Oak trees are popular trees for the home landscape because of their large size and attractive appearance, as well as the bright leaf color changes they undergo in autumn. Oak trees can live for many years with proper care, but a diseased oak tree can die and cause a number of problems for a gardener, whether through the spread of disease or a falling tree. Treating a diseased oak tree and bringing it back to health is the best way to avoid serious problems.
Examine the oak tree for the areas affected by disease. This can include visible damage to the roots and branches, wilting branches, discolored leaves, leaf spots, peeling bark, holes in the bark and dead branches.
Irrigate the soil around the base of the tree to help drain away any excess water. Oak trees growing in standing water are more susceptible to harmful fungal diseases like root rot, which attacks the tree from the roots and can kill it if left untreated.
Sanitize a pair of pruning shears with wood alcohol. Wood alcohol will prevent the pruning shears from transmitting disease from sick branches to healthy ones when the tree is pruned. Use wood alcohol in between cutting each branch to limit the possibility of transferring disease to healthy portions of the tree.
Cut any dead branches off of the oak tree, as rotting wood provides a place for harmful insects and fungi to live and can house disease. Cut off dead branches at the nearest adjoining limb of the tree, or at the trunk of the tree. Remove as much of the branch as possible to limit the amount of dead wood that remains on the tree.
Prune any branches that show signs of serious infection, including branches with dead, dropped or wilting leaves, branches with fungal cankers or spots and branches that have begun to die. Cut branches at an angle to promote the return of healthy growth from the oak tree.
Burn or dispose of all branches immediately to remove them from the area and prevent them from spreading disease to other trees or garden plants.
Apply a pesticide or fungicide to the oak tree to kill off the source of the disease. Follow all directions on the fungicide or pesticide for best results. Apply the chemicals as often as needed according to the directions to help kill and control the disease.