Oncidium with brown spots on leaves

[bmjayne]

Hello,

I have an oncidium that has quite suddenly developed two oval brown spots on a leaf. Around the spots appears to be a watery, dark green, translucent area as if the cells in that area are affected.

This plant has had a history of leaf spots, so I have been carefully watching the new, clean growth for months. These spots were not there two days ago, when I applied a preventative spray of Physan 20.

I have sprayed again with Physan 20 today, but the watery-looking area around the two spots has slightly expanded since then.

Any ideas? It seems as though the Physan is inadequate - maybe I need to get a systemic?



Thanks!