As far as I know, milk doesn't work at all. Fungi hate acids, and milk is quite high in the PH scale (alkalic?). It's beter to use something with a lot of silica (which makes your plants more resistant). I've had great results with a Sodium Silicate (NaSi4) solution. However, the Na (sodium) can be harmfull, so dilute it some more than the package advises. This isn't very biological, but by using the right type of soil (with a lot silicates) you can make it so. Helps great agianst mildew and stemrot.
If there's a case of random stemrot, you cán use NaCl (kitchen salt) after cutting and cleaning the wound to prevent spreading. Mix this salt with vaseline to make it stick. It doesn't kill the fungus, but makes it inactive. I reported fungal growth of 0.01inch per 3 months after this treatment.