Olive trees (Olea europaea) produce their fruit in fall, as long as they're healthy. Considered invasive in some areas, olive trees grow in U.S. Department of Agriculture plant hardiness zones 9 through 11. When the trunk of your olive tree becomes damaged, it requires some care to help it heal properly so the tree can continue to thrive.
How Damage Occurs
Pruning commonly creates wounds on an olive tree, but just on the branches. These aren't the main source of structural integrity for the tree and are easy to remove if problems occur from pruning. Because the trunk helps the tree stand upright and moves nutrients from the roots to the branches, when it's wounded, the tree could falter or die. Damage often occurs from lawn equipment. Mowers can scrape the tree or throw rocks against the trunk, string trimmers peel away the bark and pruning shears can slip when you're removing suckers close to the base of the trunk. Lightning strikes also cause damage.
Tree wound sealants cause more harm than good for most trees. These dressings are typically petroleum-based and you're supposed to paint them on the tree wounds. The idea is that the dressings block disease and pests from entering the tree through the wound. Instead, they tend to lock in diseases, such as olive knot, and pests, and they may prevent the tree from healing itself. Like many trees, olive trees don't grow new bark when it's chipped away. Instead, the trees develop callus wood, which looks like a knot that pokes out where the wound once was. When you cover the wound with a sealant, the tree can't cover the wound with necessary, protective callus wood.
Cleaning Away Bark
Caring for an olive tree wound starts with cleaning up the edges. Trimming away loose bark helps prevent moisture from seeping behind the bark into the trunk and causing rot before the callus forms. It also helps the callus grow by giving it clean edges to start from rather than jagged, loose bark.
Several types of fungus commonly infect olive trees, including olive knot and olive leaf spot. Wound calluses often grow slowly, giving these fungi time to enter through the wound and infect the tree. Although you shouldn't use sealants on open trunk wounds, spraying the wounded area with a fungicide discourages fungal infection without harming the tree or delaying the healing process. Copper fungicides are effective against olive knot and olive leaf spot, as well as many other diseases. Use a ready-to-use copper spray to treat wounds on an olive tree, following the safety instructions on the label.