How to Manage a Phyllosticta Infected Orchid

[Orchid Whisperer]

I agree with Ray's fungicide recommendation.

I would also add that you should provide soluble calcium and magnesium. Low concentration provided on a regular basis with routine watering. Gypsum (or plaster of Paris) and Epsom salts, a teaspoon of each to a gallon of water. Once dissolved, add a few ounces of that solution, per gallon, to your regular watering. The Ca and Mg help with disease resistance. The solution also provides sulfur.

Older plant leaves should be removed if they start yellowing and showing signs of Phyllosticta scarring. You see less scarring if the plants get the proper nutrients, the proper sunlight for the plant, fungicide treatment, and supplemental Ca and Mg.