Gum is produced in response to any type of wound, regardless of whether it is due to insects, mechanical injury or disease. Gummosis most commonly occurs as a result of perennial canker, bacterial canker and the peach tree borer. However, gummosis can also be associated with Botryosphaeria cankers, certain viruses, adverse growing sites, winter damage, herbicide damage and many other factors. In Kentucky, gummosis is most frequently due to perennial canker. It has become one of our most destructive peach diseases, at least partially because of the high incidence of winter injury to trees in recent years.
Cankers gradually enlarge until infected limbs are girdled and then die.
Gummosis is usually associated with the cankers. The canker fungi overwinter in active cankers in living wood or in dead wood. Infection occurs where the bark is damaged or injured. Infection following cold injury frequently occurs in the crotch angles of affected trees. Other ports of entry for these fungi include pruning wounds, mechanical damage, insect damage and leaf scars.