Aerial Survey for Oak Wilt Incidence at Three Locations in Central Texas. D. N. Appel, Assistant Professor, Department of Plant Sciences, Texas A&M University, College Station 77843. R. C. Maggio, Assistant Professor, Department of Forest Science, Texas A&M University, College Station 77843. Plant Dis. 68:661-664. Accepted for publication 16 April 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-661.

Color-infrared aerial photography was used to survey oak mortality and identify oak wilt centers in central Texas. The highest incidence of oak wilt was found in the 38.850-ha Kerrville-Bandera site, where 1,007 mortality centers comprising 3,749.6 ha of dying or dead oaks were delineated. A random sample of these centers indicated 86% could be attributed to Ceratocystis fagacearum. In the 58,559-ha Austin site, 109 mortality centers were found. Of 16 randomly selected centers visited, six in the Austin site were caused by oak wilt. Oak wilt was not found in the 38.870-ha Fredericksburg-Johnson City site. Species affected by oak wilt in central Texas include Quercus virginiana, Q. fusiformis, Q. texana, Q. marilandica, Q. stellata, Q. sinuata var. breviloba, and Q. glaucoides. Bole sampling for isolation of C. fagacearum was consistently more successful than branch sampling. Veinal necrosis and tipburn were the symptoms most reliable for diagnosis of oak wilt on live oaks.