First report of Neopestalotiopsis clavispora causing crown rot in strawberry in Italy

In October 2018, in Sele Valley (Italy), transplanted strawber-ry plants (Fragaria x ananassa) cv. Sabrina showed stuntedstarting growth. Then, a sample of 50 refrigerated plants, randomlycollected from the stock, was analysed. They wereexternally disinfected, cut lengthwise and brown roots andcrown reddish internal tissues fromsix plants were plated ontoPDA; after two week-incubation, white and cottony fungalcolonies, pale yellow on reverse side, developed, showingundulate margins and producing black acervuli, sometimesin yellow drops. Conidia were clavate (21.3 × 7.1 ?m, onaverage), composed by one pale yellow basal cell with twoappendages (13 ?m, on average), three central brown cellsand a yaline apical cell with one appendage (5.6 ?m, on average);the cells were separated by transverse septa. Based onthe morphology, the fungus was identified asNeopestalotiopsis sp. (Maharachchikumbura et al. 2014).Identification was performed by amplifying and sequencingof two genetic regions ITS (ITS1, ITS4) (White et al.1990) (GenBank accession No. MN149348) region and actingene fragments (Triact l, Triact 2) from two isolates. BLASTanalysis showed 100% identity with Neopestalotiopsisclavispora in NCBI GenBank.Each isolate was tested for pathogenicity on five strawberryplants by injecting five millilitres of a conidial suspension(1 × 106spores mL-1) in a wound on the crown and incubatedin growth chamber, at 25 °C and 85% humidity. After twomonths, reddish tissues were observed inside the collar, whichresembled those on the naturally diseased plants while nosymptoms were detected on water controls. The pathogenwas re-isolated satisfying Koch's postulate, demonstratingthat N. clavispora was responsible of reddish collar in strawberry as reported for the first time in Spain (Chamorro et al2016). To the best of our knowledge, this is the first report ofN. clavispora causing disease on strawberry in Italy.