The oak tree is a majestic tree in the genus Quercus of which over 500 species exist. The grand oak is common to many regions of the world particularly North and South America and Asia. Known for its large height and its many uses, the oak is an important tree. Its timber is used in the construction of many structures from buildings to ships and even drums and wine barrels. It is also used to make furniture, corks, and floorboards. It should come as no surprise then, that the strong, powerful oak is the national symbol of dozens of countries and states, and is even the official symbol of many political parties. The reverence of the oak has been holy: in Norse folklore, the thunder god Thor held the oak to be sacred.
Given its commercial, scenic, and even national importance those who tend or grow oaks can be distressed when their oaks develop diseases. For many who grow oak trees diseases should not be a problem given the resilience of the oak tree and its abundant tannin concentration, but as have recent media reports have shown, oak trees diseases can at their worst be rapidly fatal, such as the grimly named Sudden Oak Death caused by Phytophthora ramorum. Oak trees diseases comprise mostly of infections with different organisms including mainly bacteria and fungi or infestation with insects. The symptoms can be wide ranging, and often include discoloration of the bark or leaves, decreased or abnormal growth patterns of the tree and its parts, new growths and patches on the trees, and even death, hence, oak trees diseases can be a cause of great concern for their caretakers. But the diseases are not a homogenous group: some only affect specific species, or in specific geographical areas, or at specific times of the year.
If you suspect that your oak tree is diseased, it is important to deduce the disease because treatment will be according to the disease. This can be done using books, online guides, or by consultation with an arborist. Insect infestations, including galls, caterpillars, and moths may not themselves cause particular diseases, but will break the trees’ protective mechanisms, leech off its nutrients, and allow it to become highly susceptible to other diseases, which is way they may need to be controlled with an insecticide. The oak trees diseases that commonly affect the oak and are problematic for growers include fungal diseases such as anthracnose, caused by the fungus Apiognomonia quercinia, and powdery mildew. Both can lead to discolored, dead, or malformed leaves, and can be treated using chemical fungicides, and proper and timely raking and pruning. Chemical cures are not the answer for many oak trees diseases. Some oak trees diseases can be spread to other parts of the tree and to other trees so it is imperative to cut off the diseased limb, such as in the bacterial infection Wetwood, or cut and burn the entire tree in the case of Oak Wilt, a fungal infection.
Tips and comments
The best way to deal with many oak tree diseases is to regularly maintain the trees in good health such as regularly observing for signs of disease, watering them, particularly during dry spells, providing fertilizer, and timely raking and pruning. These measures will both prevent disease and help the tree recover and fight illness. Lastly, never hesitate to contact a reputed local arborist to receive expert guidance.