OAK WILT

What Is Oak Wilt?

Oak Wilt is caused by a fungus (Ceratocystis fagacearum) that affects nearly all species of oaks and is particularly aggressive when contracted by Red Oaks. This disease is a major problem in the eastern and central United States, including the greater Madison area and all of southern Wisconsin.

The Oak Wilt fungus kills the oak tree by infecting the vascular system (xylem). This elicits an immune response from the oak tree which then begins to plug the “tubes” in the xylem in a attempt to stop spreading the disease. This stops the flow of nutrients and water and results in either tree death in the red oak subgenus, or dead branches in the white oak subgenus.

All oaks in the Greater Madison area are susceptible to Oak Wilt, however the Red oak subgenus, including Pin oak, Scarlet oak and Black oak are more susceptible. Trees in the red oak group generally die rapidly, usually within weeks or months after infection. Treatment will not save an infected red oak, so preventative treatment is a must. Trees in the White oak subgenus, such as Burr oak and Chinkapin oak can generally be treated for Oak Wilt and will recover within a year of treatment.

The benefits of this “I.V.” or direct injection method as opposed to other less-effective soil injected methods are many:

• No chemical is released into the environment.
• The prescribed chemical is delivered to the tree with no waste.
• Adjacent plants will not be affected.
• Beneficial soil microorganisms are left unharmed.
• There is no chemical exposure to pets or children.

Oak Wilt Prevention

Many Madison neighborhoods are lined with irreplaceable 80-200+ year old oak trees. Just like in modern health care, it is often better to be proactive than reactive. This is why a health assessment of your trees is necessary. If appropriate, therapeutic treatment of propiconazole fungicide may be prescribed to assure and infection can never take hold.