Nematodes Associated with Dying Chamaecyparis nootkatensis in Southeastern Alaska. P. E. Hennon, USDA Forest Service, Juneau, AK 99801. G. B. Newcomb, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; C. G. Shaw III, USDA Forest Service, Juneau; and E. M. Hansen, Department of Botany and Plant Pathology, Oregon State University. Plant Dis. 70:352. Accepted for publication 9 December 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-352d.
Alaska-cedar (Chamaecyparis nootkatensis (D. Don) Spach) trees have been dying in large numbers throughout southeastern Alaska during the last 100 yr. To determine if nematodes are involved, soil with cedar fine roots was collected from beneath 27 declining and five healthy trees in six declining stands within a 4-km2 area. With use of a modified Baermann funnel technique, species of Pratylenchus, Aphelenchoides, Sphaeronema, and Crossonema were recovered. Pratylenchus was found in three samples from declining trees on one site, and Aphelenchoides was found in one sample. Except for a sample with 14 nematodes per gram of dry weight soil, the numbers of nematodes were low (six or fewer per gram of dry weight soil), regardless of tree health. However, Sphaeronema and Crossonema, previously unreported from southeastern Alaska, were found in 20 and 26 samples, respectively, from both healthy and declining trees. This frequency of recovery suggests that the role of these obligate parasites in cedar decline should be elucidated.