Tree Susceptibility, Inoculum Availability, and Potential Vectors in a Texas Oak Wilt Center

Abstract

Three factors important to the spread of Ceratocystis fagacearum, the oak wilt pathogen, were studied in central Texas during 1983-1985. These factors were: 1) the formation of fungal mats on diseased Spanish oaks (Quercus texana), 2) the activities of nitidulid beetles, and 3) the seasonal susceptibility of live oak (Q. fusiformis) to infection by the pathogen. Fungal mats formed on 73% and 3 1% of the trees observed in March of 1984 and 1985, respectively. Peaks of nitidulid activity were observed during February - May of each year. Inoculations were most successful when made in roots or main stems during March or late May. These observations indicate that inoculations by contaminated nitidulids are most likely to occur in spring. Wounding should be avoided then to minimize insect transmission of the fungus.