Here is a simple way to isolate ergot mold. Did it once, but the instructions I had warned that the unadulterated ergot mold is so extremely potent that a drop the size of a marijuana seed could get 22 people high, so I chickened out when it came time to try it.
Take a loaf of black rye bread, and leaving it in the bag stuff bag and all into a plastic pitcher large enough to hold it. Get horse vitamins from feed store, and dissolve entire bottle in enough water to thoroughly soak your bread. Open the bag, pour vitamin water mixture into pitcher, let soak for about 15 minutes, and pour off excess water. Reseal the bag, place in a dark cool area, and leave it alone until you have a brick of mold instead of loaf of bread. It is my understanding that the vitamin mixture helps encourage ergot mold, while keeping other molds to a minimum.
Now, here comes the tricky part. remove your bread from pitcher, cut bag open, and spread nasty ass material on a sheet pan. Under a black light, the ergot mold will distinguish itself from other molds because it looks like thin threads of glowing purple amongst the other molds. using tweezers pick out the threads ( very time consuming ).
There you have it, but as I said, I chickened out at that point and just threw the whole thing away. Don't know if it worked, but the experiment did have the ultimate conclusion I was told to expect.
Oh, I should also warn that consuming raw ergot has some pretty serious health consequences associated with it as well.