Hello. I live in Scotland. My avocado tree is over 6ft tall, and every so often produces groups of new leaves on different branches at the same time. However, other branches, mainly away from the window, are losing leaves, and the ends of the branches seem to be dying back. For some time now I've been aware of white fluffy patches & small white insects in places on the tree, which I now believe to be mealy bugs. I understand they weaken plants and I want to take action to protect the tree. I have an organic spray which contains sulphur, and which warns that this can adversely affect some groups of plants. Please could you advise as to it's use on the tree? Many thanks. [The product is called "Natural Disease & Pest Control" by Nature's Answer & says it contains Sulphur & fatty acids].