Root Rot of Brachychiton populneus Seedlings Caused by Lasiodiplodia theobromae. C. M. Sandlin, Graduate Research Assistant, Department of Plant Pathology, University of California, Riverside 92521. D. M. Ferrin, Assistant Professor, Department of Plant Pathology, University of California, Riverside 92521. Plant Dis. 76:883-885. Accepted for publication 24 February 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0883.

Lasiodiplodia theobromae was the causal agent in the death of several hundred 18-mo-old Australian bottle trees (Brachychiton populneus) at a nursery in southern California. Disease became apparent after the plants, which had been shipped bare root from Israel, were repotted in California. The fungus infects the taproot, causing maceration and collapse of tissue and the eventual wilting and death of the plant. Inoculation of 1-cm-deep wounds with 10 µl of spore suspension (1 × 10⁵ pycnidiospores per milliliter) consistently resulted in infection when wounds were wrapped in Parafilm after inoculation. Partial control of the disease was achieved by dipping bare roots in a benomyl suspension for 5 min before inoculation.