Sunken Brown Spots Den. Leafs
 

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These spots just showed up. I cut out the spots and applied Physan 20 to the plant. I hazard a guess it’s bacterial. What would you experts do?

What are your growing conditions? Temperatures day/night, humidity, lighting? Indoors or out?

It looks like secondary infection after leaf damage. Could insects have bitten the leaves?

Were the spots expanding?

In greenhouse, daytime Temperature 70-80, night 56 low, growing under lights about 4000 fc, There are occasional tiny flying insects I see (maybe from nearby soil tray for veggies). Have other orchids with some brown spots but none like these. Was worried they would spread quickly.

---------- Post added at 07:02 AM ---------- Previous post was at 07:01 AM ----------

60-70 humidity

For now I would wait and see if the problem is over. You might consider moving it to your house for a few days of lower humidity until you're sure it's not spreading.

Physan is mostly a preventative. It doesn't get inside the plant to treat fungi nor bacteria already causing damage. Because not all fungicides treat all fungi I don't recommend using them unless you know which fungus you have and you know it is susceptible to the fungicide you plan to use.