I would think you are at a disadvantage mixing baking soda and milk, as the baking soda will stop to some degree what the milk is doing by sterilizing the milk with sodium, which is also along the lines of what cornmeal does, that being the attraction of natural fungal enemies such as trichoderma which in turn eat your disease as well if it runs out of preferred food. Milk is full of proteins, so even skim milk works. Proteins are very sticky, and it will form a protective layer. Thus the use of oil and soap (hopefully not detergent) are actually interfering with the biology of the milk protection strategy via inappropriate ionic charges or the inhibition of necessary oxygen (oils can preserve) for the development of the milk spore. Its good to spray at least weekly with the milk.
It is harder to control when things are wet outside. I just experienced a fight with septoria spot. It is not spotting the tomatos just leaves and stems. I thought it was early blight at first I have it every year, but this year being drier has helped. I trimmed and pruned for airflow and sprayed povidone iodine 10% at the rate of 3 tbsp per 1000sf of garden. The garden is currently in remission. Betadine is an iodophor which will kill candida and other serious fungus caused by yeast, and I weakened it further because those that shared the idea with me use 2 tbsp per gallon for soil drench and plant foliar applications. Plus, iodine is a nutrition supplement.
