something wrong with all my dendrobioum leaves
 

the leaves of all my dendrobiums are dying, not sure if that's a pest of some deficiency (i recently run out of fertilizer and changed)

https://lh3.googleusercontent.com/pw...-no?authuser=0

https://lh3.googleusercontent.com/pw...-no?authuser=0

please help me figure it out.
thanks.

You have spider mites. They are also on all your other plants, but they cause more damage to thin-leafed plants. They prefer warm, low humidity environments.

They can be controlled by spraying all surfaces of plants with 70% alcohol. They can also be controlled by spraying all surfaces with 2-5ml of liquid dish soap in 1 liter of water.

For long-term control try to raise the humidity, and spray all plant surfaces of all your plants with water every 1-2 weeks.

thanks.
when you say to spray with waster every 2 weeks, did you mean to wash the leaves with a jet of water? or just mist them with a thin spray to raise humidity?

Spraying leaves is inadequate to raise humidity, especially every 1 or 2 weeks.

Read this.

I mean get all surfaces wet with a water spray. This dislodges adults and kills eggs. Raising humidity requires other methods, as Ray mentioned.