Answer: I can't tell from your question if yur ixora has a fungal disease or if it has sooty mold which is actually a coating on the tops of the leaves. Sooty mold is a result of insect feeding - usually aphids. If you control the aphids with insecticidal soap, the sooty mold will weather away. If the plant truly has a fungal disease, prune off the affected plant parts to stop the spread of the disease. You can then protect the unaffected plant parts with a garden fungicide. Good luck with your ixora.
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