Most welcome NZ.
If the spots just stay like that - and no spreading when gentle air movement is provided in the growing area, and leaves kept dry, then everything should be fine and under control.
I have heard that some growers had issues with copper spray on dendrobium. I don't know what concentrations they used. I did recenty test copper sulphate spray on a Den. moschatum ----- sprayed quite a fair bit on - just as a test, and no problems resulted at all ------ at
this link. The copper sulphate solution seen in the pics was quite nice and blue.
I also have Den. discolor to try it on too later.
I only tested as a ..... test. I think that much more testing should be done lots of times on various dendrobium - with recorded copper concentrations, and growing conditions etc ....... in order to really find out how the dendrobiums got impacted negatively by copper ------ when those growers used it that is.
So the moment, unless there's no other option - could certainly skip using copper on dendrobiums. I will try it on my Den. discolor very soon though!
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