Dendrobium smillieae yellow spots on new growth

[jrengen]

I have a Dendrobium smillieae that is putting up two new growths. I just noticed the new guys have yellow spots on them, photos attached. I am wondering if this is water damage or what? Would love some expert advice.

[SaraJean]

Does yours have little sap like deposits on the back side of the leaf? First double check for insects by wiping down with some rubbing alcohol and a cotton ball, but I’m curious to see what others will say. This happens to my Den. smillieae as well. They seem to happen mostly in the spring-summer so I’m wondering if it might just be some sap spots that happen during a high growth growth period. This is assuming it is otherwise well cared for (plenty of water, light, warm temps, and some food this time of the year)

Those are some nice fat new growths, btw!

[jrengen]

I don't see any sap on the leaves. Checked already for insects, couldn't see anything. It's getting good water, light and food. I'm using MSU fertilizer weakly weekly. I thought it could need more magnesium, but don't know. The rest of the plant seems ok, maybe a spot here and there, but nothing really obvious. I moved it down the bench where there is a little more airflow. It will be interesting to see what happens.

[VeronicaUlloa]

Did you ever get an answer on this thred? My Dendrobium also has yellow spots which are very curious... any input?

[PuiPuiMolcar]

My Australian dendrobium have the same symptom, I was wondering if it was from my tap water or the lack of nutrient.

[VeronicaUlloa]

I don't think it's from either of those because I have been fertilizing and it's been raining enough to not have to water here in Miami, FL (US). I was thinking it was sun spots but am not sure.