Occurrence of blue mold on tomato caused by Penicillium oxalicum in Korea

Abstract

A blue mold on tomato fruit caused by Penicillium oxalicum occurred sporadically in a greenhouse at Gyeongsangnam-do Agricultural Research and Extension Services. Infection usually occurred through wounds or cracks on the fruits. Symptoms began with water soaking lesions, then became watery and softened eventually. Colony of the causal fungus was white at the early growing stage, turned green on Czapek yeast extract agar and malt extract agar. Conidia were ellipsoidal in shape and 2-6×2-4μm in size. Stipes were septate, smooth, thin walled, and 90-280×3-4 μm in size. Penicilli were mostly biverticillate. Ramuli were 1-3 groups, smooth, and 10-16×2-3 μm in size. Rami were 1- 2 groups and 6-30×2-4 μm in size. Metulae were 2-3(5) verticils, smooth, and 12-20×3-4 μm in size. Phialides were 5-7 verticilate, ampulliform to cylindroidal, smooth, and 8-12×2-3 μm in size. Optimum temperature for growth was about 25°C. Pathogenicity of the fungus was proved on tomato fruit according to Koch s postulation. On the basis of mycological and pathological characteristics, the fungus was identified as P. oxalicum Currie & Thom. This is the first report of the blue mold on tomato fruit caused by P. oxalicum in Korea. © The Korean Society of Plant Pathology.