Brown Leaves on a Live Oak Tree

Live oak trees are prone to a fatal fungal disorder.

Live oak (Quercus virginiana) is a 65- to 85-foot tall tree with a spreading growth habit. The tree is among the heaviest hardwood trees. The deciduous leaves are 2 to 5 inches long and dark green. A fungal disease causes foliage to wilt and brown.

Identification

Live oak trees are susceptible to oak wilt disease or live oak decline. The United States Department of Agriculture cites the disease as among the most serious tree diseases in the country. Oak wilt is caused by Ceratocystis fagacearum.

Damage

Initial symptoms of disease include the yellowing of veins that gradually turn brown and fall. With defoliation, the tree crown starts to thin. Affected trees wilt and die rapidly or slowly and completely decline over a period of one to six months. The disease spreads to healthy trees through roots or through insects like sap beetles.

Management

There is no fungicidal control for the disease. Take preventative measures like avoiding damage to roots and bark. Remove infected trees entirely with roots and dispose of wood by chipping. Avoid storing infected tree wood near healthy trees.

References

• University of Florida Extension: Live Oak
• Smithsonian Marine Station at Fort Pierce: Live Oak
• United States Department of Agriculture: How to Identify, Prevent and Control Oak Wilt