Yellow Spotting/Pitting on C. intermedia Seedling - Orchid Board

estación seca · #1 07-31-2024, 08:15 PM

I think it's partly related to too much light, leading to too much heat.

Not all photons are used for photosynthesis, nor reflected. Some generate heat in the leaf. Small seedlings have a greater surface area to volume, so they heat more than larger plants under the same light. If conditions are breezy the heat will be carried away. Seedlings in general are safer with dark green leaves, and light lower than would be tolerated by adult plants.

I have also seen something like this in Catts., Phals. and Vandas, when cool water hits warm leaves.

Has the temperature inside risen recently? That would lead to decreased cooling of the leaves, and also an increased temperature difference between leaves and the misting system. There is no harm in having a breeze blow on the leaves, other than needing to water more often.

I would try and move the plant further from the light, until the leaves are a deep green, and not yellowish green.

galguibra · #2 07-31-2024, 08:31 PM

Quote:

Originally Posted by estación seca

I think it's partly related to too much light, leading to too much heat.

Not all photons are used for photosynthesis, nor reflected. Some generate heat in the leaf. Small seedlings have a greater surface area to volume, so they heat more than larger plants under the same light. If conditions are breezy the heat will be carried away. Seedlings in general are safer with dark green leaves, and light lower than would be tolerated by adult plants.

I have also seen something like this in Catts., Phals. and Vandas, when cool water hits warm leaves.

Has the temperature inside risen recently? That would lead to decreased cooling of the leaves, and also an increased temperature difference between leaves and the misting system. There is no harm in having a breeze blow on the leaves, other than needing to water more often.

I would try and move the plant further from the light, until the leaves are a deep green, and not yellowish green.

Okay, that's at least a lot less stressful of a problem to have if that's the case !! I brought the light down to about 75% of what it was before, and adjusted the fan to move some more air in that part of my room. I don't think the air temperature inside has really been any different recently, but I have been trying to get the humidity down, since I was getting some peaks of ~75-80% before (basement units smh) and that's just not sustainable. The humidity is down closer to 65% these days, so maybe that lowered the plant's effective heat tolerance.

And now that I'm thinking about it a bit more, I did also start using warmer water for the daily soaks in the past few weeks than I had been when I was just spraying with water. The water temperature probably went from ~70°F to like ~85°F since I recently got a C. aclandiae seedling and wanted to help keep it warm without heating up the rest of my place. I don't ever cross contaminate the water/vessels between plants, but I definitely wasn't going to mix up different temperature fertilizer soaks haha. Maybe that contributed too, and then the combination of everything ended up being too much. Should I just stick to room temperature water to make sure the misting water isn't a temperature shock later?