TREE DISEASES

Dear HIW,

Can trees and plants develop cancer? Andy Hardman

Cancer is a disease that only animals get. However, plants can grow tumours in a similar way. These are cells that excessively multiply to produce an uneven growth. The cells in plants can’t spread to other areas of the tree because unlike human cells, the cell walls of plants stop them from moving around. Tumours in trees are often caused by bacteria, such as Agrobacterium tumefaciens. These are less deadly than cancer in humans because plants don’t have individual organs that are essential for life. If a tumour takes over a person’s brain, or another essential organ, they will die. However, when plants lose a part of them, they can usually bounce back by growing another branch or root.

Abnormal tree growths are sometimes called crown galls