically for cymbidium mosaic virus and odontoglossum ring spot virus. They will arive tomorrow.
Regarding the look of the blooms, I actually do not have any picture and I also haven't been able to find many pictures of this plant in the internet - seems to be quite rare. So, other than that the blooms look quite nice and healthy I can't say anything else. Although the egdes of the blooms start to get brown. I really think they are just starting to wither, but as I am starting to get a bit concerned I've attached additional pictures and hope to get your assessment.
Oh and I will have to open one or two additional threads as I am experiencing other issues with my other orchids
Maybe I should have just started with one orchid instead of about 25 within just a few weeks...