Oak Wilt and a Year-Round Tree Care Calendar

Live oaks and red oaks shade much of Austin, from Tarrytown and West Lake Hills to Circle C and the Hill Country suburbs. They're also vulnerable to oak wilt, one of the most destructive tree diseases in Texas. Many oak wilt infections start with homeowner activity: a spring pruning cut, a damaged root during a fence install, or firewood from infected trees. A little timing and care goes a long way.

How oak wilt spreads

The Texas A&M Forest Service's oak wilt resources describe two main pathways:

• Overland, by beetles. Sap-feeding beetles carry spores from fungal mats on infected red oaks to fresh wounds on healthy oaks. Fresh pruning cuts and storm wounds attract them.
• Underground, through roots. Live oaks often share connected root systems, so the disease can move from tree to tree through a neighborhood.

Red oaks (including Texas red oak and Shumard oak) are highly susceptible and usually die quickly. Live oaks die more slowly and can spread the disease to neighbors through roots.

The core rules

1. Avoid pruning or wounding oaks in the high-risk season, which runs roughly February through June when beetles are most active. Texas A&M Forest Service guidance emphasizes this window.
2. Paint all wounds on oaks immediately, year-round, with wound dressing or latex paint. This is one of the few cases where wound paint is recommended.
3. Don't move unseasoned oak firewood from unknown sources. Diseased red oak wood can produce fungal mats.
4. Clean pruning tools between trees.
5. Hire an arborist familiar with oak wilt, ideally an ISA-certified arborist.

Planning remodels around trees

Most tree damage during home projects happens underground. Before a fence, patio, addition, driveway or trenching for utilities:

• Know the tree rules. Inside Austin, protected trees (19 inches in diameter and up) and heritage trees are regulated, and work in their critical root zones may need review. See Austin tree rules. Suburbs have their own ordinances.
• Protect the root zone. Fence off a zone under the canopy during construction, and keep equipment, material piles and concrete washout out of it.
• Hand-dig or air-spade near roots for fence posts and footings, and shift post locations to avoid large roots.
• Avoid grade changes. Adding fill or cutting soil over roots suffocates or severs them.
• Schedule pruning for clearance outside the February–June window when possible, and paint the cuts.
• Call 811 before digging, for safety and to avoid service lines that may run under trees.

A month-by-month calendar for Austin

Watering established trees in drought

During long Austin droughts, even established trees benefit from occasional deep watering. Use a soaker hose or slow drip around the drip line, not at the trunk, and soak the root zone deeply every couple of weeks in extreme drought. Follow your water utility's watering schedule.

Signs of oak wilt

• Live oaks: leaves with yellow or brown veins (veinal necrosis), leaf drop out of season, and dieback that spreads to nearby oaks.
• Red oaks: rapid browning of the whole canopy in late spring or summer.

If you suspect oak wilt, contact an arborist or the Texas A&M Forest Service. Trenching to break root connections and treatment of high-value trees are options a professional can discuss.

Choosing replacement trees

Diversifying beyond oaks reduces risk. Native and adapted options for Central Texas include cedar elm, Mexican sycamore, bald cypress (near water), chinquapin oak (less susceptible than red oaks), Texas persimmon, and Mexican plum. Pick trees sized for the space so they won't need heavy pruning later.