Hello, I have a large conifer, approx, 16m. Not sure what type it is, photo attached. In the last week it has started producing dusty clouds which come out of the tree when the branches are disturbed. Are these clouds some kind of fungal sores? I have not seen the tree do this before during the 15 yrs I've had this garden. Apart from producing this cloud the tree looks fine. It has been suggested to me that tree may have a fungal disease, which could be dangerous to humans, and will need to be felled! Grateful for any advice!