Hi, news photo after 1 day, i add crushed seashell...

(Seasshells)Calcium carbonate is not a fungicide. Might helps with slugs or snails but won't help with fungi. You are thinking of baking soda (potassium bicarbonate). Mix 1 tablespoon of baking soda and ½ teaspoon of liquid soap (not detergent) in 1 gallon of water. Or buy a fungicide and follow instructions. Spraying leaves not really recommended if you can help it. Stupid fungi. Hope you get it sorted. When it comes to wpm its better to never allow the conditions it needs to exist at all. Terribly hard to get rid of once you get it.