A common problem for the purple leaf plum tree is blossom blight, in which first the flowers, then young leaves, turn brown and wither, according to Grow Fruit by Alan Buckingham.
Once activated, helper T cells start to divide and to produce proteins that activate B and T cells as well as other immune cells. The killer T cell is specialized in attacking cells of the body infected by viruses and sometimes also by bacteria.
B cells mature in the bone marrow whereas T cells mature in the thymus.These are the cells responsible for developing immunity to particular types of bacteria and virus. B cells and T cells work in different ways. B cells produce antibodies.