Hi guys.. Has anyone has this problem on their plants before? I don't know what it is, it looks dusty and makes grayish speckles all over the leaves of my orchids and some neps. I had a small problem (of this) on one of my orchids last year but never so seriously before. I just scrubbed it and it came off. no insects underneath. Any suggestions on what it is and how to prevent it? TIA..
