How to Identify and Manage Oak Wilt in Texas
Oak wilt, one of the most destructive tree diseases in the United States, is killing oak trees in central Texas at epidemic proportions. Oak wilt is an infectious disease caused by the fungus Ceratocystis fagacearum, which invades and disables the water-conducting system in susceptible trees. All oaks (Quercus spp.) are susceptible to oak wilt to some degree, but some species are affected more than others. The successful management of oak wilt depends on correct diagnosis and an understanding of how the pathogen spreads between different oak species.
Red oaks, particularly Texas (aka Spanish) oak (Q. buckleyi), Shumard oak (Q. shumardii), blackjack oak (Q. marilandica), and water oak (Q. nigra) are extremely susceptible and may play a unique role in the establishment of new oak wilt infections.
White oaks include post oak (Q. stellata), bur oak (Q. macrocarpa), Mexican white oak (Q. polymorpha), white shin oak (Q. sinuata var. breviloba), Durand oak (Q. sinuata), Lacey oak (Q. laceyi), and chinkapin oak (Q. muehlenbergii). Although white oaks show some tolerance of the disease, all oaks are susceptible to the fungus.
Live oaks (Q. virginiana and Q. fusiformis) are intermediate in susceptibility to oak wilt, but are most seriously affected due to their tendency to grow from root sprouts and form vast interconnected root systems that allow movement (or spread) of the fungus between adjacent trees.