The two groups were those with hyperparathyroidism with calcium levels below 11.0 mg/dl (2.75 mmol/l) and those with calcium levels above 11. The result: NO DIFFERENCE! People with calcium levels of 12.5 do NOT have more symptoms, or stones, or osteoporosis, or fatigue (or anything) than people with calcium of 10.5.
Sooty black mold is a fungus that can appear on the surface of plant leaves, stems, twigs, branches and even fruits. The fungus does not harm or feed off the plants, but instead gets its nourishment from honeydew. Honeydew is a sticky, sweet substance that certain insects secrete. When sooty mold spores are carried by the wind and land in the honeydew, the fungus feeds on the honeydew and grows, covering the plants and causing a charcoal-like sooty coating of mold. When your plants have black sooty mold, your real problem is caused by the insects, such as aphids, whiteflies, mealybugs and scale.
When spores of the sooty mold fungus land on it, they begin to grow, using it as a food source. If you look very carefully at your lemon tree, I think you will find the insect that is feeding the mold. Check growing branch tips, leaf undersides and stems.