The oak is often considered the mightiest of trees. It symbolizes strength and courage. The ancient Romans thought oak trees attracted lightening and thereby connected the oak tree to the sky god, Jupiter and his wife, Juno, the goddess of marriage. Thus, the oak is also a symbol of conjugal fidelity and fulfillment. Transcending times and cultures, the oak has symbolized strength and endurance. For this reason it stands tall as the national tree of England, Estonia, France, Germany, Moldova, Latvia, Lithuania, Poland, the United States, Basque Country, Wales and Serbia.
There are about 400 species of oak trees worldwide. The acorn (which is actually a nut) is its fruit. Most acorns contain only one seed, and take between 6 to 18 months to mature.
Oak trees can live 200 or more years. The largest oak tree of record is the Wye oak in the community of Wye Mills in Talbot County on Maryland's eastern shore in the U.S.A. Estimated to be nearly 500 years old, it measured 31 feet, 10 inches in circumference, stood 96 feet tall, and had an average crown spread of 119 feet. Among its impressive characteristics were massive buttresses or "knees" at the base which helped support this huge tree.
A famous oak tree is the huge Major Oak near the village of Edwinstowe in the heart of Sherwood Forest, Nottinghamshire, England. This ancient tree is between 800 to 1000 years old and has a waistline of 33 feet. What makes this magnificent tree so popular is the belief that it was Robin Hood's shelter where he and his merry men slept.
Frequent diseases of oak trees
A serious threat to oak trees is the fungus Ceratocystis fagacearum, which causes Oak Wilt, a lethal disease to oaks, especially red oaks. Wood-boring beetles carry the spore of the fungus which actually causes Oak Wilt. Root Transmission may also be another way in which the tree is infested (by the underground root systems that often connect one oak tree with another). The fungus simply migrates from oak to oak by traveling through the vascular system of the roots in the same way that it spreads within the tree itself. The fungus clogs the vascular system of oak trees preventing the flow of water and nutrients. Once infected, the entire tree literally wilts and dies. The speed of the progression of the disease depends upon the species of tree infected. Red oaks can die from oak wilt in as short a time as a month. White oaks may survive as long as several years after infection. There is currently no cure for oak wilt.
Another frequent disease of oak trees is root rot which often shows no signs on the outside, but becomes evident when the tree falls during a storm. It is caused by a deadly fungus called Phytophthora ramorum. The disease is also known as Sudden Oak Death (“SOD”), because even though the tree may be infected with Phytophthora for a year or more before exhibiting the sudden change in foliage, killing an oak in just a few weeks. No effective methods exist to cure SOD. Another common disease is Bacterial Wetwood that affects the central core or bark of many shade and forest trees. No effective methods exist to eliminate wetwood disease. Slime is the exudate generated from wetwood on which insects commonly feed. Wetwood-infected tissue does not greatly alter the wood strength of most trees. Prevention of tree stress is the best management approach. Effective control measures do not exist.