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First Report of Stem Blight Caused by Botrytis cinerea on Jasminum officinalis in Italy

Common jasmine (Jasminum officinalis L.) is an evergreen shrub that is native to the Middle and Far East. It is widely grown in Europe as an ornamental plant and in southeastern France for fragrance for the perfume industry. In March of 2008, a previously undescribed disease was observed on potted (6-month- to 3-year-old) common jasmine plants growing in open fields in a nursery of eastern Sicily, Italy. More than 20% of the plants showed disease symptoms. Diseased plants had small to large, brown or black lesions on stem. The lesions expanded rapidly, girdled the stem and caused blight of entire branches, and occasionally killed the plant. Abundant conidia and mycelia were detected on the surface of dead and dying stems under cool and humid conditions, which resulted in a moldy gray appearance. Botrytis cinerea Pers.:Fr. (1) was consistently isolated from affected tissues disinfected for 1 min in 1% NaOCl, rinsed in sterile water, and plated on potato dextrose agar (PDA). Colonies were at first white then became gray after 6 to 7 days when spores differentiated. White sclerotia developed after 8 to 9 days and turned black with age. Size of the conidia produced on 1-month-old culture ranged from 5.0 to 9.5 × 6.5 to 12.5 μm on the basis of 50 spore measurements. Sclerotia were spherical or irregular and ranged from 1.0 to 2.5 × 0.9 to 2.9 mm (average 1.7 × 1.8 mm). Stems of eight 6-month-old common jasmine plants were lightly wounded with a sterile razor and inoculated with 3-mm-diameter plugs of PDA from 10-day-old mycelial cultures, eight similar plants were inoculated with mycelium without wounding, and an equal number of noninoculated plants inoculated with only PDA plugs served as control. After inoculation, plants were enclosed in transparent plastic bags at 20 ± 2°C for 5 days. Stem lesions identical to the ones observed in the nursery were detected on all wounded and on two nonwounded fungus-inoculated plants within 5 to 7 days. Control plants remained healthy. B. cinerea was reisolated from typical lesions. The unusually cool and humid weather conditions recorded in Sicily are supposed to be highly conducive of disease outbreak. Although B. cinerea does not usually kill the plants, under these environmental conditions this disease can cause significant economic loss to ornamental nurseries. To our knowledge, this is the first report of B. cinerea causing stem blight on J. officinalis.

Reference: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CAB, Kew, Surrey, England, 1971.