Pathogenicity, Symptom Development, and Colonization of by .

Extensive mortality of (ōhia) trees has been associated with spp. on Hawaii Island and was named rapid ōhia death (ROD). Both and have been associated with ROD, although appears to be the more important pathogen. Crown observations and dissections of forest trees either wound-inoculated with, or naturally infected by, were conducted to confirm pathogenicity and document patterns of host colonization. In pathogenicity trials, one of three and two of three trees inoculated with the fungus in February and August, respectively, exhibited crown wilt symptoms at 92 and 69 days after inoculation. Extensive, radial, black staining of the sapwood was found in main stems, while no crown wilt or xylem staining was found in control trees. Xylem staining, necrotic phloem, and fungus presence was noted in six trees inoculated in May to June and harvested 37 to 42 days later, and these observations were compared with those in two naturally infected trees felled in early August. Contiguous xylem staining was found in the main stems and into crowns of all diseased trees, while discontinuous streaks of xylem staining extended into the main forks and side branches. Necrotic phloem associated with xylem staining occurred on the lower stems of inoculated trees. Aside from the necrotic phloem and radial staining of the sapwood, symptom development in ōhia infected with is similar to other systemic wilt diseases on hardwood trees. We propose Ceratocystis wilt of ōhi`a as the official name of the disease.