Prevention. Oak wilt can be very expensive to control, but prevention is effective. To prevent oak wilt, do not wound oaks from April through July, which is when oaks are most susceptible to infection. This is particularly important in the high-risk area (see map on our Oak Wilt main page).
Controlling Existing Infection Centers
Disrupting the connections between the roots of infected and healthy trees limits the spread of oak wilt and is an effective control measure. Infected trees and their roots will usually die before root grafts can be re-established.
Oak wilt kills an oak as quickly as 3 weeks to 6 months. The cost per tree for the fungicide treatment is roughly $15 per inch of tree diameter measured at chest height.
What to do if your tree has oak wilt - If your oak tree has been diagnosed with oak wilt, have it removed ASAP to stop the disease from spreading. Once the tree has been cut down, have all of the roots around the tree severed so the disease cannot pass to neighboring trees.
Once an oak tree is infected with the oak wilt fungus, the tree will die and there is no treatment to save the tree.
Spread through Roots
Infection centers among live oaks in Texas expand at an average rate of 75 ft per year, varying from no spread to 150 ft in any one direction.
White oaks can be treated with propiconazole once they display early symptoms of oak wilt.
It may be burned up or taken to an approved yard waste facility.
If there is concern that a red oak may have been infected with oak wilt, then its wood should be immediately burned, buried, or chipped. Fire will kill oak wilt, and there is no risk of spores being transported by smoke.
Pruning between April 15 and July 15 should be strictly avoided because this is when beetle activity and viable spores are most prevalent across the landscape. If pruning an oak is absolutely necessary during this time, wounds should be immediately sealed with pruning sealer or water-based paint to prevent infection.
Live oak (Q. fusiformis) is a member of the white oak group and is the most common and abundant oak in central Texas. While live oaks succumb to oak wilt in the greatest numbers, they are intermediate in susceptibility to the disease with a small percentage (< 20%) surviving infection.
An average cost of treatment is approximately $11.00 per DBH. Dose rate of formulation and cost are determined by your tree's diameter at breast height (DBH). Starting at 4½' up from the base of the tree, measure the circumference of the tree's trunk in inches with a measuring tape.
How much does treatment cost? Fungicide treatments are based on the diameter of the tree and therefore vary quite a bit. The average tree costs about $250 to treat once. However, there are discounts available for larger projects.
A good indicator of oak wilt infection is a carpet of leaves under an oak in mid-summer. Red oaks infected with oak wilt lose about 90 percent or more of their leaves in 1–2 months; bur and white oaks quickly lose leaves from a few branches during the summer over several years.
A couple of key concepts are important to remember: First, there's oak wilt. To avoid the chances of being infected with this deadly disease, pruning should be avoided, if at all possible, from February through June, when the insects that vector this disease are most active.
Trees in the red oak group generally die rapidly, usually within weeks or months after infection. Treatment will not save an infected red oak. 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.
Finally, I'd like to note that chainsaws do not transfer oak wilt and are self-sterilizing on account of the operating temperature exceeding the temperature that the fungus can live in.
(Note: Burning firewood with oak wilt spores does not spread the fungus! Fungal spores burn, too. The risk comes from transporting infected firewood and storing it where the spores can be picked up by beetles and carried out to infect nearby healthy oaks.)
Stopping the spread of Oak Wilt involves a combination of strategies, including minimizing pruning during the active growing season, removing infected trees, severing root grafts, and using fungicides.
Pruning oak trees in winter greatly reduces the risk of an oak wilt infection as the beetles and fungal mats are not present at that time of year.
The disease is a particularly serious problem for species in the red oak group such as northern red, northern pin and black oaks. Once wilting symptoms are apparent on a red oak, the infected tree will lose most of its leaves and die within approximately one month.
Disease Characteristics
Oak wilt is identifiable by the rapid pattern of wilting starting from the top of the tree and progressively dying down to the bottom, and on specific leaves, wilting from the edges to the base.
The Essence of the Different Laws
The oak tree law California allows individual property owners to cut down and remove oak trees within their properties but they will have to seek and obtain the permission of the local county. The underlying principle here is that if an oak tree has gone dead, it has to be removed.
Oak wilt typically causes red oak leaves to turn brown around the edges while the veins remain green. Leaves are rapidly shed as the tree dies. Conversely, in live oak with the sudden oak death pathogen, the veins first turn yellow and eventually turn brown. Leaves are often retained on the tree after it dies.