Koa wilt Koa wilt Koa wilt is a relatively new disease to Hawaii, discovered in 1980. Koa wilt is caused by a forma specialis of the fungus "Fusarium oxysporum", which is now abundant in Hawaiian soils and infects the native Acacia koa tree, a once-dominant species in the canopy of Hawaiian forests. Fusarium oxysporum f.sp. koae is believed to have been brought into Hawaii on an ornamental acacia plant. Fusarium fungi clog the tree xylem, causing significant wilt and mortality among these beautiful and iconic Hawaiian trees. The host for Koa wilt is Acacia koa, a tree that is native and endemic
Greater koa finch regeneration of koa forests, while introduced black rats ("Rattus rattus") preyed on young birds. Avian pox ("Poxvirus avium") and malaria ("Plasmodium relictum"), spread by mosquitoes, may have also been a factor. However, even before these issues became important, the koa finches were probably already living in marginal habitat due to the loss of lowland koa forests, as evidenced by the extinction of the other koa finch species (which lived on lower-elevation islands) prior to European contact. Greater koa finch The greater koa finch ("Rhodacanthis palmeri") was a species of finch in the Fringillidae family. It was found only in the