Post Oak Decline (Multiple agents) - This rapid decline of post oaks is the result of varying extremes (drought and drowning) that make the trees susceptible to attack by the cankers, root rots, soil moisture, and wood-boring insects described above. All of these problems were made worse by the historic drought in Texas in 2011 that crippled tree health to such an extent that trees are still suffering today. Extreme drought induces stress so that the trees must cope by expending storage carbohydrates (starches) to compensate for the strain.