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Etiology

Acacia koa Seedling Wilt Caused by Fusarium oxysporum f. sp. koae, f. sp. nov.. Donald E. Gardner, Research scientist, Hawaii Field Research Center, Hawaii Volcanoes National Park 96718, Present address: Department of Botany, University of Hawaii, Honolulu 96822; Phytopathology 70:594-597. Accepted for publication 16 November 1979. 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, 1980. DOI: 10.1094/Phyto-70-594.

A wilt disease was observed among koa (Acacia koa) seedlings in Hawaii. Fusarium oxysporum was consistently isolated from root and stem tissue of these plants, as well as from wilted A. confusa and A. koaia seedlings. This fungus also may be responsible for, or contribute to, the premature decline and death of older koa trees established within Hawaii Volcanoes National Park. High wilt percentages among plants grown in a pathogen-free growth medium indicate that the fungus is seedborne. Seed disinfestation procedures did not reduce disease incidence. A new forma specialis, Fusarium oxysporum f. sp. koae, f. sp. nov., is proposed for this pathogen.