Oak trees are some of the largest, most stately trees in many landscapes and yards. While oaks are generally hardy trees that withstand a variety of conditions, some problems can cause the branches on these giants of the landscape to wither and die. Dead branches are often a sign of poor growing conditions, illness or pest infestations. Prompt treatment can help reduce damage and promote proper growth.
Check the Number of Dead Branches
An oak tree that displays 10 per cent or fewer dead branches may simply be going through a natural stage of growth and renewal. Dead branches are a normal occurrence in healthy trees. The absence of leaves is not always a sign of a dead branch. Dead branches contain no leaves and feel brittle to the touch. Bending a dead branch will cause it to snap. A live branch without leaves may contain a foliar pest that eats away the leaves, making the branch look dead. Spraying the branches with an insecticidal soap may help eliminate the pests responsible for the damage.
Recognise Oak Wilt
Ceratocystis fagacearum, commonly called oak wilt, is a fungus that affects oak trees, especially in the central and eastern United States. This deadly disease first appears as wilting of the leaves in the late spring and early summer. Dead leaves fall from the tree and cause heavy areas of defoliation, leaving the oak branches bare. Dead branches often develop dark streaks below the bark. This fungus enters the trees through open wounds. Protect damaged oaks with wound dressings to minimise the risk of oak wilt disease.
Check the Roots
Dead branches on oaks and other trees can signal girdling, a root condition that inhibits the growth of new roots. Oaks with this condition may have dead branches and missing leaves on just one side of the canopy. Check the base of the affected tree for roots that seem to circle the trunk rather than spreading away from the tree. Removing the circling root will allow the other roots to grow freely outward and enhance the health of the oak tree.
Avoid Herbicide Over-spray
Weed killers that reduce the growth of weeds in your lawn can also damage the health of an oak tree. Oaks produce numerous lateral roots that run just under the surface of the soil. Applying an herbicide over these roots can cause leaves to curl and twist. Excessive amounts may lead to the death of some limbs. Avoid harming your oak trees by applying herbicides on calm days and keeping them off the soil under the canopies.