Sala (Salacca edulis, a hybrid between S. wallichiana and S. glabrescens) is extensively cultivated in Southeast Asia for its highly valued fruit (1). During the rainy season in 1999, a fruit rot of sala caused by Thielaviopsis paradoxa (2) was observed to occur on immature and mature fruits for the first time in Trad and Chantaburi provinces, Thailand. Infected fruit discolored brown to black and appeared rotted with white mycelia on the lesions. Fruit eventually abscised. Conidiophores of the fungus were usually straight and hyaline to pale brown. The conidia (8.75 to 12.5 × 3.75 to 5.5 μm) were cylindrical to elliptical and also hyaline to pale brown. The brown, smooth, and ovate chlamydospores (15 to 25 × 8.7 to 14.5 μm) were borne terminally in chains from short hyphal branches. To fulfill Koch's postulates, six isolates of the fungus were grown on potato-dextrose agar for 7 days. Plugs of mycelia agar (0.5 cm in diameter) from each isolate were inoculated onto fresh fruit (four fruit per isolate) after the surface was disinfected with 10% sodium hypochlorite for 3 min. Non-inoculated fruits with sterile distilled water were served as controls. After incubation at 30°C and 80% RH in a humidity chamber for 4 days, lesions occurred on all the inoculated fruit. The fungus was subsequently recovered from the lesions. One isolate has been deposited in the Fungal Culture Collection, King Mongkut's Institute of Technology, Ladkrabang, Thailand (TF 1-6/1999).
References: (1) G. Hamballi et al. 1989. Proceedings of the First PROSEA International Symposia, Indonesia. (2) A. Johnston and C. Booth. 1983. Plant Pathologist's Pocketbook. CMI, Surrey, England.