Oak wilt is a fungal disease caused by the organism Bretziella fagacearum that threatens Quercus spp.

The pathogen penetrates xylem tissue, preventing water transport and causing disease symptoms.

Oak wilt is a devastating exotic disease, killing some trees rapidly in a single season.

[11][12] Generally, red oaks (subsection Lobatae) display more severe symptoms with rapid and frequent mortality (particularly Q. velutina, Q. rubra, Q. ellipsoidalis & Q. coccinea).

White oaks (subsection Quercus) develop symptoms more slowly, rarely die, and can recover from the pathogen with damage limited to a few branches (particularly Q. alba, & Q. macrocarpa).

Oak wilt and the newly emerging emerald ash borer have the potential to devastate other important North American tree species with large geographical and cultural significance.

Range expansion of oak wilt to the Western United States (or to other continents) is a major concern.

The early 20th Century coincided with oak regeneration after significant logging in the Mid-Atlantic and Great Lakes region.

[22] It is particularly common in the Midwest where conditions are usually favorable for spore production and beetle activity during spring and early summer.

Oak wilt is a major problem in Illinois, Iowa, Michigan, Minnesota, Texas, and Wisconsin.

An abrupt demarcation of chlorotic veins and green tissue is often a distinguishing characteristic in live oak infections.

The mats grow to 10 – 20 cm in size, elliptical in shape, and grey in color with white margins that darken with age.

Alternatively, under ideal conditions (temperature, moisture content, wood pH) spore mats form under the bark of the dead tree.

[27] These spore mats (or pressure pads) increase in size, eventually breaking through the bark and releasing a fruity odor that attracts wildlife, including sap beetles, bark beetles, other insects, birds and animals, such as squirrels.

Insect vectors transmit the disease in spring to early summer in the Mid-West and late Winter in Texas.

This transmission method accounts for the vast majority of infections and is particularly devastating as groups of trees are killed.

The disease results from fungal spores clogging xylem vessels and preventing water and nutrient flow.

Tylose is an outgrowth of parenchyma cells created as a plant defense against pathogens, water deficiency, wounding, and heartwood formation.

Tylose formation signals senescence of adjacent parenchyma cells and secretion of secondary metabolites (called gums), which may include phenolics.

Tylose and secreted gums act as a barrier to slow the colonization of the pathogen and play an important part in plant defenses.

However, the action to compartmentalize the oak wilt fungus ultimately obstructs all water conductance, leading to death.

Any chosen method relies on specific landowner objectives; such as protecting high value trees, treating individual trees, halting or slowing the spread of an infection center, and reducing the number of new infection foci.

Propiconazole is a broad-spectrum systemic fungicide that interferes with the biosynthesis of ergosterol in cell membranes by binding to 14 alpha-demethylase.

Likewise, therapeutic propiconazole application does not eradicate the fungal infection, rather it delays symptoms and reduces mortality.

Mechanical separation of the underground root connections will not allow the disease to transfer to adjacent trees.

Notwithstanding, digging a trench (or plowline) four feet deep around infected trees is an effective cultural control strategy.

The plowline can be created with agricultural machinery, such as an excavator, rock saw, vibratory plow, and bulldozer with ripper or subsoiler.

The placement of a root barrier can offer additional protection to trenching, but increases total costs.

A geomembrane is a semipermeable textile (similar to landscape fabric) that physically blocks roots from coming into contact.

Tree removal involves felling and burying or burning the logs, ensuring all inoculum is discarded.