* Update - I tried this and overnight it turned some of the leaves of my herbs black!
Homemade Organic Fungicide/Insecticide/Fertilizer
2 oz. of liquid seaweed (kelp)
2 tbsp. baking soda
1 tsp. liquid hand dish washing soap
1 quart (litre) water
Mix the ingredients above and spray on your Roses, or other plants,
once a week.
Liquid seaweed provides nutrients to keep the plant healthy
Baking Soda changes the leaf surface PH to Alkaline. Fungal
Molds need an Acidic base to grow
Soap helps the solution stick to the surface and acts as a mild