Occurrence and Relative Susceptibility of Apple Cultivars to Botryosphaeria Canker in Chile. B. A. Latorre, Adjunct Professor, Departamento de Ciencias Vegetales, Facultad de Agronomía, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile. M. V. Toledo, Former Student, Departamento de Ciencias Vegetales, Facultad de Agronomía, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile. Plant Dis. 68:36-39. Accepted for publication 18 July 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-36.

A canker disease initially observed on the trunks of Red King Oregon apple trees was shown to be caused by Botryosphaeria dothidea, a fungus not previously reported on apples in Chile. Trunk symptoms were characterized by the presence of flat, sunken cankers. Initially, the surface of the bark turned orange to pink, developed a papery appearance, and sloughed away. Abundant black pycnidia extruded through the outer layer of the bark. All B. dothidea isolates tested caused fruit rot on apple cultivars Granny Smith, Starking Delicious, and Richared Delicious and produced cankers after 8 wk on the trunks of artificially inoculated 1-yr-old Red King Oregon apple trees. Trunk susceptibility was dependent (P = 0.01) on cultivar, isolate, and inoculation position. Red King Oregon was the most susceptible cultivar, followed by Red Spur and Starkrimson. Granny Smith, Granny Smith Spur, and Golden Spur were the most resistant cultivars. Differences in virulence among fungal isolates were observed. At present, Botryosphaeria canker of apple is considered of minor importance but is a potential threat to the Chilean apple industry.