In February of 2008, wilt and collapse of sweet basil (Ocimum basilicum L.) was observed on approximately 20% of the plants in a commercial greenhouse in Demre, Antalya, Turkey. Crown and stems of infected plants were necrotic; leaves turned brown and wilted. Profuse, white mycelia and occasionally black sclerotia were found inside and outside of affected stems. Sclerotinia sclerotiorum (Lib). de Bary, identified based on morphological characteristics was isolated from sclerotia and symptomatic stems on potato dextrose agar amended with tetracycline. To conduct pathogenicity tests, sclerotia produced on carrot discs were surface disinfested in 70% ethanol and dried on sterilized filter papers. Ten sclerotia were placed in 9-cm-diameter glass petri plates containing 15 ml of sterilized distilled water. Plates were wrapped with Parafilm and incubated at 4°C for 5 to 6 weeks in the dark. Plates were then incubated at 15°C in 12 h of dark and 12 h of light. Apothecia developed after 2 weeks. Ascospores were harvested from apothecia with distilled water by crushing and shaking the apothecia in centrifuge tubes. Thirty basil plants sprayed with ascospores (106 spores per ml) were maintained in a growth chamber at 22°C and 90% humidity. After 2 weeks, necrotic leaves and stems were observed on all inoculated plants. S. sclerotiorum was recovered from symptomatic tissues. No symptoms developed on the 30 basil plants sprayed with sterile distilled water. The pathogenicity test was repeated with similar results. S. sclerotiorum on basil has been reported in Canada (4), the United States, (2,3), and Italy (1). To our knowledge, this is the first report of S. sclerotiorum on basil in Turkey.
References: (1) A. Garibaldi et al. Plant Dis. 81:124, 1997. (2) G. E. Holcomb and M. J. Reed. Plant Dis. 78:924, 1994. (3) S. T. Koike. Plant Dis. 84:1342, 2000. (4) T. C. Paulitz. Plant Dis. 81:229, 1997.
