Dispersal of Phytophthora cinnamomi Through Lateritic Soil by Laterally Flowing Subsurface Water. J. Kinal, Department of Conservation and Land Management, Dwellingup, Western Australia 6213. B. L. Shearer, and R. G. Fairman. Department of Conservation and Land Management, Como, Western Australia 6152; and Department of Conservation and Land Management, Dwellingup, Western Australia 6213. Plant Dis. 77:1085-1090. Accepted for publication 6 July 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-1085.

Phytophthora cinnamomi was recovered from water flowing at the base of a lateritic soil about 1 m deep and overlying concreted duricrust on a hillslope supporting a severely diseased forest of Eucalyptus marginata (jarrah) in south-western Australia. The water was collected by 20-m-long throughflow interception trenches dug down to the duricrust. The fungus also was recovered at depths greater than 2 m from piezometers drawing water perched on clay beneath the duricrust. Most inoculum-bearing water was collected in winter and early spring when deeper soil was warmer than near-surface soil. Collections also were made in autumn and summer following unseasonably heavy rainfall. Subsurface water flowed through the soil at least 120 m down the hillslope following a moderately intense winter rain event. Propagule density averaged 60 propagules per liter on selected days in spring. At least half of the propagules were identified as zoospores.