Fusiform rust is a disease caused by a fungus. This disease deforms or kills pine trees throughout the South, including north Florida. Since the late 1950s and early 1960s, fusiform rust has caused extensive damage in slash and loblolly pine plantations. The disease is estimated to cause many millions of dollars in losses in Florida each year.

The fungus requires two living host trees, pine and oak, to complete its life cycle. The fungus cannot spread from pine to pine. Young oak leaves are infected in the spring by wind-borne spores produced on pine trees. The fungus does minimal damage to the oak leaves but later in the spring, wind-borne spores produced on the young oak leaves infect new pine growth. The fungus can stunt, deform, or kill pine trees. In many cases, the fungus weakens the tree causing branches to be easily broken off or the whole tree blown over by wind.

Two common, interesting symptoms of fusiform rust are galls and witches broom. Galls are abnormal growths and swellings that can be found on nearly every part of a plant. Galls can be caused by a variety of organisms including bacteria, fungi,