Fungus is those black spots that appear, making it look like the succulent is rotting. You may note white or pale spots on succulent leaves. Talinum paniculatum "Limon" has chartreuse leaves and Talinum Paniculatum "Variegatum" has creamy white variegation. You may see this website on buy succulents online fine, powdery white substance under your plant. It is likely that it has mealybug. The jelly-like substance that exudes from the cut leaves is often applied to minor wounds or burns.