Q.“PROSTRATUS” Rosemary
1st of the year in early spring I planted a Rosemary herb (Rosmarinus officinalis). I noticed today it has an almost white fungus or some sort on the plant. Do I need to treat it or am I over watering the plant?
Your Rosemary has Powdery Mildew.
Here are some links that will help you with care and treatment.
https://www.gardeningknowhow.com/edible/herbs/rosemary/growing-rosemary-plants-rosemary-plant-care.htm
https://www.gardeningknowhow.com/edible/herbs/rosemary/white-powder-on-rosemary.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm