I'm thinking that if that's a fungus growing on your sprouting tulip, it may have been present in the bulb when it was planted, and it may just now be coming out and fruiting. Or the growing tip may have been damaged after it came up and fungus spores entered the tulip then. My suggestion would be to pull up and throw away any sick tulips, leaving only the healthy ones. There may not be anything wrong with your soil.
