Common Tree DiseasesMany common tree diseases result from fungal infections. Fungi are parasitic microorganisms that feed off the tree. Some fungal tree disease may result in observable mushroom-like growths, while others are impossible to see with the naked eye.Bacteria and insect infections can also cause tree disease, although less often than fungi.Maple Tree DiseaseMaple trees are susceptible to several common tree diseases, including powdery mildew disease, sooty mold tree disease and verticillium wilt. Because so many types of tree disease target maple trees, gardeners should monitor a maple tree closely for signs of fungus or damaged leaves.Oak Tree DiseaseWith a height of 60 to 70 feet and a canopy as wide as 50 feet, a fully grown oak tree dominates the landscape. Like the maple tree, an oak tree can be the target of several common tree diseases, including fungal infections, root rot and powdery mildew. Insects such as aphids, borers and twig pruners can also damage an oak tree.Root RotRoot rot is a particularly insidious tree disease. Often caused by fungi, root rot slowly damages a tree's root system, interfering with the tree's ability to take in sufficient nutrients and water.Root rot weakens the tree's root structure, making it possible for a strong wind to blow the tree over. Serious root rot can also cause a tree to fall without warning.Signs of Common Tree DiseaseSigns of tree disease are not always observable until the tree is very unhealthy. If you see any of the following symptoms you may have a sick tree:Broken rootsCankers (dead areas of bark, branches or tree trunk)Conks (a mushroom-like growth on the tree)Crumbly woodDark spots on leavesDeep splits or cracks in barkDefoliation (leaf loss)Evidence of boring insectsShort brown needles on a conifer's new growthSigns of fungal infections in rootsWhite powdery dust on leavesWilted, pale leaves.Treating Tree DiseaseProperly diagnosing and treating common tree diseases requires an arborist. An arborist can safely spray or inject the tree with the appropriate treatment. If the tree cannot be saved, an arborist can safely remove the tree. Need More Help? If you need professional help with your project, LendingTree Home Pros can help. The good news is that LendingTree Home Pros maintains a directory of home service professionals and can match you with a home pro in your area. All the home pros listed in the LendingTree Home Pros directory are properly licensed and insured and are backed by a $10,000 money-back guarantee! Let LendingTree Home Pros help you find a pro today!