Prune during the coldest months of winter or the hottest days of summer when the risk of oak wilt infection is low.
The best time to prune your oaks is in the winter months of November through January when the beetles are least active.
The next best time to prune is in the heat of summer when temperatures rise above 100 degrees; the beetles are less active and oak wilt fungalmats dry up in extreme heat.
Use pruning paint even during the low risk periods. "Low risk" doesn't mean "no risk."
Never prune February through June
Springtime is the highest risk season for new oak wilt infections. February through June is the period when the three risk factors come together to create perfect conditions for new oak wilt outbreaks:
Fungal mats proliferate in the moderate temperatures and high humidity.
Sap feeding beetles are active and abundant.
Oaks are more susceptible to infection in springtime when the sap is rising.