Oak wilt pruning calendar for San Antonio.
Do not prune oak trees in San Antonio between February 1 and June 30. That is the high-risk oak wilt window, when the sap-feeding beetles that carry the fungus are most active and fresh cuts draw them in. July through January is safe, and December and January are ideal. Paint every cut on an oak immediately, in every month of the year. Storm damage is the only exception: a broken oak limb should be cut clean and painted right away whatever the date, because the wound is already open.
Published 2026-08-29 · Last reviewed 2026-08-29 · Guidance follows the Texas A&M Forest Service and the Texas Oak Wilt Partnership.
Month by month
| Month | Oak wilt risk | What to do |
|---|---|---|
| January | Ideal | Best month of the year. Beetles are least active in the cold and the tree is dormant. Do planned oak pruning now. |
| February | High risk - do not prune | High-risk window opens. Do not prune oaks except for genuine hazards. |
| March | High risk - do not prune | Peak beetle activity and peak fungal mat production. No oak pruning. |
| April | High risk - do not prune | Still peak risk. No oak pruning. |
| May | High risk - do not prune | Still high risk. No oak pruning. |
| June | High risk - do not prune | Last month of the high-risk window. Wait until July. |
| July | Safe | Window reopens. Summer heat suppresses beetle activity and fungal mats. Safe to prune. |
| August | Safe | Safe. The hottest part of the year is one of the two low-risk periods. |
| September | Safe | Safe. Good month to schedule work ahead of the fall rush. |
| October | Safe | Safe. Cooling temperatures, low beetle pressure. |
| November | Ideal | Excellent. Dormant season begins and risk is at its lowest. |
| December | Ideal | Excellent. Coldest, lowest-risk period alongside January. |
The calendar above reduces risk. It does not remove it. Any wound on an oak - a pruning cut, a storm break, a mower strike on a surface root, construction damage - should be painted within minutes, not hours, in any month. Pruning paint or plain latex paint both work. This is the cheapest thing a homeowner can do to protect a live oak, and it is the step most often skipped.
Key facts at a glance
- High-risk pruning window
- February 1 - June 30
- Safe pruning window
- July 1 - January 31
- Ideal months
- December and January
- Wound paint
- Advised year-round, immediately after any cut
- Fastest-dying species
- Red oaks (Spanish, Shumard, blackjack) - weeks
- Root-graft spread
- Live oaks, through fused root systems
- Trench depth to break root spread
- 4-5 feet
Why the window exists
Oak wilt is a fungal disease. On infected red oaks - Spanish oak, Shumard, blackjack - the fungus forms spore mats under the bark. Sap-feeding beetles feed on those mats, pick up spores, and then fly to the freshest sap they can find, which is an open pruning cut on a healthy oak. Beetle activity and mat production both peak in spring, which is what defines the February-through-June window.
The second route has nothing to do with the calendar. Live oaks growing near one another fuse their roots underground, and the fungus moves tree to tree through those connections. That is why oak wilt in a live oak motte spreads as a widening circle, and why stopping it means trenching four to five feet deep to sever the shared roots between a sick tree and its healthy neighbors.
There is no cure for an infected tree. High-value live oaks can be treated preventively with propiconazole injected by a trained applicator, and dead red oaks should be removed promptly so they cannot form new spore mats. Anyone promising to cure an infected oak is selling something.
Questions
Do not prune oaks in San Antonio from February 1 through June 30. That is the high-risk oak wilt window: the sap-feeding beetles that carry the oak wilt fungus are most active, fungal mats on infected red oaks are producing spores, and a fresh cut is an open invitation. The Texas A&M Forest Service recommends avoiding oak pruning during these months.
December and January are the safest months. Beetle activity is lowest in the cold and the tree is dormant, so a wound is least likely to attract a spore-carrying beetle. July through November is also considered safe, with the peak summer heat suppressing beetle activity.
Yes, for genuine hazards. A limb broken by a storm, a branch on a roof, or a tree threatening a structure should be cut clean and the wound painted immediately, whatever the month. The wound is already open in that case, so waiting increases risk rather than reducing it. Elective pruning - shaping, clearance, thinning - waits until July.
Yes, every time, in every month. Texas A&M Forest Service guidance is to paint all wounds on oaks - pruning cuts, storm breaks, and accidental damage from mowers or construction - immediately, within minutes rather than hours. Any commercial pruning paint or latex paint works. Painting is advised year-round, not only during the high-risk window.
Two ways. Above ground, sap-feeding (nitidulid) beetles pick up spores from fungal mats that form under the bark of infected red oaks and carry them to fresh wounds on healthy oaks. Below ground, live oaks growing near each other fuse their roots, and the fungus moves tree to tree through those connections - which is why oak wilt in a live oak motte spreads outward in a widening circle.
No. There is no cure for an infected tree. Spread can be slowed: trenching four to five feet deep severs the shared roots between a sick tree and healthy ones, high-value live oaks can be treated preventively with propiconazole injected by a trained applicator, and dead red oaks are removed promptly so they cannot form spore mats. Red oaks typically die within weeks of showing symptoms; live oaks decline over months to years.
“Oak Wilt Pruning Calendar for San Antonio,” San Antonio Tree Removal, last reviewed 2026-08-29. https://sanantoniotree.services/oak-wilt-calendar/
Underlying guidance: Texas A&M Forest Service - Prevent the Spread of Oak Wilt in Texas and the Texas Oak Wilt Partnership.
If an oak on your property is thinning, dropping leaves out of season, or showing veins that have gone yellow then brown, an on-site look will tell you whether it is oak wilt, drought stress, or something else. The assessment is free and the answer is honest - including when the answer is that the tree cannot be saved.