It is hard to say exactly what is causing your yellow and black leaf marking. But i have a couple of guesses. The yellowing leaf tips may be related to your watering habits. Like Cathy said, your orchid needs more than a soak half way up the pot. You should consider flushing the pot out from the top to water it. Also depending on the orchid, your growing conditions, and the potting mix, you may need to water more often than once a week. It looks like you may have some shriveling pseudobulbs. This along with the yellowing leaf tips could suggest that your orchid is not consistently getting enough water. The small black spots are likely from sun exposure. Some orchids are predisposed to developing black spots at higher light. These small black spots are not much to worry about. If you are concerned about them, moving the orchid further away from the window should keep new ones from forming. I am sure more experienced others will also assist you.

I've recently purchased a Colmanara wildcat 'Green Valley' online. The plant arrived in good shape except for these spots. Are these marks of previous sunburns, or fungal spots? Or just signs of physical damage?? Please help :( Note: I'm from Dhaka, Bangladesh. The city has a distinct monsoonal season, with an annual average temperature of 25 °C (77 °F) and monthly means varying between 18 °C (64 °F) in January and 29 °C (84 °F) in August.

Thank you for getting back. I agree with the above statements. I am not certain it is fungal/bacteria but you could try a systemic fungicide, wait for new leaves to develop to see if they develop the same spots. There is a Phal virus which presents in a similar pattern. I would keep your plant separated from your other orchids and treat it with a systemic fungicide. When new leaves develop and if they show the same spots, I would personally discard the plant. Hopefully it is fungal. Jane

It’s not uncommon for orchids to get leaf spots, it’s most likely fungal or bacteria, some plants are more susceptible than others. I would worry if they grow larger or spread. I wold keep it away from other orchids and avoid getting water on the leaves. The most effective treatments are pretty toxic and might damage the flowers so I would wait until it’s finished flowering and you are able to move it outdoors to treat it. You probably don’t know where the plant was or how it was treated before you got it. A stressed plant is more prone to infection, I’ve also read that too much fertilizer can make the leaf cuticle thin and prone to infection. Check the flowers when they open, deformities or color streaking can be a sign of a bigger problem.