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05 Jul 23 (Australia - sub-tropical climate)

My sage has developed a white spot on the leaves. What is it? Should I be concerned? Am I watering the plants too often.? John

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06 Jul 23 Celeste Archer (Canada - Zone 5a Temperate Warm Summer climate)

I tend to like using POWDERED Sulphur for powdery mildew. It is safe to use right up to the day of harvest ( EXCEPT ON GRAPES THAT ARE intended for wine - then 21 days before harvest). It can be sprinkled on dry -- but my preferred method is to dilute in water and spray. Ultimately you need to increase the air circulation around your plant. You might be over wetting the plant at times when it has difficulty drying -- if you have good air circulation this should not be an issue. Try watering BEFORE sun up -- then when the sun shines on your plant it will dry the plant. Mildews tend to stick better to damp leaves... so dry leaves in a windy area are less prone to powdery mildew. Additionally SAGE is considered a Mediterranean herb - and does tend to like dry conditions -- so the ground should dry out between watering -- watering well once every two weeks should be fine for an ESTABLISHED SAGE PLANT (seedlings need to be watered more frequently)... this might not be possible, because you may have plants that need more water nearby.

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05 Jul 23 (Australia - sub-tropical climate)

It sounds like it is a case of powdery mildew, which is a fungal disease, which are wind-borne spores. Best to remove the affected leaves. Treating the plant with an organic fungicide that contains potassium bicarbonate could be beneficial.

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