The mulberry tree(Morus sp.)is a perennial crop has been grown to rear silkworms worldwide for over four thousand years,but recently there has been increasing demands for the fruits which contain various beneficial substances for human health,and effective for the treatment of sore throat,fever,hypertension and anemia(Ju et al.2016).In 2016,an incomplete statistics indicated that the growing area of the tree has been remarkably increasing,reached to 53,300 hm2,and the yield was about to 80 ton in China.In April 2017,mulberry fruits with light to dark brown,soft,watery symptoms were observed with 5%~20%incidence in cultivation fields in Wuhan,China.Fruits with disease symptoms were collected,surface-disinfested in 75%ethanol solution for 1 min,4%NaOCl solution for 2 min,rinsed thrice in sterilized distilled water,air dried,plated on potato dextrose agar(PDA),and incubated at 25℃ in the dark.Mycelia of the isolates were initially hyaline and white,becoming dark gray after culturing.The conidia produced on PDA were aseptate,ellipsoid or ovoid,3.0 to 11.8 × 2.2 to 6.8 μm.Microsclerotia were round,spherical,or irregular in shape,1.0 to 5.8 × 1.0 to 4.0 mm.These morphological characteristics were consistent with those of Botrytis cinerea,anamorph of Botryotinia fuckeliana(Zhang 2006).Bg2 was selected as a representative strain for molecular identification and pathogenicity tests.The internal transcribed space(ITS)region was amplified with primers ITS1/ITS4 and sequenced.BLAST analysis of the 521-bp segment(GenBank accession nos.MF445059)showed 99%identity with the sequence of B.cinerea.For pathogenicity tests,three healthy fruits from the field were surface-disinfested in 75%ethanol solution for 30 s,rinsed thrice in sterilized distilled water,placed on sterile moist paper towels in a 9 cm plate,and inoculated by injection of 100 μl conidia suspension(1 × 105 conidia/ml).Three healthy fruits were inoculated with injection of 100 μl of sterile distilled water as controls.The plates were covered individually with plastic film for 5 days after inoculation to maintain high relative humidity and were placed in an incubator at 25℃.Symptoms similar to those observed in the field developed on fruits after 3 days inoculation,and after 5 days,all fruits were severely infected; control plants remained healthy.Pathogenicity tests were repeated three times,and the same pathogen was consistently reisolated from the symptomatic tissues.To our knowledge,this is the first report of B.cinerea causing fruit rot on mulberry in China.