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Cryptodiaporthe melanocraspeda Canker as a Threat to Banksia coccinea on the South Coast of Western Australia. B L. Shearer, Science and Information Division, Department of Conservation and Land Management, 50 Hayman Rd., Como 6152, Western Australia . R. G. Fairman, and J. A. Bathgate, Science and Information Division, Department of Conservation and Land Management, 50 Hayman Rd., Como 6152, Western Australia. Plant Dis. 79:637-641. Accepted for publication 24 February 1995 . This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1995. DOI: 10.1094/PD-79-0637.

In 1989, large numbers of Banksia coccinea in the south coast region of Western Australia were observed dying downward from the apical branches. Plant death in 15-year-old B. coccinea increased from 40 to 98% in a 2.7-year period. Complete death of the stand within a relatively short time was typical of many diseased stands of B. coccinea in the region. Cryptodiaporthe melanocraspeda (anamorph Diplodina melanocraspeda) was the most frequently isolated fungus from lesions from individual plants at four sites. Of 109 isolations from pooled lesion samples at 53 sites, 47% were Botryosphaeria ribis, 36% C. melanocraspeda, 8% Mi-crosphaeropsis sp., 6% Cytospora sp., and 3% Zythiostroma sp. Pathogenicities of Botryos-phaeria ribis, C. melanocraspeda, and the Zythiostroma sp. were compared in wound-inoculated stems of Banksia baxteri and B. coccinea. Botryosphaeria ribis formed small lesions, which did not girdle stems, and was considered a weak pathogen. Although the Zythiostroma sp. formed lesions that girdled stems, it was not considered a major cause of death due to infrequent isolation from B. coccinea. It was concluded that C. melanocraspeda infection was associated with death of B. coccinea because the fungus formed lesions that girdled stems and because it was frequently isolated from dying B. coccinea throughout the banksia's geographic range. Within the region, C. melanocraspeda was isolated also from other Proteaceae: Banksia attenuata, B. baxteri, B. grandis, B. speciosa, Dryandra cuneata, and D. falcata. This report is the first record of a Zythiostroma sp. on Banksia and extends the geographic and host range of Cryptodiaporthe